WO2021244512A1 - Application of diantimony trioxide material as semiconductor integrated circuit inter-layer or inter-metal dielectric material - Google Patents

Abstract

New use of using diantimony trioxide as a semiconductor integrated circuit inter-layer or inter-metal dielectric material in the technical field of nano materials, the field of microelectronics, and the field of integrated circuit manufacturing. A diantimony trioxide material is a molecular crystal, which is of a two-dimensional or three-dimensional structure formed by self-assembly of Sb4O6 cage-like molecules by means of van der Waals' force. The material is α-phase diantimony trioxide, having (1) a low dielectric constant k: 1.8-2.5; (2) a wide energy bandgap Eg: 5.5-5.7 eV; (3) resistance to high temperature of 550°C under normal pressure; (4) ultrahigh electric breakdown field strength EB: 1.4-2.5 MV/cm; and (5) Young's modulus E: 14.4-16 GPa, and mechanical strength: 0.93-1.32 GPa. Diantimony trioxide is a novel low dielectric constant material that has not been discovered and has not been developed, can be used for the semiconductor integrated circuit inter-layer or inter-metal dielectric material, and has great commercial potential and value.

Description

Application of antimony trioxide material as a dielectric material between semiconductor integrated circuit layers or between metals Technical field

The invention relates to the technical field of nanomaterials, microelectronics and integrated circuit manufacturing, in particular to the use of low dielectric constant of antimony trioxide as a new application of dielectric material between semiconductor integrated circuit layers or between metals.

Background technique

The technical development direction of integrated circuit (IC) is to improve the performance of microprocessors. The main method is to reduce the device size with a more precise process method to achieve a greater device density; when a single chip has a higher density The calculation speed and efficiency of the microprocessor can be effectively improved with the number of devices. The above is the development trend of integrated circuit manufacturing technology inferred by Moore’s Law. As shown in Figure 1, the field alliance (current name: International Roadmap for Devices and Systems, referred to as IRDS) formed by IBM, Intel, other industry peers, and academic peers is the technology node jointly identified as the gate of field-effect transistors. It is determined by the size of the channel (Gate Channel). When the gate channel is reduced, it means that the size of the device is reduced. For example, for the current 10nm (10nm) technology node, the dielectric constant (k) value of the dielectric material required for the metal circuit layer Must be as low as k=2.4. At present, the physical properties of low dielectric constant (<2.4) materials in the industry have reached their own limits; in the face of smaller technology nodes in the future, there is a lack of a stable ultra-low constant (<2.0) dielectric material.

As shown in Figure 2, in a typical microprocessor, the metal circuit wiring layer for device interconnection requires low-dielectric materials to separate the layers and between layers. The traditional low-dielectric material is silicon dioxide (SiO ₂ , k=3.8～4.1). As the device density of integrated circuits continues to increase, wiring size and spacing continue to decrease, resulting in a serious problem, that is, when the signal propagation delay gradually increases, the power consumption caused by crosstalk noise and resistance-capacitance coupling is due to wiring capacitance (including layer The inter- _{line capacitance C LG} and the inter-line capacitance C _LL ) increase accordingly; when the inter-line connection distance is less than 0.3 μm, C _LG is already very small compared with the total capacitance; when the inter-line connection distance is less than 0.25 μm, C _LL becomes the main part of the total capacitance in the IC. In addition, a smaller wire size will increase the resistivity of the metal wire, and a narrower wire pitch will increase C _LL . Therefore, as the size of the gate channel decreases, the interconnection delay (Interconnection Delay, commonly known as RC delay) becomes the main part of the total delay in the IC, which limits the improvement of the device performance.

To cope with the large technical nodes in the past, traditional low-dielectric constant (k<3.9) materials and conductive metals (mainly aluminum, Al) are sufficient. The current 10nm and 7nm technology nodes have become the mainstream, and lower dielectric constant (k<2.4) materials and higher conductive metals (such as Cu) need to be used to meet the requirements of future equipment, improve IC operating speed, and reduce power consumption and crosstalk. A number of semiconductor manufacturers have proven that replacing Al wires with Cu wires can reduce the interconnect delay by about 35%. This is because the resistivity of pure copper is only 60% of that of aluminum, and replacing the traditional Al wiring with Cu means that the interconnection delay is reduced from the perspective of resistance. On the other hand, because capacitance is mainly determined by the dielectric constant k of the insulator, a decrease in k will result in lower capacitance and interconnection delay. If air (k=1) is used instead of SiO ₂ (k=3.9), the interconnection delay will be further reduced by about 75%.

At present, the research work of low dielectric constant materials mainly focuses on silicon-based materials and organic polymer materials. After years of development, silicon-based low-permittivity materials are slowly approaching their limits, while low-permittivity materials of organic polymers have poor compatibility with existing semiconductor processes, coupled with their own low thermal stability and mechanical properties. Stability, its development has been restricted. The dielectric material of the IC device occupies 40-60% of the entire chip volume. It needs to have zero leakage current, low dielectric constant, low cost, high thermal stability (need to be able to withstand the high temperature semiconductor process temperature of at least 400℃), and have physical and chemical properties. Compatibility related to reaction and semiconductor process, good mechanical properties and other properties. Therefore, the development of new non-silicon-based low-dielectric constant materials is of great significance.

Summary of the invention

In view of the above-mentioned problems of the existing integrated circuit technology, the purpose of the present invention is to use the antimony trioxide molecular crystal material as the application of the interlayer or intermetal dielectric material of the semiconductor integrated circuit. Compared with the prior art, the present invention It is a new, more stable, and lower dielectric constant dielectric material. For the future development of sub-10 nanometer products, the function of the antimony trioxide material of the present invention will meet the shortcomings of related technology development.

One aspect of the present invention provides a semiconductor integrated circuit. The interlayer or intermetal dielectric material of the semiconductor integrated circuit includes antimony trioxide. The antimony trioxide material is a molecular crystal and is made of Sb ₄ O ₆ cage-like molecules. A two-dimensional or three-dimensional structure formed by van der Waals force connection.

In some embodiments of the present invention, the interlayer or intermetal dielectric material of the semiconductor integrated circuit further includes a composite structure of antimony trioxide material and air voids.

In some embodiments of the present invention, the antimony trioxide material is α-phase antimony trioxide.

In some embodiments of the present invention, the antimony trioxide material is a molecular crystal formed by self-assembly of _{Sb 4} O _{6 cage-like molecules.}

In some embodiments of the present invention, the antimony trioxide material is a cubic crystal system, belonging to space group No. 227, and the symbol is expressed as

晶面间距为

In some embodiments of the present invention, the antimony trioxide material has

Interplanar spacing is

In some embodiments of the present invention, the single crystal morphology of the antimony trioxide material is triangular nanosheets.

In some embodiments of the present invention, the single crystal morphology of the antimony trioxide material is octahedral crystal grains.

In some embodiments of the present invention, the dielectric constant of the antimony trioxide material is between 1.8 and 2.5.

In some embodiments of the present invention, the optical band gap of the antimony trioxide material is between 5.5 and 5.7 eV.

In some embodiments of the present invention, the breakdown field strength of the antimony trioxide material is between 1.4 and 2.5 MV/cm.

In some embodiments of the present invention, the antimony trioxide material can withstand a temperature greater than or equal to 550°C under normal pressure.

In some embodiments of the present invention, the Young's modulus of the antimony trioxide material is between 14.4 and 16 GPa; the mechanical strength of the antimony trioxide material is between 0.93 and 1.32 GPa.

In some implementation methods of the present invention, the theoretical value of the dielectric constant of the single crystal structure of the antimony trioxide is 2.24.

In some embodiments of the present invention, the thickness of the triangular nanosheets is 0.6 nm to 2000 nm.

In some embodiments of the present invention, the grain size of the octahedral crystal grains is 0.2 μm-10 μm.

Another aspect of the present invention provides an application of using antimony trioxide material as a dielectric material between semiconductor integrated circuit layers or between metals. The antimony trioxide material is a molecular crystal made of Sb ₄ O ₆ cages. A two-dimensional or three-dimensional structure formed by connecting like molecules through van der Waals forces.

In some embodiments of the present invention, the antimony trioxide material is α-phase antimony trioxide.

In some embodiments of the present invention, the antimony trioxide material is a molecular crystal formed by self-assembly of _{Sb 4} O _{6 cage-like molecules.}

In some embodiments of the present invention, the antimony trioxide material is a cubic crystal system, belonging to space group No. 227, and the symbol is expressed as

晶面间距为

In some embodiments of the present invention, the antimony trioxide material has

Interplanar spacing is

In some embodiments of the present invention, the single crystal morphology of the antimony trioxide material is triangular nanosheets.

In some embodiments of the present invention, the single crystal morphology of the antimony trioxide material is octahedral crystal grains.

In some embodiments of the present invention, the thickness of the triangular nanosheets is 0.6 nm to 2000 nm.

In some embodiments of the present invention, the particle size of the octahedral crystal grains is 0.2 μm-10 μm.

In some embodiments of the present invention, the optical band gap of the antimony trioxide is between 5.5 and 5.7 eV; the dielectric constant is between 1.8 and 2.5; and the breakdown field strength is between 1.4 and 2.5 MV/cm ; The tolerable temperature is greater than or equal to 550°C; the Young's modulus is between 14.4～16GPa; the mechanical strength is up to 0.93～1.32GPa.

In some implementation methods of the present invention, the theoretical value of the dielectric constant of the single crystal structure of the antimony trioxide is 2.24.

