KR100697669B1 - MANUFACTURING METHOD OF LOW-k PLASMA POLYMERIZED THIN FILMS AND LOW-k THIN FILMS MANUFACTURED THEREFROM - Google Patents

Abstract

The present invention relates to a low dielectric plasma polymerized thin film manufacturing method and a low dielectric full plasma thin film formed using the same, and more particularly to the production of a low dielectric plasma polymer thin film using a plasma enhanced chemical vapor deposition (PECVD) method It is about a method.

The present invention comprises the steps of evaporating a precursor solution by evaporating a precursor containing decamesylcyclopentacyloxane and cyclohexane in a bubbler, discharging the evaporated precursor from the bubbler and introducing it into a reactor for plasma deposition, the reactor Depositing a plasma polymerized thin film on a substrate in the reactor using plasma.

Thus prepared thin film according to the present invention is thermally stable and is formed in a thin film structure having a very low dielectric constant is effective in producing a metal multilayer thin film.

Description

TECHNICAL FIELD OF THE INVENTION A method for producing a low dielectric plasma polymer thin film and a low dielectric thin film manufactured therefrom {MANUFACTURING METHOD OF LOW-k PLASMA POLYMERIZED THIN FILMS AND LOW-k THIN FILMS MANUFACTURED THEREFROM}

1 is a schematic diagram of a plasma enhanced chemical vapor deposition (CVD) apparatus used to produce a low dielectric thin film for a semiconductor device in accordance with the present invention.

Figure 2 is a graph showing the dielectric constant for the low-k dielectric thin film prepared according to an embodiment of the present invention and the thin film after heat treatment and plasma treatment.

Figure 3 is a graph showing the thickness change of the low-k dielectric thin film prepared according to the embodiment of the present invention and the thin film after heat treatment and plasma treatment for this.

Figure 4 is a graph showing the chemical structure obtained by Fourier infrared spectroscopy for the low-k dielectric thin film prepared according to the embodiment of the present invention and the thin film after heat treatment and plasma treatment.

5 is a graph measuring the strength and elastic modulus of the low-k dielectric thin film manufactured according to the embodiment of the present invention and the thin film after heat treatment and plasma treatment through nano-indentor measurement.

Figure 6 is a graph showing the leakage current density for the low dielectric thin film produced according to the embodiment of the present invention and the thin film after heat treatment and plasma treatment against the applied voltage.

* Explanation of symbols for main parts of drawings *

1: Substrate 10, 11: Carrier gas reservoir

20, 21: flow regulator 30, 31: bubbler

40: RF generator 50: reactor

51: substrate support 53: shower ring

The present invention relates to a low dielectric plasma polymerized thin film manufacturing method and a low dielectric full plasma thin film formed using the same, and more particularly to the production of a low dielectric plasma polymer thin film using a plasma enhanced chemical vapor deposition (PECVD) method It is about a method.

One of the major steps in modern semiconductor device fabrication is the formation of metal and dielectric thin films on substrates by chemical reaction of gases. This deposition process is called chemical vapor deposition or CVD. In a typical thermal CVD process, a reactive gas is provided to a substrate surface, where thermal induced chemical reactions occur to form a desired thin film. The high temperatures at which certain thermal CVD processes are performed may damage the structure of the device with the layer formed on the substrate. A preferred method of depositing metal and dielectric thin films at relatively low temperatures is the plasma enhanced CVD method (PECVD) disclosed in US Pat. No. 5,362,526 entitled "Plasma Enhanced CVD Process Using TEOS Deposition of Silicon Oxide". Was referenced.

Plasma enhanced CVD technology promotes excitation and / or dissociation of reactive gases by applying high frequency (RF) energy in the reaction zone, resulting in plasmas of highly reactive species. The high reactivity of the free species reduces the energy required for chemical reactions to occur, thus lowering the temperature required for such PECVD processes. The introduction of such devices and methods has significantly reduced the size of the structure of semiconductor devices.

