Silicon carbide film with uniform resistivity and preparation method thereof

Abstract

The present application provides a silicon carbide film with uniform resistivity and a preparation method thereof, belonging to the field of chemical vapor deposition technology. The present invention uses methyltrichlorosilane as a precursor raw material and argon as a carrier gas, preheats the doping gas through a preheater and completely decomposes it into nitrogen atom units, enters the chemical vapor deposition chamber, and supplies nitrogen atoms with uniform concentration, thereby forming a silicon carbide film with uniform resistivity. The resistivity deviation of the silicon carbide film prepared by the method of the present invention meets the production requirements of most products for the resistivity deviation of the carbonization scale. Compared with the silicon carbide film prepared by using N-type doping gas that has not been preheated, the resistivity deviation is lower, which can improve product quality and provide production demand rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical vapor deposition (CVD), and in particular relates to a silicon carbide film with uniform resistivity and a preparation method thereof. Background Art

[0002] Silicon carbide material has excellent physical, chemical and electrical properties such as wide band gap, high critical breakdown electric field, high thermal conductivity, high carrier saturation drift velocity, high temperature stability, high corrosion resistance and radiation resistance. It is one of the most widely used materials in semiconductor materials.

[0003] As the withstand voltage performance of silicon carbide devices improves, the control of the resistivity uniformity of silicon carbide films becomes increasingly stringent. Existing methods generally use N-type dopants to adjust the resistivity of silicon carbide films by fine-tuning the amount of nitrogen input when depositing silicon carbide films. However, it is difficult to obtain a silicon carbide film with uniform resistivity by simply adjusting the nitrogen content. Therefore, it is particularly important to provide a method for preparing a silicon carbide film with uniform resistivity. Summary of the invention

[0004] In view of the above problems existing in the prior art, the first technical problem to be solved by the present invention is to provide a method for preparing a silicon carbide film with uniform resistivity; the second technical problem to be solved by the present invention is to provide a silicon carbide film with uniform resistivity prepared by the above method.

[0005] In a first aspect, the present application provides a method for preparing a silicon carbide film with uniform resistivity, comprising the following steps:

[0006] S1. Clean the substrate and place it in a chemical vapor deposition chamber;

[0007] S2, preheating the doped gas in a preheater, controlling the temperature in the preheater to be 500-1500° C., and the pressure in the preheater to be 1-1000 torr;

[0008] S3. Evacuate the chemical vapor deposition chamber. When the indoor temperature reaches a predetermined deposition temperature, introduce a mixture of methyltrichlorosilane gas, argon gas and preheated doping gas. Adjust the introduction temperature and doping concentration of the doping gas, and perform chemical deposition until a silicon carbide film with uniform resistivity is generated.

[0009] In a feasible embodiment, the substrate material can be any material that can be used as a substrate in the prior art, without special limitation, and can be specifically selected according to actual needs. For example, the substrate can be selected from one or more of single crystal silicon, polycrystalline silicon, silicon carbide, quartz, sapphire or glass.

[0010] In a feasible implementation, the pretreatment method for cleaning the substrate can be any one of the prior art methods without particular limitation, and can be specifically selected according to actual needs. For example, the substrate can be cleaned by an ultrasonic cleaner.

[0011] In a feasible implementation manner, the vacuum degree of the chemical vapor deposition chamber is 0.01 to 800 torr.

[0012] In a feasible implementation manner, the vacuum degree of the chemical vapor deposition chamber is 10 to 700 torr.

[0013] In a feasible implementation manner, the predetermined deposition temperature is 1000-1500°C.

[0014] In a feasible implementation manner, the predetermined deposition temperature is 1300°C.

[0015] In a feasible implementation, when the predetermined deposition temperature is lower than 1000° C., the activity of the reaction gas decreases; when the predetermined deposition temperature is higher than 1500° C., the activity of the reaction gas is too high, making it difficult to control the deposition rate and amount of silicon carbide.

[0016] In a feasible implementation manner, the present application uses methyltrichlorosilane as a precursor raw material to provide a carbon source and a silicon source.

[0017] In a feasible implementation manner, methyltrichlorosilane is liquid at normal temperature and pressure.

[0018] In a possible embodiment, methyltrichlorosilane is introduced into the vapor deposition chamber via a carrier gas in the form of bubbling or direct vaporization.

[0019] In a feasible implementation, a carrier gas is introduced into the methyltrichlorosilane liquid, and the methyltrichlorosilane gas is brought into the vapor deposition chamber in the form of bubbling.

[0020] In a feasible implementation, methyltrichlorosilane liquid may also be converted into methyltrichlorosilane vapor via a vaporizer and then brought into the vapor deposition chamber via a carrier gas.

[0021] In a feasible embodiment, the purity of the methyltrichlorosilane gas is ≥ 99%.

