JP5610391B2 - Metal silicide thin film manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a metal silicide thin film.

Metal silicide, for example, molybdenum silicide (MoSi ₂ , Mo ₂ Si ₃ etc.), tungsten silicide (WSi ₂ , W ₅ Si ₃ etc.), tantalum silicide (TaSi ₂ etc.), chromium silicide (CrSi ₂ etc.) or their The alloy exhibits electrical conductivity as high as that of a metal, and contains silicon, so that the alloy is suitable for use as an electrode material or a wiring material of a semiconductor device.

Among metal silicides, MoSi ₂ is known to have the highest electrical conductivity at room temperature, a melting point as high as about 2030 ° C., and high chemical stability (for example, Non-Patent Document 1). reference). In this case, like other metal silicides, MoSi ₂ has different resistivity and oxidation resistance depending on its crystal structure, and tetragonal crystals exhibit the best characteristics in practice.
Therefore, in application to semiconductor devices, it is important to form a tetragonal thin film of a metal silicide such as MoSi ₂ .

By the way, in the prior art, in order to produce a tetragonal thin film of a metal silicide such as MoSi ₂ , there is a method in which a substrate is heated at 1000 ° C. and a metal Mo and Si are formed by co-sputtering. However, in any of the methods, treatment at a high temperature close to 1000 ° C. was necessary. However, high-temperature treatment causes thermal interdiffusion and delamination due to shrinkage, which hinders complexation and integration with low-melting metals, glasses, and plastics with significantly different thermal expansion coefficients. Therefore, there is a problem that it is difficult to improve the performance and weight of the semiconductor device.

For this reason, a method for producing a tetragonal thin film of a metal silicide such as MoSi ₂ at a low temperature of about room temperature has been eagerly desired, but so far a tetragonal thin film has been successfully produced at room temperature. There were no examples.

Toru Mochizuki, “Molybdenum silicide as VLSI gate and wiring electrode”, Shizuoka University Graduate School of Electronic Science Research Report, March 15, 1986, Volume 7, p. 45-47

  Therefore, the subject of this invention is providing the method which can manufacture the tetragonal thin film of a metal silicide under normal temperature.

In order to solve the above-mentioned problems, the present invention uses an aerosol thin film deposition method (Aerosol Deposition Method, AD method), which is obtained by mixing fine particles of metal silicide with a carrier gas to form an aerosol in an atmosphere at room temperature under reduced pressure. , it injected into the substrate through the nozzle, by depositing the fine particles on the substrate by utilizing the impact consolidation phenomenon, to produce a thin film of the metal silicide maintaining the crystal structure of the fine particles of the metal silicide This is a method for producing a metal silicide thin film characterized in that.

In the above-described configuration, it is preferable to spray an aerosol obtained by mixing the metal silicide fine particles with a carrier gas onto the heated substrate.
As the metal silicide, it is preferable to use a silicide of molybdenum, tungsten, tantalum, chromium, or an alloy thereof, in particular, molybdenum silicide having a tetragonal crystal structure.
In the above structure, the carrier gas is preferably an inert gas, and the substrate is preferably an ITO substrate, a glass substrate, a silicon substrate, a sapphire substrate, or a plastic substrate.

According to the present invention, by using an aerosol thin film deposition method (AD method), a dense metal silicide thin film maintaining the crystal structure of the raw material metal silicide fine particles can be deposited on a substrate at room temperature. Thus, tetragonal metal silicide fine particles can be used as a raw material, and a metal silicide tetragonal thin film can be produced at room temperature. Therefore, a heat-sensitive material can be used as a substrate. Electronic components can be directly embedded in an electronic circuit board to realize small integration. In this case, when a tetragonal thin film of molybdenum silicide having a low resistivity is used as an electrode material or a wiring material of a Si-based semiconductor device, the contact resistance can be reduced and an ohmic contact can be easily realized.

Further, according to the present invention, a fine pattern thin film can be manufactured by adjusting the shape, dimensions, etc. of the nozzle, so that a maskless wiring pattern can be easily obtained at room temperature.
In addition, since the metal silicide thin film produced according to the present invention has a nano-order crystal structure and has high transparency, it can be applied to optical communication devices.