In addition, recently, an interlayer insulating film used for metal wiring is formed of a material having a low dielectric constant ( k ≦ 2.4) in order to reduce the signal delay (RC delay) of a multilayer metal film used in an integrated circuit of an ultra high density (ULSI) semiconductor device. Research to do is actively performed. The low dielectric thin film may be formed of an inorganic material or an organic material, such as an oxide film doped with fluorine (SiO ₂ ) and an amorphous carbon (aC: F) doped with fluorine. Polymeric films with relatively low dielectric constant and excellent thermal stability are mainly used as organic materials.

Silicon dioxide (SiO ₂ ) or silicon oxyfluoride (SiOF), which has been mainly used as an interlayer insulating film, has a high capacitance and long resistance-current delay time in the manufacture of ultra-high density circuits of 0.5 μm or less. Due to problems such as RC delay time, researches to replace it with a new low dielectric material have been actively conducted, but no specific solution has been proposed.

Low dielectric materials that are currently considered as alternatives to SiO ₂ include BCB (benzocyclobutene), SILK (Dow Chemical), FLARE (fluorinated poly (arylene ether), mainly used for spin coating. Allied Signals), organic polymers such as polyimide, and the like Black Diamond (Applied Materials), Coral (Novellus) used for chemical vapor deposition (CVD) ), SiOF, alkyl-silanes and parylenes, and porous thin film materials such as xerogels or aerogels.

Here, most polymer thin films are formed by a method of chemically synthesizing a polymer, spin coating on a substrate, and then spin casting. The material having a low dielectric constant formed by this method is formed of a dielectric having a low dielectric constant because the thin film density decreases because pores of several nanometers (nm) are formed in the film. In general, the organic polymers deposited by spin coating have advantages of low dielectric constant and excellent planarization, but they are not suitable in terms of application due to poor thermal stability due to a lower heat limit temperature of less than 450 ° C. Since pores are large in size and because of this, they are not uniformly distributed in the film, there are various difficulties in manufacturing the device. In addition, the adhesion to the upper and lower wiring material is poor, high stress due to thermal curing peculiar to the organic polymer thin film, and the dielectric constant is changed due to the adsorption of ambient moisture, such as the reliability of the device is poor.

On the other hand, the inventors of the present invention have studied a low-k dielectric thin film manufacturing method having a significantly lower dielectric constant than the conventional to solve the above problems, plasma polymerized polymer deposited by PECVD using a cyclic precursor precursor In the case of thin films, not only the nanometer sized pores can be formed, but also the complex process of pre and post treatments generated by spin casting can be reduced, and the dielectric constant of materials can be improved by methods such as plasma treatment. Devised to have.

The technical problem to be achieved by the present invention is to provide a method for producing a plasma-polymerized low-k dielectric thin film and a treatment method capable of improving the dielectric constant.

In order to achieve the above object, the present invention uses a thin film deposited by PECVD method using decamesylcyclopentaxane and cyclohexane as precursors for semiconductor device thin films used as interlayer insulating films.

More specifically, the decamesylcyclopentacyloxane and cyclohexane in each of the foamers are evaporated to vaporize, the carrier gas is introduced into the foamer, and the decamesylcyclopentacyloxane and cyclohexane are bubbled together with the carrier gas, respectively. After discharged out and introduced into the plasma deposition reactor at the same time, by chemical vapor deposition using the plasma of the reactor to deposit a thin film on the substrate in the reactor, heat treatment and helium plasma treatment to produce a thin film.

Hereinafter, a method for manufacturing a low dielectric thin film for a semiconductor device according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings so that a person skilled in the art may easily perform the present invention.

1 illustrates a PECVD apparatus used to manufacture a low dielectric thin film for a semiconductor device according to an embodiment of the present invention. In the PECVD apparatus using the PECVD method, a thin film deposition process is performed through a process chamber including an upper chamber lid and a lower chamber body. Through the shower ring formed inside the chamber lid, the reaction gas is uniformly sprayed onto the substrate seated on the upper surface of the susceptor formed in the chamber body to deposit a thin film. The reaction gas is supplied by a lower electrode formed of a substrate support. The thin film deposition process is activated by being activated by radio frequency (RF) energy.