In some embodiments of the present invention, the preparation method of the antimony trioxide material includes: under vacuum conditions and an inert gas and/or oxygen atmosphere, the antimony trioxide powder and/or the metal antimony powder are heated and volatilized, and after the reaction Deposition on the substrate to obtain antimony trioxide.

In some embodiments of the present invention, the substrate is selected from a combination of one or more of mica, silicon dioxide, graphene, and sapphire, preferably a mica substrate.

In some embodiments of the present invention, the vacuum condition for the synthesis of the material, that is, the pressure in the reaction is 3 to 500 Torr.

In some embodiments of the present invention, the inert gas is argon and/or nitrogen, preferably argon.

In some embodiments of the present invention, the synthesis reaction temperature is 320-700°C.

Another aspect the present invention provides antimony trioxide and air voids in the application of the composite structure between the metal layers or the semiconductor integrated circuit, the molecular crystal material is antimony trioxide, Sb ₄ O ₆ is a cage-like molecules by van der Waals A two-dimensional or three-dimensional structure formed by force connection.

In some embodiments of the present invention, the antimony trioxide material is α-phase antimony trioxide.

In some embodiments of the present invention, the antimony trioxide material is a molecular crystal formed by self-assembly of _{Sb 4} O _{6 cage-like molecules.}

In some embodiments of the present invention, the antimony trioxide material is a cubic crystal system, belonging to space group No. 227, and the symbol is expressed as

晶面间距为

In some embodiments of the present invention, the antimony trioxide material has

Interplanar spacing is

In some embodiments of the present invention, the single crystal morphology of the antimony trioxide material is triangular nanosheets.

In some embodiments of the present invention, the single crystal morphology of the antimony trioxide material is octahedral crystal grains.

In some embodiments of the present invention, the dielectric constant of the antimony trioxide material is between 1.8 and 2.5.

In some embodiments of the present invention, the optical band gap of the antimony trioxide material is between 5.5 and 5.7 eV.

In some embodiments of the present invention, the breakdown field strength of the antimony trioxide material is between 1.4 and 2.5 MV/cm.

In some embodiments of the present invention, the antimony trioxide material can withstand a temperature greater than or equal to 550°C under normal pressure.

In some embodiments of the present invention, the Young's modulus of the antimony trioxide material is between 14.4 and 16 GPa; the mechanical strength of the antimony trioxide material is between 0.93 and 1.32 GPa.

In some implementation methods of the present invention, the theoretical value of the dielectric constant of the single crystal structure of the antimony trioxide is 2.24.

In some embodiments of the present invention, the thickness of the triangular nanosheets is 0.6 nm to 2000 nm.

In some embodiments of the present invention, the particle size of the octahedral crystal grains is 0.2 μm-10 μm.

In some embodiments of the present invention, the morphology of the composite structure of the antimony trioxide material and the air voids is a thin film composed of the stacking of triangular nanosheets, wherein the thin film includes stacked triangular nanosheets that cause natural Air voids created.

In some embodiments of the present invention, the volume ratio of the antimony trioxide material and the air gap in the composite structure of the antimony trioxide material and the air gap is 5:1 to 100:1.

Another aspect of the present invention provides a composite structure of antimony trioxide material and air voids. The morphology of the composite structure of antimony trioxide material and air voids is a thin film structure formed by stacking octahedral crystal grains, wherein The film includes naturally occurring air voids caused by stacking octahedral crystal grains.

In some embodiments of the present invention, the volume ratio of the antimony trioxide material and the air gap in the composite structure of the antimony trioxide material and the air gap is 5:1 to 100:1.

Compared with the prior art, the beneficial effects of the present invention are: the present invention discloses a type of ultra-low dielectric constant, high temperature thermal stability and electrical breakdown resistance, wide energy band gap, high Young's modulus / high The mechanically strong antimony trioxide material can be used as a dielectric material between the layers of semiconductor integrated circuits or between metals, reducing the interconnection delay constraints in ICs, and improving the performance of integrated circuits. It has great commercial potential and value.

Description of the drawings

Figure 1 shows the requirements for the k value of low k materials for different IC technology nodes determined in the prior art.

Figure 2 is a cross-section of a chip at a 32nm technology node developed by IBM in the prior art, in which interconnecting copper wires are separated by low-dielectric constant materials, and layers are also separated by low-dielectric constant materials.

Figure 3 _{shows the adamantane C 10} H ₁₆ molecular structure and the adamantane-like cage-like Sb ₄ O ₆ cage-like molecular structure.

FIG. 4 is a schematic cross-sectional view of a logic device in an integrated circuit, which is a further reduced view of FIG. 2. The figure indicates the application scenarios of the material of the present invention: low dielectric constant material 1 and low dielectric constant material 2.

Fig. 5 is a schematic diagram of an apparatus _{for preparing Sb 2} O _{3 nanosheets or films in Examples 1 to 6.} Among them, the synthesis cavity is a quartz tube with a diameter of 1 inch and a length of 1 meter, and the raw materials and substrates placed in the quartz tube are indicated in the figure.

Fig. 6 is a schematic diagram of the structure of the _{α-phase Sb 2} O ₃ (111) plane prepared in Examples 1 to 6; showing the arrangement rules of the _{Sb 4} O _{6 cage-like molecules.}

FIG. 7 is an optical microscope image of the α-phase Sb ₂ O _{3 nanosheets synthesized in Example 1. FIG.}

FIG. 8 is an optical microscope image of the α-phase Sb ₂ O _{3 nanosheets synthesized in Example 2. FIG.}

9 is a scanning electron microscope image of α-phase Sb ₂ O _{3 octahedral particles synthesized in Example 3.}

10 is a scanning electron microscope image of α-phase Sb ₂ O _{3 octahedral particles synthesized in Example 4.}

FIG. 11 is a height measurement diagram of an atomic force microscope of the sample prepared in Example 1, showing nanosheets with different thicknesses.

12 is a high-resolution X-ray photoelectron spectrum of the α-phase Sb ₂ O ₃ nanosheets synthesized in Example 1, showing ultra-high purity α-phase Sb ₂ O ₃ .

13 is a transmission electron microscope image (left) of the α-phase Sb ₂ O ₃ nanosheets synthesized in Example 1 and scanning images of Sb element (middle) and O element (right) measured by X-ray energy spectrum analysis.

晶面间距为

图中各个亮点匹配对应的Sb ₄O ₆笼状分子如图标示。 14 is a high-resolution transmission electron microscope image of the α-phase Sb ₂ O _{3 nanosheets synthesized in Example 1.} Labeled as Sb ₂ O ₃

Interplanar spacing is

_{The corresponding Sb 4} O ₆ cage-shaped molecules corresponding to the bright spots in the figure are marked as shown in the figure.

FIG. 15 is a diffraction lattice image taken by a transmission electron microscope of the α-phase Sb ₂ O ₃ nanosheets synthesized in Example 1, and 4 different diffraction points are marked, representing the four crystal planes respectively.

16 is an X-ray diffraction pattern of the α-phase Sb ₂ O _{3 nanosheets synthesized in Example 1.} Refer to the PDF chart, the α-phase Sb ₂ O ₃ nanosheets have fewer diffraction peaks, which is a phenomenon caused by the two-dimensional structure.

Figure 17 is the X-ray diffraction pattern of the α-phase Sb ₂ O ₃ octahedral particles synthesized in Example 5, in which the PDF chart is a reference for interpretation. The diffraction peaks of α-phase Sb ₂ O ₃ particles can be one-to-one corresponding to the PDF pattern.

18 is an optical microscope image of a continuous thin film of α-phase Sb ₂ O _{3 and air voids synthesized in Example 5. FIG.}

19 is an optical microscope image of a continuous thin film of α-phase Sb ₂ O _{3 and air voids synthesized in Example 6. FIG.}

20 is a schematic cross-sectional view of a continuous film of _{α-phase Sb 2} O ₃ and air voids synthesized from Example 5 and Example 6. FIG. The black line segments represent the sides of the nanosheets, and there are air gaps between the nanosheets, and the two form a "composite structure of antimony trioxide and air gaps."

21 is the absorption spectrum analysis of α-phase Sb ₂ O _{3 nanosheets synthesized in Example 1.} The figure shows the Tauc curve characterization of the optical band gap of α-phase Sb ₂ O ₃ nanosheets, and the result shows that the optical band gap is 5.6 eV.

22 is a morphology of the α-phase Sb ₂ O ₃ nanosheets synthesized in Example 1 before and after high-temperature treatment, in which the upper row is an optical microscope image, and the lower row is a scanning electron microscope image.

Figure 23 is a Raman spectrum of the α-phase Sb ₂ O ₃ nanosheets synthesized in Example 1 after different high-temperature treatments. It can be seen that the α-phase Sb ₂ O ₃ nanosheets can be stabilized to 550°C.

Figure 24 is a scanning microwave impedance microscope characterization diagram of the α-phase Sb ₂ O ₃ nanosheets synthesized in Example 1, where (a) is an atomic force microscope height diagram, (b) is a scanning microwave impedance-reactance signal diagram, and (c) is Scan the microwave impedance-resistance signal graph.

Figure 25 shows the data of the _{synthesis and α-phase Sb 2} O ₃ nanosheets of Example 1 characterized by scanning microwave impedance microscope. Among them, the nano-sheets are on the mica substrate; the different curves are the physical matching of the electric field obtained by the finite element simulation, so as to obtain the matching of the dielectric constant.