It is the schematic which shows the whole structure of an example of the aerosol film-forming apparatus suitable for implementing the metal silicide thin film manufacturing method by this invention. It is an X-ray diffraction diagram of MoSi ₂ thin film manufactured by the method of the present invention. And substrate temperature during MoSi ₂ thin film deposition is a graph showing the relationship between the obtained MoSi ₂ film resistivity. And the heat treatment temperature of the substrate after the MoSi ₂ thin film deposition is a graph showing the relationship between the obtained MoSi ₂ film resistivity.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
According to the present invention, a metal silicide thin film is manufactured using an aerosol thin film deposition method (Aerosol Deposition Method, AD method). In the AD method, a known aerosol film forming apparatus is used. FIG. 1 is a schematic diagram showing an overall configuration of an example of an aerosol film forming apparatus.

Referring to FIG. 1, the aerosol film forming apparatus includes a film forming chamber 1. An XY stage 2 for supporting and fixing the substrate 4 is attached to the inner surface of the upper wall of the film formation chamber 1, and aerosol is directed toward the substrate 4 fixed to the XY stage 2 inside the film formation chamber 1. A slit-like nozzle 3 for spraying is arranged. The nozzle 3 is fixed to the wall of the film forming chamber 1 in an upward state via suitable support means (not shown). The distance between the XY stage 2 and the nozzle 3 can be adjusted. Although not shown, the XY stage 2 is provided with a heating means for heating the substrate 4.
The inside of the film forming chamber 1 can be depressurized by a vacuum pump (mechanical booster pump 5 and rotary pump 6).

The aerosol film forming apparatus also includes an aerosolization chamber 7, a vibration table 8 on which the aerosolization chamber 7 is placed, a hoisting gas nozzle 9, and a pressure adjusting gas nozzle 10. One end of an aerosol transport pipe 11 is connected to the aerosolization chamber 7, and the other end of the aerosol transport pipe 11 is connected to the nozzle 3 of the film forming chamber 1.
A carrier gas is supplied to the aerosol chamber 7 through a gas supply pipe 13. The gas supply pipe 13 is branched into two on the way (13a, 13b). The branch pipes 13a and 13b are provided with mass flow meters 10a and 10b, respectively.

The hoisting gas nozzle 9 introduces a carrier gas supplied from the gas cylinder 12 through the gas supply pipes 13 and 13 a into the aerosol-generating chamber 7, thereby generating a cyclone flow. As a result, the fine particles 15 serving as a raw material disposed in the aerosol-generating chamber 7 are rolled up and dispersed to generate an aerosol.
The pressure adjusting gas nozzle 10 adjusts the gas pressure in the aerosolization chamber 7 by introducing the carrier gas supplied from the gas cylinder 12 through the gas supply pipes 13 and 13 b into the aerosolization chamber 7. Thereby, the pressure difference in the aerosolization chamber 7 and the film formation chamber 1 is adjusted.

  The fine particles 15 as a raw material are agitated and mixed with gas in the aerosolization chamber 7 to be aerosolized, and the fine particles 15 are aerosolized by a gas flow generated by a pressure difference between the aerosolization chamber 7 and the film forming chamber 1. The film is transported to the film forming chamber 1 through the transport pipe 11, accelerated through the slit-like nozzle 3, and sprayed toward the substrate 4. The fine particles transported by the gas are easily accelerated to several hundred m / sec by passing through the nozzle 3 having a minute opening of 1 mm or less. During the injection of the fine particles 15 onto the substrate 4, the substrate 4 is moved in the uniaxial direction at a predetermined timing by the XY stage 2, and a film is formed on the substrate 4.

  According to the present invention, the substrate is first cleaned. As the substrate, a known appropriate material such as an ITO substrate, a glass substrate, a silicon substrate, a sapphire substrate, or a plastic substrate can be used. The cleaning is performed using an appropriate cleaning liquid (for example, pure water, ethanol, acetone, etc.) in combination with the substrate to be used.

Next, the metal silicide fine particles (having a tetragonal crystal structure) are heated and dried using a hot plate or the like. The metal silicide used is not particularly limited, but is preferably a silicide of molybdenum, tungsten, tantalum, chromium, or an alloy thereof.
Then, the heat-dried fine particles of the metal silicide are put into the aerosol forming chamber 7 of the aerosol film forming apparatus. At this time, in order to promote aerosolization in the aerosol aerosolization chamber 7 when the aerosol film forming apparatus is operated, the same amount of glass beads as the fine particles of the heat-dried metal silicide are introduced into the aerosolization chamber. Is preferred.