[0022] In one possible embodiment, argon is used as the carrier gas.

[0023] In a feasible implementation, the purity of the argon gas is above 99.999%.

[0024] In a feasible implementation manner, according to actual needs, other inert gases, such as helium and neon, may also be selected as carrier gases.

[0025] In a feasible implementation manner, the introduction temperature of the doping gas is consistent with a predetermined deposition temperature.

[0026] In a feasible implementation manner, the doping gas is an N-type doping gas.

[0027] In a feasible implementation manner, the N-type doping gas includes nitrogen and / or ammonia.

[0028] In a feasible implementation, nitrogen doping elements are introduced to replace carbon elements in the silicon carbide film, so that a specific N element concentration is doped in the silicon carbide film, and the obtained silicon carbide film has a lower resistivity.

[0029] In a feasible implementation manner, when the doping gas is preheated in a preheater, the atmosphere in the preheater is an inert gas, such as argon.

[0030] In a feasible implementation manner, the volume content of the doping gas in the mixed gas is greater than 0.01% and less than 30%.

[0031] In a feasible implementation manner, the volume content of the doping gas in the mixed gas is greater than 0.01% and less than or equal to 10%.

[0032] In a feasible implementation manner, the deposition rate of the silicon carbide film is 10-100 μm / h.

[0033] In a feasible implementation manner, the deposition rate of the silicon carbide film is 10-50 μm / h.

[0034] In a feasible implementation, excessive concentration of doped N element may cause surface defects of the silicon carbide film and generate huge silicon carbide grains.

[0035] In a second aspect, the present application provides a silicon carbide film with uniform resistivity prepared by the above method.

[0036] In a feasible implementation, the resistivity of the silicon carbide film is 0.001 to 50,000 Ω·cm.

[0037] In a feasible implementation, the resistivity deviation of the silicon carbide film is within a reference range of 1 to 25 Ω·cm.

[0038] In a feasible implementation, the resistivity deviation of the silicon carbide film is within ±10Ω·cm.

[0039] In a feasible implementation, the resistivity deviation of the silicon carbide film is within ±5Ω·cm.

[0040] In a feasible implementation manner, the thickness of the silicon carbide film is 1-1000 μm.

[0041] In a third aspect, a composite substrate comprising a silicon carbide film with uniform resistivity is also implicitly within the protection scope of the present application.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1) The present invention provides a method for preparing a silicon carbide film with uniform resistivity, by using methyltrichlorosilane as a precursor raw material and argon as a carrier gas, preheating the N-type doping gas in a preheater and completely decomposing it into nitrogen atoms, and then supplying nitrogen atoms with uniform concentration to a substrate after entering a chemical vapor deposition chamber in the form of nitrogen atoms, thereby generating a silicon carbide film with uniform resistivity.

[0044] 2) The resistivity deviation of the silicon carbide film prepared by the method of the present invention meets the production requirements of most products for the resistivity deviation of the carbonization scale. Compared with the silicon carbide film prepared by using N-type doping gas without preheating treatment, the resistivity deviation is lower, which can improve product quality and meet production demand rate. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0046] The "range" disclosed in this application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range.

[0047] Example 1

[0048] The substrate is cleaned and placed in a chemical vapor deposition chamber; the doping gas N2 is preheated in a preheater, the temperature in the preheater is 1300°C, and the pressure in the preheater is 350 torr;

[0049] The chemical vapor deposition chamber is evacuated to a vacuum degree of 350 torr. When the indoor temperature reaches 1300°C, a mixed gas of methyltrichlorosilane gas, argon gas and preheated N2 is introduced, wherein the volume content of N2 in the mixed gas is 5%. After deposition at a deposition rate of 30 μm / h, a silicon carbide film with uniform resistivity is obtained.

[0050] Example 2

[0051] The substrate is cleaned and placed in a chemical vapor deposition chamber; the doping gas N2 is preheated in a preheater, the temperature in the preheater is 1300°C, and the pressure in the preheater is 350 torr;

[0052] The chemical vapor deposition chamber is evacuated to a vacuum degree of 350 torr. When the indoor temperature reaches 1300°C, a mixed gas of methyltrichlorosilane gas, argon gas and preheated N2 is introduced, wherein the volume content of N2 in the mixed gas is 4.5%. After deposition at a deposition rate of 30 μm / h, a silicon carbide film with uniform resistivity is obtained.

[0053] Example 3

[0054] The substrate is cleaned and placed in a chemical vapor deposition chamber; the doping gas N2 is preheated in a preheater, the temperature in the preheater is 1300°C, and the pressure in the preheater is 350 torr;

[0055] The chemical vapor deposition chamber is evacuated to a vacuum degree of 350 torr. When the indoor temperature reaches 1300°C, a mixed gas of methyltrichlorosilane gas, argon gas and preheated N2 is introduced, wherein the volume content of N2 in the mixed gas is 10%. After deposition at a deposition rate of 30 μm / h, a silicon carbide film with uniform resistivity is obtained.