Figure 26 shows the theoretical calculation values of the average electronic polarizability (α _electronic ), the average ion polarizability (α _ionic ), and the average total polarizability (α _total ) of α-phase Sb ₂ O _{3 single crystal films with different layers.} And the dielectric constant value (k) calculated based on the average total polarization, and compared with the dielectric constant of silicon dioxide.

Fig. 27 is a schematic diagram of a metal-insulator-metal (MIM) device for testing breakdown strength, in which the insulator is an α-phase Sb ₂ O ₃ nanosheet.

Fig. 28 is a scanning electron microscope image of an α-phase Sb ₂ O _{3 nanosheet MIM device.}

FIG. 29 is the breakdown current density (J) vs. voltage (V) curve of 6 representative MIM devices made of _{Sb 2} O ₃ nanosheets of different thicknesses synthesized in Example 1. Each inset: Atomic force microscope height measurement diagram used to measure the thickness of nanosheets, ruler: 3μm.

FIG 30 nanometers with Sb ₂ O ₃ diagram the breakdown field strength E _B nanosheet thickness and the measured MIM device 17 as a sheet made of α, and compared to the common low dielectric constant material.

Figure 31 is an optical microscope image of a MIM device made of _{α-phase Sb 2} O _{3 nanosheets after breakdown.}

FIG. 32 is an optical microscope image of the α-phase Sb ₂ O ₃ nanosheets synthesized in Example 1 transferred to the prefabricated circular hole substrate.

Figure 33 is a linear fitting diagram of the nanoindentation test results of 23 nanosheets.

Figure 34 is a graph showing the relationship between load and thickness when 16 nanosheets are broken, and a graph of the relationship between fracture strain and thickness simulated by finite element based on the breaking load and Young's modulus.

In Figure 4:

1. Low dielectric constant material 1 2. Low dielectric constant material 2 3. Copper interconnection (second layer metal)

4. Copper interconnection (via layer) 5. Copper interconnection (first layer of metal) 6. Metal tungsten

7. Isolation trench 8. Source 9. Drain

10. Grid 11, Back road 12. Middle road

13, front road

In Figure 5:

14. Raw material cavity 15. Substrate 16. Gas source

17. Proton flowmeter 18. Mechanical pump

In Figure 27:

19. Antimony trioxide material 20. Ti/Au electrode 21. Silicon dioxide substrate

detailed description

The present invention focuses on the development of a new, more stable, and lower dielectric constant dielectric material. For new low dielectric constant materials, the following indicators must be met:

Index 1: The dielectric constant (k) is less than 2.5, meeting the future technology nodes below 10nm. The dielectric constant is defined as k=C _x /C ₀ ; it is the capacitance of the dielectric material inserted between the two parallel plate electrodes (C _x ), divided by the capacitance of the vacuum between the two parallel plate electrodes (C ₀ ). The experiment can be obtained from commercial scanning microwave impedance microscope measurement.

Index 2: wide band gap (E _g )>4eV. It can be obtained by ultraviolet spectrophotometry in experiments.

Index 3: Can withstand high temperature of 400℃.

Index 4: Breakdown field strength (E _B ) is greater than 1MV/cm. The breakdown field strength is defined as E _B =V _B /d; it is defined as the breakdown electric field (V _B ) of two parallel plate electrodes inserted into the dielectric material, divided by the distance between the two electrodes, that is, the thickness of the dielectric material (d). In experiments, metal-insulator-metal (MIM) devices can be used to measure the "current density-voltage" characteristic curve, define the measured breakdown electric field, and use an atomic force microscope to measure the thickness of the dielectric material.

Index 5: Young's modulus (E) is greater than 1 GPa, and the mechanical strength is greater than 0.2 GPa. Young's modulus is defined as E=σ/ε; it is the normal stress σ applied to the material, divided by the normal strain ε generated by the material.

In the present invention, the applicant unexpectedly discovered through a large number of experiments that the inorganic oxide antimony trioxide material is a new type of low-dielectric constant material with excellent performance, meeting the above five indicators, and can be used as an interlayer or intermetallic semiconductor integrated circuit The application of dielectric materials. The antimony trioxide material is α-phase antimony trioxide, commonly known as cristobalite, antimony white, etc., and its English name is Senarmontite. It is a cubic crystal assembled by tetraantimony hexaoxide (Sb ₄ O ₆ ) adamantane-like cage molecules (as shown in Figure 3).

The inorganic oxide described in the present invention, namely antimony trioxide material, can be used for the "interlayer dielectric material (Interlayer Dielectric)" and the "layer isolation dielectric material (Dielectric Cap)" between the metals in the integrated circuit . The interlayer dielectric material (Interlayer Dielectric) and the layer isolation dielectric material (Dielectric Cap) are used in electronic chips. They are a multi-layer, complex circuit structure formed by filling metal wires and dielectric materials prepared by the subsequent process. The "Interlayer Dielectric" used between metals is usually a traditional silicon dioxide material, or it can be a composite of the antimony trioxide material and/or the antimony trioxide material and the air gap according to the present invention Structure. In the multi-layer and complex metal wire circuits of electronic chips, "filling dielectric material" usually refers to the filling material used in each single-layer metal circuit. The filling material between the metal wires plays a role of insulation between circuits. And low-k dielectric materials. For example, the above-mentioned metal materials may usually be traditional aluminum materials or copper metals used in advanced technologies, and the dielectric materials located between the aluminum metal wires or the copper metal wires can obviously play the role of insulation and low-k.

The "Dielectric Cap" used for the interlayer is usually a traditional silicon dioxide material, or the antimony trioxide material described in the present invention, and/or the antimony trioxide material and air gaps In the multi-layer and complex metal wire circuits of electronic chips, the "layer isolation dielectric material" usually refers to the insulating material applied between the single-layer circuit and the single-layer circuit, which plays the role of insulation between circuits and low k-action dielectric material. For example, the above-mentioned metal materials may usually be traditional aluminum materials or copper metals used in advanced technologies. The dielectric material between the single-layer circuit and the single-layer circuit can obviously play the role of insulation and low-k.

In a specific embodiment of the present invention, as shown in FIG. 2. Specifically, in the enlarged schematic cross-sectional view of a logic device shown in FIG. 4, between the metal and the metal (that is, the copper wire and the copper wire), "dielectric constant material 1" is required as the in-layer filling dielectric material; Between layers, "dielectric constant material 2" is required as the layer isolation dielectric material. In the present invention, the α-phase antimony trioxide material can be used as a dielectric material between semiconductor IC layers, specifically, it can be used as "dielectric constant material 1" and "dielectric constant material 2".

For a long time, the α-phase antimony trioxide has been mainly used as a flame retardant synergist, an additive for lubricants, as a covering agent and brightener in enamel and ceramic products, or as a heavy oil, residual oil, catalytic cracking, and catalytic heavy oil in petroleum. The passivation agent in the whole process and the excellent white inorganic pigments are widely used. The annual consumption of Sb ₂ O ₃ is about 150,000 tons, and the price in recent years is about 18,000 yuan per ton. The reserves are relatively abundant and the price is low. The invention uses the material as a dielectric material between semiconductor integrated circuit layers or between metals, which is a brand-new application. At present, the dielectric materials mainly used for low dielectric constant materials between IC layers in the industry are materials derived from silicon dioxide, and the materials of the present invention can replace the original traditional dielectric constant materials, and meet the requirements of technical nodes below 10nm. The requirements of the electrical constant further effectively improve the calculation speed and performance of the chip, achieving breakthroughs and innovations. In the present invention, the inorganic oxide antimony trioxide material is innovatively applied to the dielectric material between semiconductor integrated circuit layers or between metals, and has the potential to create significant commercial value.

The present invention provides the application of antimony trioxide material as a dielectric material between semiconductor integrated circuit layers or between metals. The antimony trioxide material is a molecular crystal formed by Sb ₄ O ₆ cage-like molecules connected by van der Waals forces. Form a two-dimensional or three-dimensional structure. Sb ₄ O ₆ cage-like molecules self-assemble through van der Waals forces to form a two-dimensional or three-dimensional structure. Specifically, the interlayer or intermetal dielectric material of the constructed semiconductor integrated circuit includes antimony trioxide, and the interlayer or intermetal dielectric material of the constructed semiconductor integrated circuit also includes antimony trioxide and air. The composite structure of the gap. The antimony trioxide material is a molecular crystal, which is a two-dimensional or three-dimensional structure formed by connecting _{Sb 4} O _{6 cage-like molecules through van der Waals forces.}

In the application of the antimony trioxide material provided by the present invention as a dielectric material between semiconductor integrated circuit layers or between metals, the antimony trioxide material is α-phase antimony trioxide, which is passed through a horizontal single-temperature zone vacuum tube Furnace synthesis system synthesis, as shown in Figure 5. It should be noted that the growth method of the α-phase antimony trioxide material is not limited to the vacuum tube furnace method.

在(111)面上表现由类金刚烷笼子状的Sb ₄O ₆分子通过范德华力自组装形成的二维结构，如图7和图8所示。由Sb ₄O ₆笼状分子通过范德华力自组装，也可形成立体三维颗粒结构，如图9和图10。所述α相三氧化二锑的

晶面间距为

在一些实施方式中，所述α相三氧化二锑的

晶面间距也可以为

或

等。 In the application of the antimony trioxide material provided by the present invention as a dielectric material between semiconductor integrated circuit layers or between metals, the antimony trioxide material is preferably α-phase antimony trioxide, which is a cubic crystal system and belongs to space 227 group

On the (111) plane, _{a two-dimensional structure formed by self-assembly of adamantane cage-like Sb 4} O ₆ molecules through van der Waals forces is shown, as shown in Figs. 7 and 8. Self-assembly of Sb ₄ O ₆ cage-like molecules through van der Waals forces can also form a three-dimensional three-dimensional particle structure, as shown in Figs. 9 and 10. The α-phase antimony trioxide

Interplanar spacing is

In some embodiments, the α-phase antimony trioxide is

Interplanar spacing can also be

or

Wait.

