CN111048404B - Buffer layer structure and preparation method thereof - Google Patents

Abstract

A buffer layer structure, comprising: a substrate; an oxide buffer layer formed on the substrate; an iridium oxide layer formed on the oxide buffer layer; a platinum group metal seed layer formed on the oxide buffer layer On the iridium layer; the platinum group metal layer is formed on the platinum group metal seed crystal layer. Silicon carbide, silicon and sapphire are used as substrates, and the preparation process is integrated with the current semiconductor process. The substrate size has a wide range of choices, and the process stability is high, which can better meet the subsequent requirements; the existence of iridium oxide not only reduces the phase The degree of crystal mismatch of the adjacent thin film acts as a barrier layer to inhibit the solid-phase reaction of the platinum group metals and the oxide buffer layer, thereby effectively improving the quality of the platinum group metals; the in-situ preparation of the seed layer avoids the oxidation of oxides and the air. Oxygen, water vapor and other reactions keep the film surface in a good state, which reduces the difficulty of subsequent preparation of the platinum group metal layer.

Description

A kind of buffer layer structure and preparation method thereof

technical field

The invention relates to the technical fields of semiconductors, functional thin film materials and quantum spins, and in particular, to a buffer layer structure and a preparation method thereof.

Background technique

In recent years, wide bandgap semiconductor materials have become the strategic commanding heights of next-generation information technology, energy saving and emission reduction technology, and national defense and security technology in the field of high-power, high-frequency, and radiation-resistant microelectronics. Among them, diamond has broad development prospects and applications due to its wide band gap, high thermal conductivity, high breakdown electric field, and high carrier mobility. The preparation of devices puts forward higher requirements on the material preparation process. Since the commonly used substrate for homoepitaxy is high temperature and high pressure diamond, its epitaxial size is limited by the size of the substrate. Larger size diamond prepared by splicing method has grain boundary defects, and the cost is high. Therefore, the heteroepitaxial preparation of diamond has received extensive interest from domestic and foreign scientific research groups. In particular, some people have made great progress in the heteroepitaxial diamond on iridium (Ir). Iridium belongs to the noble metal of the platinum group. It is inappropriate to directly use iridium single crystal heteroepitaxy to prepare diamond from the perspective of economic and thermal expansion coefficient differences.

PGM thin films can be directly prepared on magnesium oxide (MgO), strontium titanate (STO), and iridium oxide stabilized zirconia (YSZ) (100) single crystals. However, this inevitably makes the size of the platinum group metal thin film subject to the development of the oxide crystal preparation process, and the price is relatively high. In contrast, monocrystalline silicon, silicon carbide and sapphire have a very complete industrial chain in terms of preparation and processing technology. Therefore, other equipment can be used to prepare the platinum group metal thin film after the oxide thin film on the silicon substrate. However, since the oxide film will react with water vapor or produce physical adsorption when exposed to the air, the surface state is changed, which increases the difficulty of the subsequent process. Therefore, by adopting the above method, high-quality platinum group metal thin films are often not obtained. In addition, the metal in the oxide layer often has the possibility of solid-phase reaction with the platinum group metal, which will lead to the deterioration of the quality of the platinum group metal layer.

SUMMARY OF THE INVENTION

In view of this, the main purpose of the present invention is to provide a buffer layer structure and a preparation method thereof, so as to partially solve at least one of the above technical problems.

In order to achieve the above object, as an aspect of the present invention, a buffer layer structure is provided, comprising:

substrate;

an oxide buffer layer formed on the substrate;

an iridium oxide layer formed on the oxide buffer layer;

a platinum group metal seed crystal layer formed on the iridium oxide layer;

A platinum group metal layer is formed on the platinum group metal seed layer.

Wherein, the material of the substrate is selected from silicon carbide, silicon and sapphire.

Wherein, the material of the oxide buffer layer is selected from at least one of yttria-stabilized zirconia, magnesium oxide and strontium titanate, and its thickness is 15-170 nm.

Wherein, the thickness of the iridium oxide layer is 5-200 nm;

The material of the platinum group metal seed layer is selected from at least one of platinum, palladium, osmium, iridium, ruthenium and rhodium.

Wherein, the material of the platinum group metal layer is selected from at least one of platinum, palladium, osmium, iridium, ruthenium and rhodium, and needs to be consistent with the material of the platinum group metal seed layer, and its thickness is 10-600 nm.

As another aspect of the present invention, a preparation method of a buffer layer structure is also provided, comprising the following steps:

preparing an oxide buffer layer on the substrate;

In-situ preparation of an iridium oxide layer on the oxide buffer layer;

In-situ preparation of a platinum group metal seed layer on the iridium oxide layer;

A platinum group metal layer is prepared on the platinum group metal seed layer.