A substrate 4 is attached to the XY stage 2 of the film forming chamber 1. The kind of the board | substrate 4 used is not specifically limited, For example, an ITO substrate, a glass substrate, a silicon substrate, a sapphire substrate, or a plastic substrate can be used. After the distance between the substrate 4 and the nozzle 3 and the gap between the slits of the nozzle 3 are adjusted, the pressure is reduced by the vacuum pumps 5 and 6 until the film forming chamber 1 reaches a predetermined pressure.
Further, the substrate 4 is heated by heating means (not shown) of the XY stage 2 . In addition, the vibration table 8 is activated to vibrate the aerosolization chamber 7.

  Thereafter, the carrier gas is supplied from the gas cylinder 12 to the aerosol-generating chamber 7 through the gas supply pipes 13, 13 a and 13, 13 b. At this time, the gas supply amount is controlled by the mass flow meters 14 a and 14 b, and a predetermined pressure difference is set between the aerosol forming chamber 7 and the film forming chamber 1.

  Thus, the fine particles 15 are agitated and mixed with the gas in the aerosol forming chamber 7 to be aerosolized, transported to the film forming chamber 1 through the aerosol transport pipe 11, accelerated through the nozzle 3, and sprayed toward the substrate 4. . Further, during the ejection of the fine particles 15 onto the substrate 4, the substrate 4 is moved in one axial direction by the XY stage 2 at a predetermined timing.

  At this time, the fine particles 15 colliding with the substrate 4 at a high speed adhere to the substrate 4 due to the impact solidification phenomenon at normal temperature, or the fine particles 15 adhere to each other, whereby the metal silicide is deposited on the substrate 4. A high density film is deposited. This metal silicide thin film maintains the crystal structure (tetragonal crystal) of the raw material fine particles 15.

[Experiment]
A thin film of MoSi ₂ was manufactured using the aerosol film forming apparatus shown in FIG.
As the raw material MoSi ₂ fine particles 15, Nihon Shin Metal's MoSi ₂ fine powder (MoSi ₂ -F, average particle size 2.0 to 5.0 μm) is used, and as the substrate 4, a sapphire substrate made by Water Works ( α-Al ₂ O ₃ single crystal, plane orientation C plane (0001), off orientation A axis 0.2 ± 0.05 °, thickness 430.00 ± 25.00 μm) (hereinafter referred to as “substrate No. 1”). 1 ”,“ Substrate No. 2 ”, and“ Substrate No. 3 ”).

Three substrates No. 1-No. 3 was washed with acetone and ethanol in that order for 5 minutes. First, substrate No. 1 was fixed to the XY stage 2 of the aerosol film forming apparatus, the distance between the nozzle 3 and the sapphire substrate 4 was set to 10 mm, and the slit gap of the nozzle 3 was set to 3 × 0.3 mm.
Further, 30 g of MoSi ₂ fine particles 15 were heated at 200 ° C. for 2 hours and dried using a hot plate. 30 g of the obtained MoSi ₂ fine particles were put into the aerosolization chamber 7 together with the same amount of glass beads (average particle diameter 1 mm), and the vibration table 8 was operated to vibrate the aerosolization chamber 7.

Thereafter, the film forming chamber 1 was decompressed to 10 Pa or less by the vacuum pumps 5 and 6. Subsequently, nitrogen gas was supplied from the gas cylinder 12 as a carrier gas, the gas flow rate of the mass flow meter 14a is 10L / min, and controls the gas supply amount so that the gas flow rate of the mass flow meter 14b is 1L / min, the MoSi ₂ particles Substrate No. 1 was sprayed. At the same time, the substrate No. 1 is reciprocated 20 times with a width of 10 mm in one axial direction. A 3 × 10 mm MoSi ₂ film was formed on 1.
In addition, MoSi ₂ fine particles were used for the substrate No. The temperature in the film forming chamber 1 during deposition on the substrate 1 was room temperature (25 ° C.).