In the embodiment of the present invention, the thin film for semiconductor device is deposited by plasma enhanced chemical vapor deposition (PECVD) method using the precursor of decamesylcyclopentacyloxane and cyclohexane. As shown in Fig. 1, the embodiment of the present invention uses a capacitor type PECVD apparatus which is a kind of PECVD apparatus. However, in addition to the illustrated PECVD apparatus of FIG. 1, all other types of PECVD apparatus may be used.

First and second flow controllers 10 and 11 containing carrier gases such as He and Ar, and first and second flow regulators 20 and 21 for controlling the number of moles of gas passing therethrough; RF generators for generating plasma in the first and second bubblers 30 and 31, solid state or liquid precursors 30 and 31, the reactor 50 through which the reaction proceeds, and the reactor 50. generator 40). The carrier gas reservoirs 10 and 11, the flow regulators 20 and 21, the bubblers 30 and 31, and the reactor 50 are connected through a transportation pipe 60. The reactor 50 is provided with a substrate susceptor connected to the RF generator 40 to generate a plasma around the substrate and to place the substrate thereon. The shower ring 53 receives the RF power from the RF generator 40 and functions as an upper electrode. The shower ring 53 is made of ceramic to prevent leakage of the chamber lead and the insulating gas and the reactant gas. The made showerhead extension is located between the showerhead and the chamber lid. A thin film is formed on the substrate by supplying the energy required to excite the injected reaction gas by the RF power supply to plasma the reaction gas injected through the shower ring 53. In the reactor, a substrate support 51 on which the substrate 1 is mounted is provided on the upper surface. A heater (not shown) is embedded in the substrate pedestal 51 to raise the substrate 1 seated on the substrate pedestal 51 to a temperature suitable for deposition in the thin film deposition process. In addition, the substrate pedestal 51 is electrically grounded to function as an electrode. After the deposition reaction is completed, the exhaust system is provided under the chamber body so that the reaction gas remaining inside the process chamber is discharged to the outside.

According to the present invention, a method of depositing a thin film using a PECVD apparatus is as follows. First, the substrate 1 made of silicon (P ⁺⁺ -Si) implanted with boron having metal characteristics is washed with trichloroethylene, acetone, and methanol, and then a reactor ( 50 is placed on the substrate support 51. At this time, the basic pressure of the reactor 50 is kept low by 5 × 10 ^-6 Torr or less through the pumping of the turbo molecular pump 55.

The first and second foamers 30 and 31 contain liquid decamesylcyclopentaxyloxane and cyclohexane, which are used as precursors, and the first and second foamers 30 and 31, respectively, up to 75 ° C and 45 ° C. Heat to evaporate the precursor solution inside the bubbler. Since two types of precursors are used in this embodiment, two foamers 30 and 31 are used. The precursors decamesylcyclopentaxylzedine and cyclohexane may be contained in any foamer. That is, decamesylcyclopentaxyloxane is contained as a precursor in the first foamer 30 and cyclohexane is contained in the second foamer 31 as a precursor, or cyclohexane is contained in the first foamer 30 as a precursor. The second foamer 31 may contain decamesylcyclopentaxylane as a precursor. However, the heating temperature of each foamer should be adjusted according to the type of precursor contained in the foamer.