[0056] Example 4

[0057] The substrate is cleaned and placed in a chemical vapor deposition chamber; the doping gas NH3 is preheated in a preheater, the temperature in the preheater is 1300°C, and the pressure in the preheater is 350 torr;

[0058] The chemical vapor deposition chamber is evacuated to a vacuum degree of 350 torr. When the indoor temperature reaches 1300°C, a mixed gas of methyltrichlorosilane gas, argon gas and preheated NH3 is introduced, wherein the volume content of NH3 in the mixed gas is 5%. After deposition at a deposition rate of 30 μm / h, a silicon carbide film with uniform resistivity is obtained.

[0059] Example 5

[0060] The substrate is cleaned and placed in a chemical vapor deposition chamber; the doping gas N2 is preheated in a preheater, the temperature in the preheater is 1000°C, and the pressure in the preheater is 0.01 torr;

[0061] The chemical vapor deposition chamber is evacuated to a vacuum degree of 0.01 torr. When the indoor temperature reaches 1000°C, a mixed gas of methyltrichlorosilane gas, argon gas and preheated N2 is introduced, wherein the volume content of N2 in the mixed gas is 0.01%. After deposition at a deposition rate of 10μm / h, a silicon carbide film with uniform resistivity is obtained.

[0062] Example 6

[0063] The substrate is cleaned and placed in a chemical vapor deposition chamber; the doping gas N2 is preheated in a preheater, the temperature in the preheater is 1500°C, and the pressure in the preheater is 800 torr;

[0064] The chemical vapor deposition chamber is evacuated to a vacuum degree of 800 torr. When the chamber temperature reaches 1500°C, a mixed gas of methyltrichlorosilane gas, argon gas and preheated N2 is introduced, wherein the volume content of N2 in the mixed gas is 10%. After deposition at a deposition rate of 100 μm / h, a silicon carbide film with uniform resistivity is obtained.

[0065] Example 7

[0066] The substrate is cleaned and placed in a chemical vapor deposition chamber; the doping gas N2 is preheated in a preheater, the temperature in the preheater is 1300°C, and the pressure in the preheater is 10 torr;

[0067] The chemical vapor deposition chamber is evacuated to a vacuum degree of 10 torr. When the indoor temperature reaches 1300°C, a mixed gas of methyltrichlorosilane gas, argon gas and preheated N2 is introduced, wherein the volume content of N2 in the mixed gas is 10%. After deposition at a deposition rate of 10 μm / h, a silicon carbide film with uniform resistivity is obtained.

[0068] Example 8

[0069] The substrate is cleaned and placed in a chemical vapor deposition chamber; the doping gas N2 is preheated in a preheater, the temperature in the preheater is 1300°C, and the pressure in the preheater is 700 torr;

[0070] The chemical vapor deposition chamber is evacuated to a vacuum degree of 700 torr. When the chamber temperature reaches 1300°C, a mixed gas of methyltrichlorosilane gas, argon gas and preheated N2 is introduced, wherein the volume content of N2 in the mixed gas is 5%. After deposition at a deposition rate of 50 μm / h, a silicon carbide film with uniform resistivity is obtained.

[0071] Example 9

[0072] The substrate is cleaned and placed in a chemical vapor deposition chamber; the doping gas NH3 is preheated in a preheater, the temperature in the preheater is 500°C, and the pressure in the preheater is 1000 torr;

[0073] The chemical vapor deposition chamber is evacuated to a vacuum degree of 700 torr. When the chamber temperature reaches 1000°C, a mixed gas of methyltrichlorosilane gas, argon gas and preheated NH3 is introduced, wherein the volume content of NH3 in the mixed gas is 5%. After deposition at a deposition rate of 30 μm / h, a silicon carbide film with uniform resistivity is obtained.

[0074] Comparative Example 1

[0075] The substrate is cleaned and placed in a chemical vapor deposition chamber; the doping gas N2 is preheated in a preheater, the temperature in the preheater is 1300°C, and the pressure in the preheater is 350 torr;

[0076] The chemical vapor deposition chamber is evacuated to a vacuum degree of 350 torr. When the indoor temperature reaches 1300°C, a mixed gas of methyltrichlorosilane gas, argon gas and preheated N2 is introduced, wherein the volume content of N2 in the mixed gas is 0.01%. After deposition at a deposition rate of 30 μm / h, a silicon carbide film with uniform resistivity is obtained.