Wherein, the step of preparing the oxide buffer layer on the substrate specifically includes: heating the substrate to 250-1200°C, and keeping the temperature for 10-60 minutes, wherein the heating rate is 1-20°C/min; the preparation temperature is set to 250-1200°C 1200°C, and prepare a thickness of 5-20nm under vacuum, and then inject oxygen to make the vacuum degree of the cavity ^10-5-100Torr , and continue to prepare to a thickness of 15-170nm; Press and hold for 0.5 to 12 hours; the method used in the process of preparing the oxide buffer layer is selected from pulsed laser deposition, magnetron sputtering, electron beam evaporation, ion beam assisted deposition, molecular beam epitaxy and metal organic chemical vapor deposition Related film preparation methods.

Wherein, the step of preparing the iridium oxide layer in situ on the oxide buffer layer specifically includes: the temperature of the substrate is lowered to 200° C., and then the temperature is raised to 250-1200° C., under the oxygen pressure of 10 ⁻⁵ to 100 Torr, the preparation of 5-200nm The iridium oxide film is kept for 0.5 to 12 hours under a high oxygen pressure of 1 to 200 Torr after the preparation.

Wherein, the step of preparing the PGM seed crystal layer in situ on the iridium oxide layer specifically includes: heating the substrate to 250-1200°C, and preparing the PGM under an oxygen or argon atmosphere of 10 ^-5 -100 Torr Metal seed layer.

Wherein, the step of preparing the platinum group metal layer on the platinum group metal seed layer specifically includes: preparing the platinum group metal layer with a background gas pressure of 10 ^-5 to 100 Torr, a preparation time of 2 to 10 hours, and a substrate temperature of 250 to 1200 Torr. ℃; the method used in the process of preparing the platinum group metal layer is selected from magnetron sputtering, electron beam evaporation, ion beam assisted deposition, molecular beam epitaxy and metal organic chemical vapor deposition related thin film preparation methods.

Based on the above technical solutions, the buffer layer structure and the preparation method thereof of the present invention have at least one of the following beneficial effects compared to the prior art:

1. Using silicon carbide, silicon and sapphire as the substrate, the preparation process is integrated with the current semiconductor process, the substrate size has a wide selection range, and the process stability is high, which can better meet the subsequent requirements;

2. The existence of iridium oxide not only reduces the crystal mismatch degree of adjacent thin films, but also acts as a barrier layer to inhibit the solid-phase reaction between platinum group metals and oxide buffer layers, thereby effectively improving the quality of platinum group metals;

3. The in-situ preparation of the seed layer avoids the reaction of oxides with oxygen and water vapor in the air, so that the film surface maintains a good state and reduces the difficulty of subsequent preparation of platinum group metal layers;

4. Iridium oxide/platinum group metal can be used as the back electrode of some devices, thereby reducing the complexity of the subsequent process of the device; and can reduce the signal transmission resistivity, and can improve the reliability of the device.

Description of drawings

Fig. 1 is the schematic diagram of the buffer layer structure of the present invention;

FIG. 2 is a flow chart of a method for preparing a buffer layer in an embodiment of the present invention.

In the above drawings, the meanings of the reference signs are as follows:

101, substrate; 102, oxide buffer layer; 103, iridium oxide layer;

104. PGM seed layer; 105, PGM layer.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

The invention discloses a buffer layer structure and a preparation method thereof, comprising: substrate/oxide buffer layer/iridium oxide layer/platinum group metal seed crystal layer/platinum group metal layer. By preparing the iridium oxide/platinum group metal seed crystal layer in situ, the repeatability of the platinum group metal preparation process is improved, and the prepared platinum group metal film has better quality. The platinum group metal film can be used as a buffer layer for epitaxial diamond, or as a back electrode for piezoelectric micromechanical systems, which can reduce the signal transmission resistivity and improve device reliability. At the same time, due to the wide application of platinum group metals in spin quantum devices, the structure can also be applied in this field.

Specifically, the present invention discloses a buffer layer structure, as shown in FIG. 1 , including:

substrate 101;

an oxide buffer layer 102 formed on the substrate 101;

an iridium oxide layer 103 formed on the oxide buffer layer 102;

a platinum group metal seed layer 104 formed on the iridium oxide layer 103;

The platinum group metal layer 105 is formed on the platinum group metal seed layer 104 .

Wherein, the material of the substrate 101 is selected from silicon carbide, silicon and sapphire.

Wherein, the material of the oxide buffer layer 101 is selected from at least one of yttria-stabilized zirconia, magnesium oxide and strontium titanate, and the thickness thereof is 15-170 nm.