Each of the first and second carrier gas storage units 10 and 11 contains 99.999% of ultra high purity helium (He) gas, which is used as a carrier gas, by the first and second flow regulators 20 and 21. Flow through the delivery pipe (60). Carrier gas moving along the transport pipe 60 is introduced into the precursor solution of the bubbler (30, 31) through the bubbler inlet pipe to generate bubbles, load the gaseous precursor and back to the transport pipe 60 through the bubbler discharge pipe Enter

Carrier gas and evaporated precursors flowing through the bubbler 30 and 31 along the delivery pipe 60 are injected through the heading 53 of the reactor 50, at which time the power of the RF power source 40 is applied. As a result, the reaction gas injected through the shower ring 53 is converted into plasma. The plasmalized precursor injected through the shower ring 53 of the reactor 50 is deposited on the substrate 1 placed on the pedestal 51 to become a thin film. After the deposition reaction is completed, the remaining gas is discharged to the outside by the exhaust system provided at the bottom of the reactor. At this time, the He pressure of the reactor 50 is 6 × 10 ^-1 Torr, the temperature of the substrate 1 is 35 ℃. The temperature of the substrate is controlled using a heater embedded in the substrate pedestal. In addition, the power supplied to the RF generator is 15 W, resulting in a plasma frequency of about 13.56 MHz.

The thickness of the PPDMCPSO: CHex thin film thus deposited was measured to be 0.4 μm to 0.5 μm. Looking at the deposition process is estimated to occur in detail as follows. First, the mixed monomers delivered to the reactor 50 are activated or decomposed into reactive species by plasma and condensed on the substrate 1. Here, since the cross-linking between the molecules of decamesylcyclopentacyloxane and cyclohexane is easily performed, the PPDMCPSO: CHex thin film deposited under appropriate conditions may be used for the silicon oxide group and methyl group of decamesylcyclopentacyloxane. Because of the methyl group, cross-linking can be easily performed to improve thermal stability, and polymer polymerization of methyl group of decamesylcyclopentaxyloxane and cyclohexane also occurs well.

The substrate thus prepared was further subjected to plasma treatment (PT) or annealing. The heat treatment is a heat treatment of the PPDMCPSO: CHex thin film at 400 ℃ for 1 hour in a nitrogen atmosphere. Plasma treatment was performed on the thin film using helium at a pressure of 0.2 Torr and a 50 W R.F. Run for 15 minutes on power.

The effects of the plasma polymerized polymer thin film and the thin film heat-treated and He plasma treated, respectively, were confirmed through the following experiments. In the accompanying drawings, the symbols AS, AS + PT, Ann and Ann + PT represent the following.

AS: plasma deposited PPDMCPSO: CHex thin film

AS + PT: Plasma-treated PPDMCPSO: CHex thin film

Ann: Thin film heat-treated with plasma deposited PPDMCPSO: CHex thin film

Ann + PT: Plasma-treated and heat-treated PPDMCPSO: CHex thin film

2 shows relative dielectric constants for the plasma deposited PPDMCPSO: CHex thin film, the thin film subjected to heat treatment or plasma treatment, and the thin film subjected to both heat treatment and plasma treatment. The dielectric constant was measured by making an Al / PPDMCPSO: CHex / metallic-Si capacitor on a very low-resistance silicon substrate and applying a signal at a 1 MHz frequency. When the dielectric constant of the plasma-deposited PPDMCPSO: CHex thin film (AS) was measured for the helium plasma-treated thin film (AS + PT), the relative dielectric constant decreased from 2.76 to 2.65. + PT) was significantly reduced from 2.58 to 2.2 compared to the thin film (Ann) consisting only of heat treatment.

Figure 3 is a graph showing the thickness change of the thin film prepared according to the embodiment of the present invention for the heat treatment and plasma treatment, and shows the change in the thickness of the thin film by heat treatment and helium plasma treatment of the plasma deposited PPDMCPSO: CHex thin film, The thickness change was measured using a surface profilometer. The initial plasma deposited PPDMCPSO: CHex thin film (AS) was reduced by about 12% from 533nm to 472nm after heat treatment. However, the reduction in thickness of both films after plasma treatment was only less than 0.5%.

4 is a graph showing a chemical bonding structure of a thin film manufactured according to an embodiment of the present invention using Fourier infrared spectroscopy, in FIG. 4, the horizontal axis represents wavenumber (cm ⁻¹ ), and the vertical axis represents Indicate normalized absorbance.