In the application of the antimony trioxide material provided by the present invention as a dielectric material between semiconductor integrated circuit layers or between metals, the morphology of the antimony trioxide material is triangular nano-sheets. In a specific embodiment, the shape of the nanosheet single crystal of antimony trioxide material is an equilateral triangle, and the side length of the nanosheet is between 0.1-30 μm, as shown in FIGS. 7 and 8. In some embodiments, the side lengths of the nanosheets are 0.1 to 1 μm, 1 to 5 μm, 5 to 10 μm, 10 to 15 μm, 15 to 20 μm, 20 to 25 μm, 25 to 30 μm, 1 to 28 μm, 5 to 25 μm , 8-22μm, 10-25μm, 15-25μm, or 18-22μm, etc.

In the application of the antimony trioxide material provided by the present invention as a dielectric material between semiconductor integrated circuit layers or between metals, the thickness of the nanosheets of the two-dimensional antimony trioxide material is 0.6 nm to 2000 nm, as shown in FIG. 11 . In some specific embodiments, the thickness of the nanosheets of the two-dimensional antimony trioxide material is 0.6 nm to 10 nm, 10 nm to 100 nm, 100 nm to 200 nm, 200 nm to 300 nm, 300 nm to 400 nm, 400 nm to 500 nm, 500 nm to 600 nm. , 600nm～700nm, 700nm～800nm, 800nm～900nm, 900nm～1000nm, 1000nm～1200nm, 1200nm～1400nm, 1400nm～1600nm, 1600nm～1800nm, 1800nm～2000nm, 1nm～1900nm, 10nm～1800nm, 50nm～1700nm, 100nm ～1600nm, 200nm～1500nm, 300nm～1400nm, 400nm～1300nm, 500nm～1300nm, 600nm～1200nm, 700nm～1100nm, or 800nm～1000nm, etc.

In the application of the antimony trioxide cage-like molecular crystal provided by the present invention as a dielectric material between semiconductor integrated circuit layers or between metals, the morphology of the single crystal of the antimony trioxide molecule can also be an octahedral crystal grain , As shown in Figure 9 and Figure 10.

In the application of the antimony trioxide material provided by the present invention as a dielectric material between semiconductor integrated circuit layers or between metals, the optical band gap of the antimony trioxide material is 5.5～5.7eV, 5.5～5.6eV, or 5.6～5.7eV etc. The dielectric constant of the antimony trioxide material is 1.8-2.5, 1.8-1.9, 1.9-2.0, 2.0-2.1, 2.1-2.2, 2.2-2.3, 2.3-2.4, 2.4-2.5, 1.9-2.5, 2.0- 2.4, or 2.1 to 2.3, etc. The breakdown field strength of the antimony trioxide material is 1.4～2.5MV/cm, 1.4～1.6MV/cm, 1.6～1.8MV/cm, 1.8～2.0MV/cm, 2.0～2.2MV/cm, 2.2～ 2.4MV/cm, 2.4～2.5MV/cm, 1.5～2.4MV/cm, 1.6～2.3MV/cm, 1.7～2.2MV/cm, or 1.8～2.1MV/cm, etc. The Young's modulus of the antimony trioxide material is 14.4-16GPa, 14.4-15.2GPa, 15.2-16GPa, 14.4-14.8GPa, 14.8-15.2GPa, 15.2-15.6GPa, 15.6-16GPa, 14.4-15.0GPa, Or 15.0～16GPa, etc. The mechanical strength of the antimony trioxide material is 0.93-1.32 GPa, 0.93 to 1.0 GPa, or 1.0 to 1.32 GPa, and the like.

In the application of the antimony trioxide material provided by the present invention as a dielectric material between semiconductor integrated circuit layers or between metals, the antimony trioxide material has a dielectric constant of 1.8-2.5 and an optical band gap of 5.5-5.7 eV, breakdown field strength is 1.4～2.5MV/cm, can withstand high temperature above 550℃, Young's modulus is 14.4～16GPa, mechanical strength is a new type of low dielectric constant material with 0.93～1.32GPa.

The synthesis method of antimony trioxide material in the present invention will be described in detail as follows:

Another aspect of the present invention provides a method for preparing the antimony trioxide material used in the foregoing process of the present invention, including: using (1) antimony trioxide powder or (2) under vacuum conditions and an inert gas and/or oxygen atmosphere Metal antimony powder is used as the reaction source, and antimony trioxide materials with the same crystal structure, uniform composition and defect-free can be obtained by depositing on the substrate. The representative results of component analysis are shown in Figure 12 and Figure 13; the representative results of single crystal crystallinity are shown in Figure 14, Figure 15, Figure 16, and Figure 17. Specifically, under vacuum conditions and an inert gas atmosphere, after the antimony trioxide powder is heated and volatilized, the antimony trioxide material is deposited on the substrate; and/or, under vacuum conditions and an oxygen plus inert gas atmosphere, the metal antimony After the powder is heated to volatilize and react with oxygen, the antimony trioxide material is obtained by deposition on the substrate.

In the preparation method of antimony trioxide material, the vacuum conditions for the synthesis of the material, that is, the pressure in the reaction is 3～500 Torr; 3～60 Torr, 60～100 Torr, 100～200 Torr, 200～300 Torr, 300～400 Torr, 400～ 500 Torr, 3-15 Torr, or 15-100 Torr, etc. The inert gas is argon and/or nitrogen, preferably argon. The synthesis reaction temperature is 320-700°C, 320-450°C, 450-650°C, 320-380°C, 380-600°C, 600-650°C, or 650-700°C, etc.

In the preparation method of antimony trioxide material, specifically, under vacuum conditions and an inert gas and/or oxygen atmosphere, the raw materials of high-purity antimony trioxide powder and/or metal antimony powder are heated and volatilized, and are deposited on the substrate Depositing to obtain antimony trioxide material. The substrate may be, for example, a substrate having an atomic level flat surface. Specifically, the substrate is selected from one or more combinations of mica, silicon dioxide, graphene, sapphire, and the like. Preferably, the substrate may be mica, for example. In a specific embodiment, the antimony trioxide material is α-phase antimony trioxide.

In the embodiment using antimony trioxide powder as a raw material, the preparation method of the antimony trioxide material includes: the antimony trioxide powder as a raw material reacts and volatilizes under vacuum conditions and in an inert gas and oxygen atmosphere, and lining The two-dimensional α-phase antimony trioxide is prepared on the bottom. Specifically, under normal circumstances, it is necessary to pump the background vacuum below 5×10 ^-2 Torr, and then pass in inert gas of 30～300sccm, 3～60 Torr, 60～100 Torr, 100～200 Torr, or 200～300 Torr. For example, it can be argon gas, which is repeatedly pumped and ventilated to exhaust impurity gas. Then pass in 0～50sccm, 1～50sccm, 1～15sccm, 15～30sccm, or 30～50sccm of high purity oxygen and 10～300sccm, 10～50sccm, 50～100sccm, 10～200sccm, or 200～300sccm. Pure argon, and keep the pressure inside the tube at 3-60 Torr, 3-10 Torr, 10-20 Torr, 20-30 Torr, 30-40 Torr, 40-50 Torr, or 50-60 Torr, etc. At a temperature of 320～450℃, 320～380℃, 380～400℃, or 400～450℃, etc., and keep it for 10～180min, 10～60min, 60～100min, 100～120min, 120～150min, or 150～ 180min and so on. After that, it is naturally cooled, and then the pumping is stopped, and the pressure is restored to normal atmospheric pressure, and the substrate is collected to obtain _{nanosheets of two-dimensional α-phase Sb 2} O ₃ molecular crystals. Further, the above-mentioned reaction can be carried out in a horizontal single-temperature zone vacuum tube furnace synthesis system as shown in FIG. 5. Furthermore, first put 5-20mg, 5-10mg, 10-15mg, or 15-20mg of high-purity antimony trioxide powder (α-phase Sb ₂ O ₃ ) into the quartz boat and place it in the tube furnace Place the substrate at the center of the quartz tube (for example, it can be 1 inch in diameter and 1 meter in length) downstream of the gas flow in the tube at a distance of 15-30 cm, 15-20 cm, or 20-30 cm from the powder material, and then assemble and seal the device. The vacuum step will be carried out, and then inert gas and oxygen will be introduced to react. Among them, oxygen is used as the oxidation reaction gas.