Wherein, the thickness of the iridium oxide layer 103 is 5-200 nm;

The material of the platinum group metal seed layer 104 is selected from at least one of platinum, palladium, osmium, iridium, ruthenium and rhodium.

Wherein, the material of the platinum group metal layer 105 is selected from at least one of platinum, palladium, osmium, iridium, ruthenium and rhodium, and needs to be consistent with the material of the platinum group metal seed layer 104, and its thickness is 10~ 600nm.

As another aspect of the present invention, a method for preparing a buffer layer structure is also provided, as shown in FIG. 2 , comprising the following steps:

201: preparing an oxide buffer layer on a substrate;

202: in situ preparing an iridium oxide layer on the oxide buffer layer;

203: in situ preparing a platinum group metal seed layer on the iridium oxide layer;

204: Prepare a platinum group metal layer on the platinum group metal seed layer.

Wherein, the step of preparing the oxide buffer layer on the substrate specifically includes: heating the substrate to 250-1200°C, and keeping the temperature for 10-60 minutes, wherein the heating rate is 1-20°C/min; the preparation temperature is set to 250-1200°C 1200°C, and prepare a thickness of 5-20nm under vacuum, and then inject oxygen to make the vacuum degree of the cavity ^10-5-100Torr , and continue to prepare to a thickness of 15-170nm; Press and hold for 0.5 to 12 hours; the method used in the process of preparing the oxide buffer layer is selected from pulsed laser deposition, magnetron sputtering, electron beam evaporation, ion beam assisted deposition, molecular beam epitaxy and metal organic chemical vapor deposition Related film preparation methods.

Wherein, the step of preparing the iridium oxide layer in situ on the oxide buffer layer specifically includes: the temperature of the substrate is lowered to 200° C., and then the temperature is raised to 250-1200° C., under the oxygen pressure of 10 ⁻⁵ to 100 Torr, the preparation of 5-200nm The iridium oxide film is kept for 0.5 to 12 hours under a high oxygen pressure of 1 to 200 Torr after the preparation.

Wherein, the step of preparing the PGM seed crystal layer in situ on the iridium oxide layer specifically includes: heating the substrate to 250-1200°C, and preparing the PGM under an oxygen or argon atmosphere of 10 ^-5 -100 Torr Metal seed layer.

Wherein, the step of preparing the platinum group metal layer on the platinum group metal seed layer specifically includes: preparing the platinum group metal layer with a background gas pressure of 10 ^-5 to 100 Torr, a preparation time of 2 to 10 hours, and a substrate temperature of 250 to 1200 Torr. ℃; the method used in the process of preparing the platinum group metal layer is selected from magnetron sputtering, electron beam evaporation, ion beam assisted deposition, molecular beam epitaxy and metal organic chemical vapor deposition related thin film preparation methods.

Two preferred embodiments of the present invention are listed below.

Example 1

The method for preparing the YSZ/Ir thin film on a silicon substrate in this embodiment includes the following steps:

The YSZ layer is first prepared. Specifically, the silicon substrate was placed in a pulsed laser device, and the device was evacuated to a high vacuum. The temperature was raised to the preparation temperature at 5°C/min for 1 hour. After 5 minutes of preparation under background vacuum, 20 sccm of oxygen was introduced, and the preparation was continued for 45 minutes. After the preparation, the oxygen pressure was further increased, and the temperature was kept for 1 hour. And reduce to about 200 ℃ at 5 ℃/min, and cool with the furnace.

The Si/YSZ sample prepared above was put into a magnetron sputtering equipment, evacuated to high vacuum; heated to the preparation temperature, and kept for 1 hour. The Ir layer was prepared for about 2.5 hours by bubbling argon to keep the equipment at a constant pressure.

Example 2

The YSZ layer is first prepared. Specifically, the silicon substrate was placed in a pulsed laser device, and the device was evacuated to a high vacuum. The temperature was raised to a constant temperature at 5°C/min, and the temperature was maintained for 1 hour. After 5 minutes of preparation under background vacuum, 20 sccm of oxygen was introduced, and the preparation was continued for 45 minutes. After the preparation, the oxygen pressure was further increased, and the temperature was kept for 1 hour. And it is lowered to about 200°C at 5°C/min.

An iridium oxide layer is then prepared. The temperature was raised to a constant temperature at 5°C/min, and 20 sccm of oxygen was introduced to prepare an iridium oxide layer. It was then further elevated to hyperoxia and held for 1 hour. And it is lowered to about 200°C at 5°C/min.