4A shows waveforms occurring over the entire frequency range. According to FIG. 4A, both the PPDMCPSO: CHex thin film polymerized by the plasma enhanced CVD method using decamesylcyclopentacyloxane and a cyclohexane precursor, and the thin film heat-treated and plasma-treated are applied to each chemical structure over the entire frequency range. Stretching is shown to occur at the same vibrational position. This indicates that both the PPDMCPSO: CHex thin film and the heat treated and plasma treated thin film polymerized by the plasma enhanced CVD method using the decamesylcyclopentacyloxane and the cyclohexane precursor have the same bonding structure.

FIG. 4b shows the normalized absorbance for hydrocarbons corresponding to organic matter in the absorbance for the entire frequency range of FIG. 4a. As shown in FIG. 4B, a PPDMCPSO: CHex thin film (AS) polymerized by plasma enhanced CVD using a decamesylcyclopentaxylzedine and a cyclohexane precursor, and a thin film (AS + PT) plasma-treated with the thin film (AS) ), The absorbance was gradually decreased in the order of the thin film (Ann) heat-treated the thin film (AS) and the thin film (Ann + PT) in which both the heat treatment and the plasma treatment of the thin film (AS). Looking at the standardized change in absorbance for hydrocarbon (CH _x ) in detail, the methyl group (ethyl group) and ethyl group (ethyl group) is shown respectively, the ethyl group is reduced more than the methyl group. Since the methyl group is in the form of silicon-carbon which is a basic bond, it did not show much loss even after plasma treatment. The reason is that the ethyl group produced by the mixed-polymerized cyclohexane is bonded to labile species inside the thin film in the form of a polymer such as -ethyl-ethyl-ethyl-(-CH ₂ -CH ₂ -CH _2- ). This is because it is likely to sublimate to the outside after the treatment.

FIG. 4C shows the normalized absorbance of the silicon-related bond structure among the absorbances for the entire frequency range of FIG. 4A, including carbon-silicon oxide (C-SiO), oxygen-silicon oxide (O-SiO), and silicon For the chemical bond of -methyl (Si-CH ₃ ). The silicon-related bonding structure, which is the backbone of PPDMCPSO: CHex thin film (AS), does not show much change even after heat treatment and plasma treatment.

These phenomena suggest that the density of the initial plasma deposited thin film AS is higher than that of the heat treated thin film Ann in the PPDMCPSO: CHex thin film. Since the heat-treated PPDMCPSO: CHex thin film has a relatively low density, helium ions (He ⁺ ) activated during helium plasma treatment penetrate into the film to sublimate the ethyl group to the outside of the film. Plasma treatment also has the effect of removing silicon-hydrogen oxide (Si-OH) bonds in the thin film.

FIG. 5 shows the strength through nano-indentor of a PPDMCPSO: CHex thin film polymerized by a plasma enhanced CVD method using a decamesylcyclopentaxoxane and a cyclohexane precursor, and a thin film heat-treated and plasma-treated. (FIG. 5A) and elastic modulus (FIG. 5B) are shown. The heat treated PPDMCPSO: CHex thin film (Ann) showed no significant change in strength from 0.26 MPa to 0.23 MPa, but the modulus of elasticity was significantly decreased from 2.28 GPa to 1.25 GPa. In the initial plasma deposited thin film (AS), the strength and modulus of elasticity after He plasma treatment decreased rapidly from 0.79 MPa / 7.37 GPa to 0.48 MPa / 3.22 GPa, respectively.