[0077] Comparative Example 2

[0078] The substrate is cleaned and placed in a chemical vapor deposition chamber; the doping gas NH3 is preheated in a preheater, the temperature in the preheater is 1300°C, and the pressure in the preheater is 350 torr;

[0079] The chemical vapor deposition chamber is evacuated to a vacuum degree of 700 torr. When the chamber temperature reaches 1300°C, a mixture of methyltrichlorosilane gas, argon gas and preheated N2 is introduced, wherein N2 accounts for 30% of the volume of the mixture. Deposition is carried out at a deposition rate of 50 μm / h to obtain a silicon carbide film with uniform resistivity.

[0080] Comparative Example 3

[0081] Clean the substrate and place it in a chemical vapor deposition chamber;

[0082] The chemical vapor deposition chamber is evacuated to a vacuum degree of 350 torr. When the chamber temperature reaches 1300°C, a mixed gas of methyltrichlorosilane gas, argon gas and N2 that has not been preheated is introduced, wherein the volume content of N2 in the mixed gas is 5%. After deposition at a deposition rate of 30 μm / h, a silicon carbide film with uniform resistivity is obtained.

[0083] The silicon carbide films prepared in Examples 1-4 and Comparative Examples 1-3 were tested, and the resistivity of the silicon carbide deposited with a thickness of 500 μm was measured using a four-point probe device (see Table 1).

[0084] Table 1

[0085]

[0086]

[0087] It can be seen from Table 1 that in ordinary doping, that is, when the doping gas is not preheated, when the dopant content is maintained at a certain level, the resistivity deviation of the obtained silicon carbide film is 0 to 30Ω·cm. Taking the most widely used product group as the target, it is found that the production demand for the resistivity deviation of silicon carbide films of general products is 1 to 25Ω·cm. Most silicon carbide films meet the product specifications, but some silicon carbide films do not meet the product specifications and are therefore considered to be defective products.

[0088] When the N-type doping gas is directly introduced into the chemical vapor deposition chamber without preheating treatment, the decomposition of the N-type doping gas and the participation of the N-type doping gas in the deposition proceed synchronously. During this period, the proportion of the decomposed N-type doping gas and the proportion of the undecomposed N-type doping gas continue to change. Therefore, the content of the activated N dopant reaching the substrate varies with the position, resulting in uneven resistivity of the deposited silicon carbide film.

[0089] Compared with Example 1 and Example 4 and Comparative Example 3, the resistivity deviation of the silicon carbide film formed by deposition after the doping gas is preheated is smaller than the resistivity deviation of the silicon carbide film formed by deposition without the doping gas being preheated, especially when the doping gas is N2, the effect is more obvious. The N-type doping gas is preheated by the preheater and completely decomposed into nitrogen atomic units, and after entering the chemical vapor deposition chamber in the form of nitrogen atoms, nitrogen atoms with uniform concentration are supplied to the substrate, thereby generating a silicon carbide film with uniform resistivity.

[0090] The present application is described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that, without departing from the spirit and scope of the present application, a variety of equivalent replacements, modifications or improvements can be made to the technical solution of the present application and its implementation methods, all of which fall within the scope of the present application. The scope of protection of the present application shall be subject to the attached claims.

Claims

1. A method for preparing a silicon carbide film with uniform resistivity, characterized in that: The following steps are involved: S1. Clean the substrate and place it in a chemical vapor deposition chamber; S2, preheating the doped gas in a preheater, controlling the temperature in the preheater to be 500-1500° C., and the pressure in the preheater to be 1-1000 torr; S3. The chemical vapor deposition chamber is evacuated. When the indoor temperature reaches a predetermined deposition temperature, a mixed gas of methyltrichlorosilane gas, argon gas and preheated doping gas is introduced, wherein the volume content of the doping gas in the mixed gas is greater than 0.01% and less than or equal to 10%. The introduction temperature and doping concentration of the doping gas are adjusted, and chemical deposition is performed to generate a silicon carbide film with uniform resistivity; wherein the doping gas is nitrogen gas, and the introduction temperature of the doping gas is 1000-1500°C. By introducing nitrogen doping elements, the nitrogen element replaces the carbon element in the silicon carbide film, so that the silicon carbide film is doped with a specific N element concentration, and the obtained silicon carbide film has a lower resistivity.

2. The method for preparing a silicon carbide film with uniform resistivity according to claim 1, characterized in that: The vacuum degree of the chemical vapor deposition chamber is 0.01 to 800 torr.

3. The method for preparing a silicon carbide film with uniform resistivity according to claim 1, characterized in that: The predetermined deposition temperature is 1000-1500°C.

4. A silicon carbide film with uniform resistivity prepared by the method according to any one of claims 1 to 3.

5. The silicon carbide film with uniform resistivity according to claim 4, characterized in that: The resistivity of the silicon carbide film is 0.001 to 50,000 Ω·cm.

6. A composite substrate comprising the silicon carbide film with uniform resistivity according to claim 5, characterized in that: The composite substrate comprises a substrate and a silicon carbide film with uniform resistivity composited on the surface of the substrate.

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