In the embodiment using metal antimony powder as a raw material, the preparation method of the antimony trioxide material includes: metal antimony powder as a raw material reacts, volatilizes and reacts under vacuum conditions and an inert gas and oxygen atmosphere, and prepares it on a substrate Obtain two-dimensional α-phase antimony trioxide. Specifically, under normal circumstances, it is necessary to pump the background vacuum below 5×10 ^-2 Torr, and then pass in inert gas of 30～300sccm, 3～60 Torr, 60～100 Torr, 100～200 Torr, or 200～300 Torr. For example, it can be argon gas, which is repeatedly pumped and ventilated to exhaust impurity gas. Then pass 0～50sccm, 1～50sccm, 1～15sccm, 15～30sccm, or 30～50sccm of high purity oxygen and 10～200sccm, 10～50sccm, 50～100sccm, 10～200sccm of high purity argon, and Keep the pressure inside the tube at 15-100 Torr, 15-30 Torr, 30-60 Torr, 60-80 Torr, or 80-100 Torr, etc. At a temperature of 380～600℃, 380～420℃, 420～450℃, 450～500℃, 500～550℃, or 550～600℃, etc., and keep it for 10～180min, 10～60min, 60～100min, 100 ～120min, 120～150min, or 150～180min, etc. After that, it is naturally cooled, and then the pumping is stopped, and the pressure is restored to normal atmospheric pressure, and the substrate is collected to obtain _{nanosheets of two-dimensional α-phase Sb 2} O ₃ molecular crystals. Further, the above-mentioned reaction can be carried out in a horizontal single-temperature zone vacuum tube furnace synthesis system as shown in FIG. 5. Furthermore, first put 5-20mg, 5-10mg, 10-15mg, or 15-20mg of high-purity metal antimony powder into a quartz boat and place it in a quartz tube (for example, 1 inch in diameter, The length is 1 meter), and then place the substrate at a position 15-30cm, 15-20cm, or 20-30cm from the powder material downstream of the gas flow in the tube, assemble the sealed device, and then vacuumize, and then inert gas React with oxygen.

It should be noted that: 1) The conditions determined by the above method are determined by the device shown in Figure 5, but other equipment can create nanosheets with the same composition and structure or continuous thin films formed by stacking nanosheets. . 2) The substrate used in this method can be mica, silica flakes, graphene, etc., preferably freshly exfoliated mica. The size of the substrate is about 1.5×5 cm. 3) In the embodiment using antimony trioxide powder as the raw material, oxygen provides an oxidizing environment to prevent the Sb ₂ O ₃ material from being reduced; while in the embodiment using metal antimony powder as the raw material, oxygen is used as the oxidant to make gasification The antimony atoms are oxidized into Sb ₄ O ₆ cage-like molecules. In the two embodiments, argon is used as the transport gas, mainly to transport the vaporized Sb ₄ O ₆ cage molecules to the downstream of the gas flow and deposit on the substrate. 4) The parameters indicated in the range provided in the details are the preferred parameter ranges. Within this range, α-phase Sb ₂ O ₃ materials can be synthesized only in morphology, such as the formation of nanosheets with different thicknesses or by The nanosheets are stacked to form a thin film, and there is no difference in physical and chemical properties. Adjusting the parameters within the provided range mainly affects the size and thickness of the synthesized sample.

The preparation method of the antimony trioxide material provided by the present invention can also adopt plasma chemical vapor deposition (PECVD) and vapor atomic layer deposition (ALD).

The single crystal shape of the antimony trioxide material provided by the present invention is a three-dimensional structure of octahedral crystal grains. In the method for synthesizing the single crystal shape of the antimony trioxide material as octahedral crystal grains, according to the above-mentioned differences In the two synthesis methods using antimony trioxide and metallic antimony as raw materials, increase the synthesis temperature and pressure beyond the stated range. For example, in the embodiment using antimony trioxide as the raw material, set the synthesis temperature to 450-600 ℃, 450～500℃, 500～550℃, or 550～600℃. During synthesis, keep the pressure inside the tube at 90-300 Torr, 90-120 Torr, 120-160 Torr, 160-200 Torr, 200-250 Torr, or 250-300 Torr. Particles with a particle size of 1～6μm, 1～3μm, or 3～6μm can be obtained; or set the synthesis temperature to 600～700℃, 600～650℃, or 650～700 in the embodiment using metal antimony as the raw material ℃, keep the pressure inside the tube at 150-500 Torr, 150-250 Torr, 250-300 Torr, 300-400 Torr, or 400-500 Torr during synthesis. Particles with a particle size of 5-10μm, 5-8μm, or 8-10μm can be obtained.

Another aspect of the present invention provides the application of a composite structure of antimony trioxide material and air voids between semiconductor integrated circuit layers or between metals, especially the application of dielectric layers between metals. The antimony trioxide material is the antimony trioxide material described in the first aspect of the present invention.

The composite structure of antimony trioxide material and air void provided by the present invention is used in the application of semiconductor integrated circuit metal. The resulting film is a continuous film, as shown in Figure 18 and Figure 19. This type of film has irregular voids, among which the air voids in the film are generated by stacking triangular nanosheets. The composite structure composed of antimony trioxide and air voids, as shown in Figure 20, is also a new type of low dielectric constant material. In the composite structure, the volume ratio of antimony trioxide and air voids is between 5:1 and 100:1. In some specific embodiments, the volume ratio of antimony trioxide and air voids may be 5:1-100:1, 5:1-20:1, 20:1-40:1, 40:1-60:1 , 60:1～80:1, 80:1～100:1, 10:1～90:1, 20:1～80:1, 30:1～70:1, or 40:1～60:1, etc. .

In the application of the composite structure of antimony trioxide material and air voids provided by the present invention in the intermetallic applications of semiconductor integrated circuits, the morphology of the composite structure of antimony trioxide material and air voids can also be octahedral crystal grains. Or a film formed by the accumulation of octahedral crystal grains. The film is a continuous film with air voids in the film; the air voids are irregular voids. The air voids in the film are generated by stacking octahedral crystal grains. In the composite structure, the volume ratio of antimony trioxide and air voids is between 5:1 and 100:1. In some specific embodiments, the volume ratio of antimony trioxide and air voids may be 5:1-100:1, 5:1-20:1, 20:1-40:1, 40:1-60:1 , 60:1～80:1, 80:1～100:1, 10:1～90:1, 20:1～80:1, 30:1～70:1, or 40:1～60:1, etc. .

The synthesis method of the composite structure of antimony trioxide material and air gap is:

In the preparation method of the antimony trioxide material and the air gap composite structure, specifically, the high-purity antimony trioxide powder and/or metal antimony powder raw materials are heated and volatilized under vacuum conditions and an inert gas and/or oxygen atmosphere , Mainly through excessive reaction, mainly to increase the time or reaction concentration to increase the amount of triangular or octahedral crystal grains deposited on the substrate, so as to become a continuous film, in the triangular or octahedral crystal grain stacking process, irregular The voids can be formed naturally, and finally a new composite structure of antimony trioxide and air voids is obtained.

In the embodiment using antimony trioxide powder as the raw material, the preparation method of the antimony trioxide material and the air gap composite structure includes: the antimony trioxide powder is used as the raw material to react and heat under vacuum conditions and an inert gas and oxygen atmosphere. It volatilizes, and prepares a continuous film formed by stacking nano-sheets on a substrate, that is, a composite structure of antimony trioxide material and air gaps. Specifically, under normal circumstances, it is necessary to evacuate the background vacuum below 5×10 ^-2 Torr, and then pass in an inert gas of 30 to 300 sccm, such as argon, and repeatedly evacuate and vent to exhaust impurity gases. Then pass in 0～50sccm of high purity oxygen and 10～300sccm, 3～60Torr, 60～100Torr, 100～200Torr, or 200～300Torr of high purity argon, and keep the pressure inside the tube at 3～60Torr, 3～10Torr , 10-20 Torr, 20-30 Torr, 30-40 Torr, 40-50 Torr, or 50-60 Torr. At a temperature of 320～450℃, 320～380℃, 380～400℃, or 400～450℃ and keep for 120～240min, 120～150min, 150～180min, 180～200min, 200～220min, or 220～240min. After that, it cools naturally, then stops pumping, returns to normal atmospheric pressure, collects the substrate, and obtains a continuous film formed by increasing the growth time to cause the accumulation of nanosheets.

Further, the above-mentioned reaction can be carried out in a horizontal single-temperature zone vacuum tube furnace synthesis system as shown in FIG. 5. Furthermore, first put 5-20mg, 5-10mg, 10-15mg, or 15-20mg of high-purity antimony trioxide powder (α-phase Sb ₂ O ₃ ) into the quartz boat and place it in the tube furnace Place the substrate at the center of the quartz tube (for example, it can be 1 inch in diameter and 1 meter in length) downstream of the gas flow in the tube at a distance of 15-30 cm, 15-20 cm, or 20-30 cm from the powder material, and then assemble and seal the device. The vacuum step will be carried out, and then inert gas and oxygen will be introduced to react. Among them, oxygen is used as the oxidation reaction gas.