6 is a graph showing the insulation of the PPDMCPSO: CHex thin film, the change in leakage current density with respect to the applied electric field per unit thickness was measured. Insulation was measured by making a capacitor of Al / PPDMCPSO: CHex / M-Si / Al structure on a silicon substrate. As shown in the graph, as the applied voltage increases from 1 V to 100 V, the initial plasma deposited PPDMCPSO: CHex thin film (AS) exhibits insulation characteristics of about 10 ^-7 A / cm, while the heat-treated (Ann) and plasma treated thin films (PT) showed an increasing characteristic from 10 ^-9 A / cm to 10 ^-8 A / cm. However, as shown in FIG. 6, the plasma-treated and heat-treated PPDMCPSO: CHex thin films (AS + PT, Ann, Ann + PT) have excellent insulation properties with values of 10 ⁻⁸ A / cm or less at an applied voltage of 100 V or less. .

As a result of these various reliability measurements, PPDMCPSO: CHex thin films polymerized by plasma enhanced CVD using decamesylcyclopentaxylzene and cyclohexane precursors are characterized in terms of dielectric properties, film thickness variability, chemical bond structure variability, strength, elastic modulus and dielectric properties. It has been shown to have excellent properties.

What has been described above has described one embodiment according to the present invention, and the present invention is not limited to the above-described embodiment, and as claimed in the following claims, without departing from the gist of the present invention, the field to which the present invention pertains. It will be said that the scope of the present invention to the extent that those skilled in the art can change.

The present invention has a low dielectric thin film having a very low dielectric constant compared with the prior art when manufacturing a plasma polymerized polymer thin film deposited by PECVD using a cyclic precursor, and the thin film manufactured therefrom is less than nanometer size Not only can it form voids, but it also has the effect of reducing the complicated process of pre- and post-treatment in spin casting. In addition, it has the effect of improving the dielectric constant of the material by a method such as plasma treatment or heat treatment.

Claims (12)

A method for producing a low dielectric plasma polymer thin film, wherein the plasma polymerized thin film is deposited on a substrate by using a decamethylcyclopentaxoxane and a cyclohexane precursor by plasma enhanced CVD. In the method of manufacturing a low dielectric plasma polymer thin film, a low dielectric plasma polymer thin film which is subjected to heat treatment after depositing a plasma polymerized thin film using a decamesylcyclopentaxyloxane and a cyclohexane precursor by plasma enhanced CVD. Manufacturing method. In the method of manufacturing a low dielectric plasma polymer thin film, a low dielectric plasma polymer which is subjected to plasma treatment by depositing a plasma polymerized thin film on a substrate by using a decamethylcyclopentaxoxane and a cyclohexane precursor by plasma enhanced CVD. Thin film manufacturing method. In the method of manufacturing a low dielectric plasma polymer thin film, a low dielectric material in which a plasma polymerized thin film is deposited on a substrate by using a decamethylcyclopentaxoxane and a cyclohexane precursor by plasma enhanced CVD, and then subjected to heat treatment and plasma treatment. Plasma polymer thin film manufacturing method. A low dielectric plasma polymer thin film prepared according to the manufacturing method according to any one of claims 1 to 5. Evaporating the precursor solution by evaporating a precursor comprising decamesylcyclopentacyloxane and cyclohexane in a bubbler; Discharging the evaporated precursor from the bubbler and introducing the vaporized precursor into a plasma deposition reactor; Depositing a plasma polymerized thin film on a substrate in the reactor using the plasma of the reactor. 7. The method of claim 6, further comprising a heat treatment step. 8. The method of claim 7, further comprising a plasma step. 7. The method of claim 6, further comprising a plasma step. 10. The carrier gas pressure according to any one of claims 6 to 9, wherein the carrier gas pressure of the reactor is 6 × 10 ⁻¹ Torr, the substrate temperature is 35 ° C., the power supplied to the reactor is 15 W, and the plasma produced therefrom. And the frequency is 13.56 MHz. The method of claim 7, wherein the heat treatment is performed at 400 ° C. for 1 hour in a nitrogen atmosphere. 10. The method of any one of claims 7 to 9, wherein the plasma treatment is performed on a thin film using helium at a pressure of 0.2 Torr and a 50 W R.F. 15. A method of making a low dielectric plasma polymer thin film, characterized in that it runs for 15 minutes at power.

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