Next, the substrate No. 2 is fixed to the XY stage 2 of the aerosol film forming apparatus. 2 except that MoSi ₂ fine particles were deposited while maintaining the temperature of 2 at 100 ° C. 1 under the same film formation conditions as in the case of No. 1. A MoSi ₂ film was formed on ₂ .
Next, the substrate No. 3 is fixed to the XY stage 2 of the aerosol film forming apparatus. 3 except that the MoSi ₂ fine particles were deposited while maintaining the temperature of 3 at 200 ° C. 1 under the same film formation conditions as in the case of No. 1. A MoSi ₂ film was formed on 3.

Each substrate No. having a MoSi ₂ thin film thus obtained was obtained. 1-No. 3 was X-ray diffracted. For comparison, X-ray diffraction was also performed on the raw material MoSi ₂ fine particles. Their X-ray diffraction patterns are shown in FIG. As shown in FIG. 1-No. In all cases, the X-ray diffraction pattern is the same as that of the raw material MoSi ₂ fine particles. Therefore, regardless of the substrate temperature during deposition of MoSi ₂ particles, MoSi ₂ thin film formed on the substrate was found to maintain the crystal structure of the MoSi ₂ particles of the raw material.

Next, each substrate No. 1-No. For No. ₃ , the resistivity of the MoSi ₂ thin film deposited thereon was measured by the four-probe method. The measurement results are shown in the graph of FIG. As can be seen from the graph of FIG. 3, the resistivity of the resulting MoSi ₂ thin film decreases exponentially as the substrate temperature during deposition of MoSi ₂ fine particles increases. Thus, according to the present invention, an extremely small resistivity can be realized at a temperature (about 200 ° C.) that is much lower than the substrate temperature (500 ° C. or higher) required for producing a MoSi ₂ thin film by the conventional sputtering method. Can do.

The heat treatment temperature of the substrate after the MoSi ₂ thin film deposition, in order to confirm whether affects the resistivity of the MoSi ₂ thin films obtained, the substrate No. Four of the same substrates as those of No. 1 were prepared. After film-forming MoSi ₂ under the same film-forming conditions as in No. 1, the film is heated in vacuum at 200 ° C., 400 ° C., 500 ° C., 600 ° C. for a predetermined time, and the resistivity of the MoSi ₂ thin film after the heat treatment is It was measured by the four probe method. The measurement results are shown in the graph of FIG. From the graph of FIG. 4, it was found that even when the substrate after the deposition of the MoSi ₂ thin film was heat-treated, the resistivity of the obtained MoSi ₂ thin film was hardly affected.

DESCRIPTION OF SYMBOLS 1 Deposition chamber 2 XY stage 3 Nozzle 4 Substrate 5 Mechanical booster pump 6 Rotary pump 7 Aerosolization chamber 8 Shaking table 9 Hoisting gas nozzle 10 Pressure adjustment gas nozzle 11 Aerosol transport pipe 12 Gas cylinders 13, 13a, 13b Gas supply pipes 14a, 14b Mass flow Meter 15 Fine particles used as raw material

Claims (6)

With an aerosol thin film deposition method, a material obtained by aerosolized mixed with a carrier gas fine particles of metal silicide, in an atmosphere of room temperature under reduced pressure, injected into the substrate through the nozzle, the fine particles using an impact consolidation phenomenon A metal silicide thin film manufacturing method characterized by manufacturing a thin film of the metal silicide maintaining the crystal structure of the metal silicide fine particles by adhering to the substrate. 2. The method for producing a metal silicide thin film according to claim 1, wherein the metal silicide fine particles mixed with a carrier gas are sprayed onto the heated substrate to be aerosolized.   3. The method of manufacturing a metal silicide thin film according to claim 1, wherein the metal silicide is a silicide of molybdenum, tungsten, tantalum, chromium, or an alloy thereof.   The method for producing a metal silicide thin film according to claim 1, wherein the metal silicide is molybdenum silicide having a tetragonal crystal structure.   The metal silicide thin film manufacturing method according to claim 1, wherein the carrier gas is an inert gas.   6. The method for producing a metal silicide thin film according to claim 1, wherein the substrate is an ITO substrate, a glass substrate, a silicon substrate, a sapphire substrate, or a plastic substrate.

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