In the embodiment using metal antimony powder as the raw material, the preparation method of the antimony trioxide material and the air gap composite structure includes: the metal antimony powder as the raw material reacts, volatilizes and reacts under vacuum conditions and an inert gas and oxygen atmosphere, and A continuous thin film formed by stacking nano-sheets is prepared on the substrate, that is, a composite structure of antimony trioxide material and air gaps. Specifically, under normal circumstances, it is necessary to pump the background vacuum below 5×10 ^-2 Torr, and then pass in inert gas of 30～300sccm, 3～60 Torr, 60～100 Torr, 100～200 Torr, or 200～300 Torr. For example, it can be argon gas, which is repeatedly pumped and ventilated to exhaust impurity gas. Then pass in 0～50sccm, 1～50sccm, 1～15sccm, 15～30sccm, or 30～50sccm of high purity oxygen and 10～200sccm, 10～50sccm, 50～100sccm, 10～200sccm, high purity argon, And keep the pressure inside the tube at 15-100 Torr, 15-30 Torr, 30-60 Torr, 60-80 Torr, or 80-100 Torr. At the temperature of 380～600℃, 380～420℃, 420～450℃, 450～500℃, 500～550℃, or 550～600℃ and keep for 120～240min, 120～150min, 150～180min, 180～200min , 200～220min, or 220～240min. After that, it cools naturally, then stops pumping, returns to normal atmospheric pressure, collects the substrate, and obtains a continuous film formed by increasing the growth time to cause the accumulation of nanosheets. Further, the above-mentioned reaction can be carried out in a horizontal single-temperature zone vacuum tube furnace synthesis system as shown in FIG. 5. Furthermore, first put 5-20mg, 5-10mg, 10-15mg, or 15-20mg of high-purity metal antimony powder into a quartz boat and place it in a quartz tube (for example, 1 inch in diameter, The length is 1 meter), and then place the substrate at a position 15-30cm, 15-20cm, or 20-30cm from the powder material downstream of the gas flow in the tube, assemble the sealed device, and then vacuumize, and then inert gas React with oxygen.

The beneficial effects of the present invention are as follows:

The invention discloses a kind of antimony trioxide material with ultra-low dielectric constant, high temperature thermal stability and electrical breakdown resistance, wide energy band gap and strong mechanical properties, which can be applied to the interlayer of semiconductor integrated circuits. Electric materials. Can reduce the interconnection delay restriction in the integrated circuit. In addition, a proof-of-concept device was used to verify the feasibility of the material as an interlayer dielectric material for semiconductor integrated circuits.

The following describes the implementation of the present invention through specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the process equipment or devices not specifically noted in the following embodiments all adopt conventional equipment or devices in the art. In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude that there may be other method steps before and after the combined steps or other method steps may be inserted between these explicitly mentioned steps, unless otherwise stated. It should be noted; it should also be understood that the combined connection relationship between one or more devices/devices mentioned in the present invention does not exclude that other devices/devices may also exist before and after the combined device/device or are explicitly mentioned in these Other devices/devices can also be inserted between the two devices/devices, unless otherwise specified. Moreover, unless otherwise specified, the number of each method step is only a convenient tool for identifying each method step, not to limit the sequence of each method step or to limit the scope of implementation of the present invention. The change or adjustment of the relative relationship is If there is no substantial change in the technical content, it shall be regarded as the scope of the implementation of the present invention.

In the following examples, the reagents, materials, and instruments used are all commercially available unless otherwise specified.

Example 1:

Preparation of two-dimensional α-phase Sb ₂ O ₃ molecular crystal nanosheets

(1) The synthesis equipment adopts the horizontal single-temperature zone vacuum tube furnace synthesis system as shown in Figure 5. First put 15mg of high-purity antimony trioxide powder (α-phase Sb ₂ O ₃ powder) into the quartz boat, place it in the center of the quartz tube of the tube furnace, and then place the lining at a position 17 cm away from the powder raw material downstream of the gas flow in the tube Bottom, assemble and seal the device. Subsequently, the background vacuum was evacuated below 5×10 ^-2 Torr, and 100 sccm of high-purity argon gas was introduced for 3 minutes without controlling the pressure in the tube, and then the background vacuum was evacuated below 5×10 ^-2 Torr. Repeatedly pump and ventilate at least twice to expel the impurity gas in the quartz tube.

(2) Pass in 0 sccm of high purity oxygen and 300 sccm of high purity argon, and keep the pressure inside the tube at 3 Torr. After the pressure in the belt tube is stable, the tube furnace is heated to the synthesis temperature of 360°C and maintained for 45 minutes, and the furnace body is naturally cooled to room temperature after the heat preservation is completed. Then stop pumping to return the tube to normal atmospheric pressure, collect the substrate, and obtain two-dimensional α-phase Sb ₂ O ₃ molecular crystal nanosheets, as shown in FIG. 7, the density of the nanosheets is related to the growth time. The representative results of component analysis of Example 1 are shown in Figs. 12 and 13; the representative results of single crystal crystallinity are shown in Fig. 14, Fig. 15, and Fig. 16.

Example 2:

Preparation of two-dimensional α-phase Sb ₂ O ₃ molecular crystal nanosheets

(1) The synthesis equipment adopts the horizontal single-temperature zone vacuum tube furnace synthesis system as shown in Figure 5. Firstly, 15 mg of high-purity metal antimony powder (Sb) is loaded into the quartz boat, placed in the center of the quartz tube of the tube furnace, and then the substrate is placed at a position 20 cm from the powder raw material downstream of the gas flow in the tube, and the sealed device is assembled. Subsequently, the background vacuum was evacuated below 5×10 ^-2 Torr, and 100 sccm of high-purity argon gas was introduced for 3 minutes without controlling the pressure in the tube, and then the background vacuum was evacuated below 5×10 ^-2 Torr. Repeatedly pump and ventilate at least twice to expel the impurity gas in the quartz tube.

(2) Pass 20 sccm of high-purity oxygen gas and 100 sccm of high-purity argon gas, and keep the pressure inside the tube at 15 Torr. After the pressure in the belt tube is stabilized, the tube furnace is heated to a synthesis temperature of 400°C and maintained for 45 minutes, and the furnace body is naturally cooled to room temperature after the heat preservation is completed. Then stop pumping, return the tube to normal atmospheric pressure, collect the substrate, and obtain two-dimensional α-phase Sb ₂ O ₃ molecular crystal nanosheets, as shown in FIG. 8, the density of the nanosheets is related to the growth time. The composition and crystallinity results of Example 2 are not significantly different from those of Example 1, and they are all α-phase Sb ₂ O ₃ with uniform composition and ultra-high purity without impurities.

Example 3:

Preparation of octahedral particles of three-dimensional α-phase Sb ₂ O _{3 molecular crystals}

(1) The synthesis equipment adopts the horizontal single-temperature zone vacuum tube furnace synthesis system as shown in Figure 5. First, put 20mg of high-purity antimony trioxide powder (α-phase Sb ₂ O ₃ powder) into the quartz boat, place it in the center of the quartz tube of the tube furnace, and then place the lining at a position 15 cm from the powder raw material downstream of the gas flow in the tube Bottom, assemble and seal the device. Subsequently, the background vacuum was evacuated below 5×10 ^-2 Torr, and 100 sccm of high-purity argon gas was introduced for 3 minutes without controlling the pressure in the tube, and then the background vacuum was evacuated below 5×10 ^-2 Torr. Repeatedly pump and ventilate at least twice to expel the impurity gas in the quartz tube.

(2) Pass 0sccm of high-purity oxygen and 300sccm of high-purity argon, and keep the pressure in the tube at 150 Torr. After the pressure in the belt tube is stable, the tube furnace is heated to a synthesis temperature of 500°C and maintained for 30 minutes, and the furnace body is naturally cooled to room temperature after the heat preservation is completed. Then stop pumping, return the tube to normal atmospheric pressure, collect the substrate, and obtain particles with a particle size of 2 to 4 μm, that is, octahedral particles of _{three-dimensional α-phase Sb 2} O _{3 molecular crystals.} The morphology of Example 3 is shown in Fig. 9 and the crystallinity result is shown in Fig. 17. The composition result is not significantly different from that of Example 1. Both are homogeneous, ultra-high purity α-phase Sb ₂ O ₃ without impurities.

Example 4:

Preparation of octahedral particles of three-dimensional α-phase Sb ₂ O _{3 molecular crystals}

(1) The synthesis equipment adopts the horizontal single-temperature zone vacuum tube furnace synthesis system as shown in Figure 5. First, 20 mg of high-purity metal antimony powder (Sb) is loaded into the quartz boat, placed in the center of the quartz tube of the tube furnace, and then the substrate is placed at a position 15 cm from the powder raw material downstream of the airflow in the tube, and the sealed device is assembled. Subsequently, the background vacuum was evacuated below 5×10 ^-2 Torr, and 100 sccm of high-purity argon gas was introduced for 3 minutes without controlling the pressure in the tube, and then the background vacuum was evacuated below 5×10 ^-2 Torr. Repeatedly pump and ventilate at least twice to expel the impurity gas in the quartz tube.

(2) Pass 20 sccm of high-purity oxygen and 100 sccm of high-purity argon, and keep the pressure inside the tube at 200 Torr. After the pressure inside the belt tube is stable, the tube furnace is heated to the synthesis temperature of 650°C and kept for 20 minutes, and the furnace body is allowed to cool to room temperature naturally after the heat preservation is completed. Then stop pumping, return the tube to normal atmospheric pressure, collect the substrate, and obtain two-dimensional α-phase Sb ₂ O ₃ molecular crystal nanosheets. Particles with a particle size of 6-9 μm can be obtained, that is, octahedral particles of _{three-dimensional α-phase Sb 2} O _{3 molecular crystals.} The morphology of Example 4 is shown in Fig. 10, and the composition and structure results are not significantly different from those of Example 3. They are all α-phase Sb ₂ O ₃ with uniform composition and ultra-high purity without impurities. .

Example 5:

Preparation of composite structure of antimony trioxide material and air voids

(1) The synthesis equipment adopts the horizontal single-temperature zone vacuum tube furnace synthesis system as shown in Figure 5. First put 15mg of high-purity antimony trioxide powder (α-phase Sb ₂ O ₃ powder) into the quartz boat, place it in the center of the quartz tube of the tube furnace, and then place the lining at a position 25 cm from the powder raw material downstream of the gas flow in the tube Bottom, assemble and seal the device. Subsequently, the background vacuum was evacuated below 5×10 ^-2 Torr, and 100 sccm of high-purity argon gas was introduced for 3 minutes without controlling the pressure in the tube, and then the background vacuum was evacuated below 5×10 ^-2 Torr. Repeatedly pump and ventilate at least twice to expel the impurity gas in the quartz tube.