Continue to prepare the iridium seed layer. The temperature was raised to a constant temperature at 5°C/min, and 20 sccm of argon was passed through to prepare an iridium seed layer. Incubate for one hour, and then reduce to about 200°C at 5°C/min, and cool with the furnace.

Put the silicon/yttrium oxide stabilized zirconia/iridium oxide/iridium seed layer sample prepared above into a magnetron sputtering device, pump to high vacuum; heat up to a constant temperature, and keep the temperature for 1 hour. Argon gas was introduced to keep the equipment under a certain pressure; the Ir layer was prepared under the radio frequency power supply for about 2.5 hours.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above-mentioned specific embodiments are only specific embodiments of the present invention, and are not intended to limit the present invention. Within the spirit and principle of the present invention, any modifications, equivalent replacements, improvements, etc. made should be included within the protection scope of the present invention.

Claims (10)

1. A buffer layer structure, comprising:

a substrate;

an oxide buffer layer formed over the substrate;

an iridium oxide layer formed on the oxide buffer layer;

a platinum group metal seed layer formed over the iridium oxide layer;

a platinum group metal layer formed on the platinum group metal seed layer;

the material of the platinum group metal layer is required to be the same as that of the platinum group metal seed crystal layer.

2. The buffer layer structure of claim 1, wherein the substrate is selected from the group consisting of silicon carbide, silicon, and sapphire.

3. The buffer layer structure of claim 1, wherein the oxide buffer layer is made of at least one material selected from the group consisting of yttria-stabilized zirconia, magnesia, and strontium titanate, and has a thickness of 15 to 170nm.

4. The buffer layer structure of claim 1, wherein the iridium oxide layer has a thickness of 5 to 200nm;

the platinum group metal seed layer is made of at least one material selected from the group consisting of platinum, palladium, osmium, iridium, ruthenium, and rhodium.

5. The buffer layer structure of claim 1, wherein the platinum group metal layer is made of at least one material selected from the group consisting of platinum, palladium, osmium, iridium, ruthenium, and rhodium, and has a thickness of 10 to 600nm.

6. A method of preparing a buffer layer structure according to any of claims 1 to 5, comprising the steps of:

preparing an oxide buffer layer on a substrate;

preparing an iridium oxide layer in situ on the oxide buffer layer;

preparing a platinum group metal seed crystal layer in situ on the iridium oxide layer;

a platinum group metal layer is prepared on the platinum group metal seed layer.

7. The method according to claim 6, wherein the step of preparing the oxide buffer layer on the substrate specifically comprises: heating the substrate to 250-1200 ℃, and keeping the temperature for 10-60 minutes, wherein the heating rate is 1-20 ℃/min; the preparation temperature is set to be 250-1200 ℃, the preparation thickness is 5-20 nm under vacuum, and then oxygen is introduced to ensure that the vacuum degree of the cavity is 10 ^-5 About 100Torr, and then continuously preparing the silicon carbide powder until the thickness is 15-170 nm; after the preparation is finished, the temperature is preserved for 0.5 to 12 hours under the high oxygen pressure of 1 to 200 Torr; the method used in the process of preparing the oxide buffer layer is selected from the group consisting of pulse laser deposition, magnetron sputtering, electron beam evaporation, ion beam assisted deposition, molecular beam epitaxy and metal organic chemical vapor deposition related film preparation methods.

8. The method of claim 6The preparation method is characterized in that the step of preparing the iridium oxide layer on the oxide buffer layer in situ specifically comprises the following steps: the temperature of the substrate is reduced to 200 ℃, and then is increased to 250-1200 ℃ at 10 DEG C ^-5 An iridium oxide thin film of 5 to 200nm is prepared under an oxygen pressure of 100Torr, and after the preparation is completed, the film is kept at a high oxygen pressure of 1 to 200Torr for 0.5 to 12 hours.

9. The preparation method according to claim 6, wherein the step of preparing the platinum group metal seed layer in situ on the iridium oxide layer specifically comprises: the substrate is heated to 250-1200 ℃ at 10 ^-5 The platinum group metal seed layer is prepared under an oxygen or argon atmosphere of about 100 Torr.

10. The method according to claim 6, wherein the step of preparing the platinum group metal layer on the platinum group metal seed layer specifically comprises: the background gas pressure for preparing the platinum group metal layer is 10 ^-5 About 100Torr, the preparation time is 2 to 10 hours, and the substrate temperature is 250 to 1200 ℃; the method used in the process of preparing the platinum group metal layer is selected from magnetron sputtering, electron beam evaporation, ion beam assisted deposition, molecular beam epitaxy and a preparation method of a film related to metal organic chemical vapor deposition.

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