(2) Pass 15 sccm of high-purity oxygen and 50 sccm of high-purity argon, and keep the pressure in the tube at 50 Torr. After the pressure inside the belt tube is stable, the tube furnace is heated to a synthesis temperature of 400°C and maintained for 120 minutes, and the furnace body is naturally cooled to room temperature after the heat preservation is completed. Then stop pumping, return the tube to normal atmospheric pressure, collect the substrate, and obtain _{a continuous film formed by stacking two-dimensional α-phase Sb 2} O ₃ molecular crystal nanosheets, that is, the antimony trioxide material and air are caused by increasing the growth time. Composite structure of voids. The morphology of Example 5 is shown in Fig. 18, and the results of composition and crystallinity are not significantly different from those of Example 1. They are all α-phase Sb ₂ O ₃ with uniform composition and ultra-high purity without impurities.

Example 6:

Synthesis of composite structure of antimony trioxide material and air void

(1) The synthesis equipment adopts the horizontal single-temperature zone vacuum tube furnace synthesis system as shown in Figure 5. First, put 10mg of high-purity metal antimony powder (Sb) into the quartz boat, place it in the center of the quartz tube of the tube furnace, and then place the substrate at a position 25cm from the powder raw material downstream of the airflow in the tube, and assemble the sealed device. Subsequently, the background vacuum was evacuated below 5×10 ^-2 Torr, and 100 sccm of high-purity argon gas was introduced for 3 minutes without controlling the pressure in the tube, and then the background vacuum was evacuated below 5×10 ^-2 Torr. Repeatedly pump and ventilate at least twice to expel the impurity gas in the quartz tube.

(2) Pass 20 sccm of high-purity oxygen gas and 50 sccm of high-purity argon gas, and keep the pressure inside the tube at 50 Torr. After the pressure in the belt tube is stable, the tube furnace is heated to a synthesis temperature of 450°C and maintained for 120 minutes, and the furnace body is naturally cooled to room temperature after the heat preservation is completed. Then stop pumping, return the tube to normal atmospheric pressure, collect the substrate, and obtain _{a continuous film formed by stacking two-dimensional α-phase Sb 2} O ₃ molecular crystal nanosheets, that is, the antimony trioxide material and air are caused by increasing the growth time. Composite structure of voids. The morphology of Example 6 is shown in Fig. 19, and the results of composition and crystallinity are not significantly different from those of Example 1. They are all α-phase Sb ₂ O ₃ with uniform composition and ultra-high purity without impurities.

Related characterization test results:

Morphology characterization results: the morphologies of the α-phase antimony trioxide nanoplatelets synthesized in Example 1 and Example 2 are shown in Figs. 7 and 8. Among them, _{the nanosheets synthesized with Sb 2} O ₃ powder raw materials can synthesize larger nanosheets, and the thickness of the nanosheets synthesized with Sb metal powder raw materials is more uniform. The measurement results of nanosheets with different thicknesses by atomic force microscopy are shown in Figure 11. The particle morphologies of the α-phase antimony trioxide synthesized in Example 3 and Example 4 are shown in FIG. 9 and FIG. 10. The morphologies of the thin films formed by stacking α-phase antimony trioxide nanosheets or particles synthesized in Example 5 and Example 6 are shown in FIG. 18 and FIG. 19.

Component analysis result: The composition characterization of the nanosheets synthesized in Example 1 shows that the α-phase antimony trioxide is composed of Sb and O elements, and X-ray fluorescence spectroscopy (XPS) shows that there is only +3 valence. Sb (see Figure 12) indicates that the synthesized product has a single composition and high purity; the element distribution diagram of X-ray energy spectrum analysis (EDS) shows that the two elements of Sb and O are evenly distributed, indicating that the sample has good crystallinity and no other defects ( See Figure 13).

晶面间距为

如图14所示，且所述α相三氧化二锑沿着[111]方向的衍射点阵只有一套，无多晶环的出现，说明合成的晶体质量高，无其他杂质相，如图15所示。用X射线衍射仪对实施例1合成的纳米片进行表征(见图16)，图谱特征峰信号强烈，且不存在宽化现象，说明合成晶体高纯单一且质量高。另外，其与标准PDF卡片对比发 现纳米片只存在(111)(222)(444)单个特征峰的信号，说明合成的α相三氧化二锑的成长方向沿着Sb ₂O ₃的(111)面生长。用X射线衍射仪对实施例3合成的颗粒进行表征(见图17)，图谱特征峰信号强烈且能够与PDF卡片一一对应，无其他杂峰，说明合成α相三氧化二锑晶体高纯单一且质量高。 Crystal structure characterization results: The nanosheets synthesized in Example 1 were characterized by a transmission electron microscope, and the α-phase antimony trioxide was measured.

Interplanar spacing is

As shown in Figure 14, and there is only one set of diffraction lattice of the α-phase antimony trioxide along the [111] direction, and there is no polycrystalline ring, indicating that the synthesized crystal quality is high and there are no other impurity phases, as shown in the figure. 15 shown. The nanosheet synthesized in Example 1 was characterized by an X-ray diffractometer (see FIG. 16). The characteristic peak signal of the spectrum was strong and there was no broadening phenomenon, indicating that the synthesized crystal was highly pure, single and high in quality. In addition, compared with the standard PDF card, it is found that the nanosheets only have (111) (222) (444) single characteristic peak signals, indicating that the growth direction of the synthesized α-phase antimony trioxide is along the (111) of _{Sb 2} O ₃ Surface growth. The particles synthesized in Example 3 were characterized by an X-ray diffractometer (see Figure 17). The characteristic peak signal of the spectrum is strong and can correspond to the PDF card one-to-one without other impurity peaks, indicating that the synthesis of α-phase antimony trioxide crystals is high-purity Single and high quality.

Characterization results of electronic band gap structure: The absorption spectrum of the nanosheet synthesized in Example 1 was measured by ultraviolet spectrophotometry, and after conversion into a Tauc curve, the optical band gap E _g ～5.6eV of the α-phase antimony trioxide was obtained (see figure) 21), to meet the second index of ultra-low dielectric constant materials.

Thermal stability test results: the samples synthesized in Example 1 were subjected to heat preservation at 400, 500, 550, and 600° C. for 2 hours, and then were naturally cooled to test Raman spectra to study their high-temperature thermal stability. It is found that the α-phase antimony trioxide can withstand a high temperature of 550°C, keep the morphology (see Figure 22) and chemical structure (see Figure 23) unchanged, and this temperature resistance can reach the index of ultra-low dielectric constant materials. , And better than the current mainstream pSiCOH low-dielectric constant materials.

Characterization results of dielectric properties: A commercial scanning microwave impedance microscope ScanWave ^TM 1.5 (PrimeNano) based on atomic force microscopy (Cypher S, Asylum Research, Oxford), a special sMIM probe (5-300N, PrimeNano), combined with COMSOL 5.4 software The established finite element simulation characterizes the dielectric constant of the nanosheets synthesized in Example 1. The test situation of the sample is shown in Figure 24. It can be seen that the scanning microwave impedance-reactance signal of the sample is darker than that of the substrate, and the scanning microwave impedance-reactance signal of the sample with different thickness has different contrast with the substrate. The thicker the sample The stronger the contrast; regardless of the thickness of the sample, the scanning microwave impedance-resistance signal does not exist or is so small that it is negligible. This shows that the sample only undergoes a simple dielectric reaction in this system, and there is no conductive reaction, and its dielectric constant is definitely lower than that of the mica substrate. The match between the results of the simulation analysis and the experimental data is shown in Figure 25. It can be seen that the dielectric constant of the α-phase antimony trioxide is between 1.8 and 2.5, reaching the first index of ultra-low dielectric constant materials. Theoretical calculation of dielectric constant results: using first-principles calculation software, apply an external electric field to the antimony trioxide film of different layers, and calculate the induced dipole moment by Berry phase theory to obtain different layers The average ion polarizability and average electron polarizability of each antimony hexaoxide cage are fitted to the relationship curve between the number of layers and the total average polarizability, and the value of the average total polarizability converging with the number of layers is substituted into it Clausius-Mossotti equation (Clausius-Mossotti equation), calculated the dielectric constant value of the final antimony trioxide single crystal. As shown in Figure 26, the dielectric constant of the α-phase antimony trioxide is 2.24, reaching the first index of ultra-low dielectric constant materials. Theoretical calculation of dielectric constant results in Peng,Jun; Pu,Weiwen; Lu,Shengnan; Yang,Xianzhong; Wu,Congcong; Wu,Nan; Sun,Zhaoru*; Wang,Hung-Ta*; Inorganic Low k Cage-molecular Crystals , Nano Letters, 2021, 21(1): 203-208. The text and supplementary parts.

Insulation characterization results: measured by self-assembled metal-insulator-metal (MIM) device (Figure 27) combined with semiconductor parameter analyzer (B1500A, Keysight) on manual probe station (S1160, Signatone) 1 Characterization of the dielectric constant of the synthesized nanosheets. The scanning electron microscope image of the actual MIM device is shown in Figure 28. The measured 6 representative "current density-voltage" curves are shown in Figure 29. Take the voltage value obtained through the intersection of the current density inverse epitaxial line and the x-axis after breakdown in the "current density-voltage" curve, and further normalize with the thickness of the nanosheet to obtain the breakdown strength E _B. The breakdown strength data obtained is summarized in Fig. 30, and the breakdown strength of the α-phase Sb ₂ O ₃ material is 1.4 ~ 2.5 MV/cm. This device verifies that the material of the present invention must have excellent insulation properties as a dielectric layer in a semiconductor integrated circuit device, and reaches the index four of an ultra-low dielectric constant material. The material appearance of the MIM device after breakdown is shown in Figure 31.

Mechanical characterization results: The α-phase Sb ₂ O ₃ was transferred from mica to a circular hole array device with a radius of 560 nm prepared in advance, and the nanosheets were mounted on the circular holes, as shown in Figure 32. Combined with atomic force microscope (Cypher S, Asylum Research, Oxford) and probe (ACTS160), nanoindentation experiment was performed to measure the two-dimensional effective elastic constant (k _2D ) of the film. The k _2D test results of 23 nanosheets are statistically shown in Figure 33, and the following formula is used to linearly fit them:

From the slope, the Young's modulus of α-phase Sb ₂ O _{3 is 15.2±0.8 GPa.} At the same time, using the finite element analysis simulation commercial software (name: multi-field physical simulation Comsol 5.3a software), the nanoindentation fracture experiment parameters (including Young's modulus, etc.) are substituted for fitting, and the fracture strain range is 6.1- 8.7%, the corresponding mechanical strength is 0.93-13.2GPa, see Figure 34. It is verified that the material has strong mechanical properties and reaches the index five of ultra-low dielectric constant materials.

The above examples are intended to illustrate the disclosed embodiments of the present invention, and should not be construed as limiting the present invention. In addition, the various modifications listed herein and the changes in the method and composition of the invention are obvious to those skilled in the art without departing from the scope and spirit of the invention. Although the present invention has been specifically described in conjunction with various specific preferred embodiments of the present invention, it should be understood that the present invention should not be limited to these specific embodiments. In fact, various modifications that are obvious to those skilled in the art to obtain the invention as described above should all be included in the scope of the present invention.

Claims (21)

A semiconductor integrated circuit, the interlayer or intermetal dielectric material of the semiconductor integrated circuit includes antimony trioxide material, and the antimony trioxide material is a molecular crystal made of Sb ₄ O ₆ cage-like molecules passing through van der Waals A two-dimensional or three-dimensional structure formed by force connection. 5. The semiconductor integrated circuit of claim 1, wherein the interlayer or intermetal dielectric material of the semiconductor integrated circuit further comprises a composite structure of antimony trioxide material and air voids. The semiconductor integrated circuit of claim 1 or 2, wherein the antimony trioxide material is α-phase antimony trioxide. The semiconductor integrated circuit of claim 1 or 2, further comprising any one or more of the following conditions: A1) The antimony trioxide material is a molecular crystal formed by self-assembly of _{Sb 4} O _{6 cage-like molecules;} A2) The antimony trioxide material is cubic crystal system, belonging to space group No. 227, and the symbol is expressed as

A3) of the antimony trioxide material

Interplanar spacing is

A4) The single crystal morphology of the antimony trioxide material is triangular nanosheets; A5) The single crystal morphology of the antimony trioxide material is octahedral crystal grains; A6) The dielectric constant of the antimony trioxide material is between 1.8 and 2.5; A7) The optical band gap of the antimony trioxide material is between 5.5 and 5.7 eV; A8) The breakdown field strength of the antimony trioxide material is between 1.4 and 2.5 MV/cm; A9) The antimony trioxide material can withstand a temperature greater than or equal to 550°C under normal pressure; A10) The Young's modulus of the antimony trioxide material is between 14.4 and 16 GPa; the mechanical strength of the antimony trioxide material is between 0.93 and 1.32 GPa. The semiconductor integrated circuit of claim 4, wherein the thickness of the triangular nanosheets is 0.6 nm to 2000 nm; and/or the particle size of the octahedral crystal grains is 0.2 μm to 10 μm. The semiconductor integrated circuit of claim 2, wherein the morphology of the composite structure of the antimony trioxide material and the air gap comprises a thin film formed by stacking the triangular nanosheets, wherein the thin film includes The stacking of triangular nanosheets results in naturally occurring air voids. The semiconductor integrated circuit of claim 2, wherein the morphology of the composite structure of the antimony trioxide material and the air gap comprises a thin film structure formed by stacking the octahedral crystal grains, wherein the thin film includes The naturally occurring air voids are caused by stacking octahedral grains. 7. The semiconductor integrated circuit of claim 6 or 7, wherein in the composite structure of the antimony trioxide material and the air gap, the volume ratio of the antimony trioxide material and the air gap is 5:1 to 100: 1 between. The application of antimony trioxide material as a dielectric material between semiconductor integrated circuit layers or between metals. The antimony trioxide material is a molecular crystal, which is a two-dimensional or two-dimensional connection formed _{by Sb 4} O _{6 cage molecules connected by van der Waals forces.} Three-dimensional structure. The application according to claim 9, wherein the antimony trioxide material is α-phase antimony trioxide. The application according to claim 9, characterized in that it further includes any one or more of the following conditions: B1) The antimony trioxide material is a molecular crystal formed by self-assembly of _{Sb 4} O _{6 cage-like molecules;} B2) The antimony trioxide material is cubic crystal system, belonging to space group No. 227, and the symbol is expressed as

B3) of the antimony trioxide material

Interplanar spacing is

B4) The single crystal morphology of the antimony trioxide material is triangular nanosheets; B5) The single crystal morphology of the antimony trioxide material is octahedral crystal grains; B6) The dielectric constant of the antimony trioxide material is between 1.8 and 2.5; B7) The optical band gap of the antimony trioxide material is between 5.5 and 5.7 eV; B8) The breakdown field strength of the antimony trioxide material is between 1.4 and 2.5 MV/cm; B9) The antimony trioxide material can withstand a temperature greater than or equal to 550°C under normal pressure; B10) The Young's modulus of the antimony trioxide material is between 14.4 and 16 GPa; the mechanical strength of the antimony trioxide material is between 0.93 and 1.32 GPa. The application according to claim 11, wherein the thickness of the triangular nanosheets is 0.6 nm to 2000 nm; and/or the particle size of the octahedral crystal grains is 0.2 μm to 10 μm. A method for preparing antimony trioxide material used in a semiconductor integrated circuit according to any one of claims 1 to 8, comprising: under vacuum conditions and an inert gas and/or oxygen atmosphere, antimony trioxide The powder and/or metal antimony powder is heated and volatilized and deposited on the substrate to obtain the antimony trioxide material. The preparation method of the antimony trioxide material according to claim 13, wherein the preparation method of the antimony trioxide material further comprises any one or more of the following technical features: C1) The substrate is selected from one or a combination of mica, silicon dioxide, graphene, and sapphire, preferably a mica substrate; C2) The vacuum conditions for the synthesis of the materials, that is, the pressure in the reaction is 3 to 500 Torr; C3) The inert gas is argon and/or nitrogen, preferably argon; C4) The synthesis reaction temperature is 320-700°C. Application of composite materials antimony trioxide and air voids between the metal layers or the semiconductor integrated circuit, the molecular crystal material is antimony trioxide, is formed by Van der Waals force connector Sb ₄ O ₆ from the cage-like molecules of two One-dimensional or three-dimensional structure. The application according to claim 15, wherein the antimony trioxide material is α-phase antimony trioxide. The application according to claim 15, characterized in that it further includes any one or more of the following conditions: D1) The antimony trioxide material is a molecular crystal self-assembled _{by Sb 4} O _{6 cage-like molecules;} D2) The antimony trioxide material is cubic crystal system, belonging to space group No. 227, and the symbol is expressed as

D3) of the antimony trioxide material

Interplanar spacing is

D4) The single crystal morphology of the antimony trioxide material is triangular nanosheets; D5) The single crystal morphology of the antimony trioxide material is octahedral crystal grains; D6) The dielectric constant of the antimony trioxide material is between 1.8 and 2.5; D7) The optical band gap of the antimony trioxide material is between 5.5 and 5.7 eV; D8) The breakdown field strength of the antimony trioxide material is between 1.4 and 2.5 MV/cm; D9) The antimony trioxide material can withstand a temperature greater than or equal to 550°C under normal pressure; D10) The Young's modulus of the antimony trioxide material is between 14.4 and 16 GPa; the mechanical strength of the antimony trioxide material is between 0.93 and 1.32 GPa. The application according to claim 17, wherein the thickness of the triangular nanosheets is 0.6 nm to 2000 nm; and/or the particle size of the octahedral crystal grains is 0.2 μm to 10 μm. The application according to claim 15, characterized in that the morphology of the composite structure of the antimony trioxide material and the air gap is a thin film composed of the triangular nanosheets, wherein the thin film includes Stacking triangular nanosheets results in naturally occurring air voids. The application according to claim 15, wherein the morphology of the composite structure of the antimony trioxide material and the air gap is a thin film structure formed by stacking octahedral crystal grains, wherein the thin film includes Stacking of octahedral grains results in naturally occurring air voids. The application according to claim 19 or 20, wherein the volume ratio of the antimony trioxide material and the air gap in the composite structure of the antimony trioxide material and the air gap is 5:1 to 100:1.

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