CN104120403B - A kind of silicon nitride film material and preparation method thereof - Google Patents

Abstract

The invention provides a kind of silicon-nitrogen compound membrane material and preparation method thereof: be placed in by substrate in high-density plasma reinforced chemical vapor deposition apparatus cavity, be passed through NH₃Gas and SiH₄Gas, as reacting gas, is passed through argon as carrier and protective gas, carries out vapour deposition, it is thus achieved that silicon nitride film material；Wherein, the operating temperature controlling high-density plasma reinforced chemical vapor deposition apparatus cavity is 50～80 DEG C, and operating pressure is 3～5Pa, and power is 390～460W；Wherein, the time of described vapour deposition is 5～7min；Described SiH₄Gas and NH₃The volume ratio of gas is 14～18, SiH₄Gas is 0.5～5 with the volume ratio of argon.The thickness of the silicon-nitrogen compound membrane material that the present invention prepares on four inches of silicon substrates is 107 110nm, and thin film inhomogeneities is less than 1.0%.

Description

A kind of silicon nitride film material and preparation method thereof

technical field

The invention belongs to the technical fields of optics, semiconductor and microelectronic devices, and in particular relates to a 100nm silicon nitride film material. The film material has good uniformity, a thickness of about 100nm, good insulation, stability and Mechanical properties, it can be used as an insulating layer, protective film or optical film, and is widely used in the fields of semiconductors, microwaves, optoelectronics and optical devices.

Background technique

Thin film is a special form of matter. Because of its small size in the specific direction of thickness, it is only a microscopically measurable amount, and the continuity of matter is interrupted due to the existence of surface and interface in the direction of thickness. This makes thin film materials have unique properties different from bulk materials.

Optical thin films are composed of thin layered media, a type of optical dielectric material that propagates light beams through the interface, and are widely used in the fields of optics and optoelectronics technology to manufacture various optical instruments. Optical thin film technology has formed a complete system in terms of theory, design, calculation and technology. Some functional thin films with new microstructures have been continuously developed. The successive appearance of these functional thin films has made optical thin film technology widely penetrate into various emerging sciences. in the field of research. Silicon nitride thin film is an important fine ceramic thin film material, which has good insulation properties, optical properties, passivation properties, stability and mechanical properties, and has broad application prospects in the fields of microelectronics, optoelectronics and material surface modification. .

As the application of thin films becomes more and more extensive, the preparation technology of thin films has gradually become an important means in the processing technology of high-tech products. There are many methods for preparing thin films, such as vapor phase growth, liquid phase growth (or gas, liquid phase epitaxy), oxidation, diffusion and coating, electroplating, etc., and each film production method can be divided into two types: for several methods. The plasma chemical vapor deposition (PECVD) method provides the possibility of preparing various thin films on different substrates due to its flexibility, low deposition temperature and good repeatability, and has become one of the most commonly used methods for preparing silicon nitride thin films. .

The uniformity of the 100nm film is the key problem and challenge that needs to be solved first in the thin film preparation process. The uniformity of the film thickness reflects the change of the thickness of the film deposited on the substrate to be plated according to the position of the substrate in the vacuum chamber. The uniformity of film thickness includes two aspects: ①The films deposited on different substrate positions in the same group of plating process have similar film thickness distribution; ②Each film obtained has only a certain range of film thickness error distribution. Aspect ① of film thickness uniformity ensures industrialized coating efficiency, and aspect ② ensures the performance of each finished product. Therefore, the film thickness uniformity is an important index to measure the performance of the coating device and the quality of the film, and directly affects the reliability, stability, and product consistency of the coating device. It has a great influence on the yield rate of the production of optical, photoelectric and other devices.

Therefore, there is a need in the art to find a silicon nitride film material with good uniformity.

Contents of the invention

In order to overcome the defect of relatively large inhomogeneity of the silicon nitride film in the prior art, one of the objects of the present invention is to provide a silicon nitride film material with a thickness of 107-110 nm; and Film non-uniformity less than 1.0% within four inches of substrate;

Wherein, the calculation method of the inhomogeneity is: film inhomogeneity=(maximum value-minimum value)/(average value×2)×100%, within the scope of the four-inch substrate, the measured number of different points is not less than 17 .

Wherein, the maximum value is the maximum value of the test point thickness of the silicon nitride film material; the minimum value is the minimum value of the test point thickness of the silicon nitride film material; the average value is the average value of the test point thickness of the silicon nitride film material, and the calculation The formula is: average value = sum of test point thickness/number of test points.

Preferably, the composition of the silicon nitride film material is SiN _x , where 1≤x≤2.

The film nonuniformity of the silicon nitride film material provided by the invention is lower than 1.0%.

The second object of the present invention is to provide a method for preparing the silicon nitride film material described in the first object, the method is:

Put the substrate in the cavity of high-density plasma enhanced chemical vapor deposition equipment, pass NH ₃ gas and SiH ₄ gas as reaction gas, and pass argon gas as carrier and protective gas for vapor deposition to obtain silicon nitride film Material;

Among them, the working temperature of the high-density plasma-enhanced chemical vapor deposition equipment cavity is controlled to be 50-80°C, the working pressure is 3-5Pa, and the power is 390-460W;

Wherein, the vapor deposition time is 5-7 minutes; the volume ratio of SiH ₄ gas to NH ₃ gas is 14-18, and the volume ratio of SiH ₄ gas to argon gas is 0.5-5.

For the method of preparing silicon nitride film materials using high-density plasma-enhanced chemical vapor deposition equipment, there are many operating conditions, including temperature, pressure, power, time, gas ratio, etc., and there is a close relationship between them. is not an independent single variable, so how to find a suitable operating condition is difficult for those skilled in the art.

In the operating conditions of using high-density plasma-enhanced chemical vapor deposition equipment to prepare silicon nitride film materials, the working temperature of the cavity of the high-density plasma-enhanced chemical vapor deposition equipment is set at 50-80°C, and the working pressure is set at 3-80°C. 5Pa, the power is set to 390-460W; and the time of vapor deposition is controlled to be 5-7min; the volume ratio of SiH ₄ gas to NH ₃ gas is controlled to be 14-18, and the silicon nitride with a thickness of about 100nm is controlled. The purpose of film material film non-uniformity is less than 1.0%.

In the operating conditions for preparing silicon nitride film materials using high-density plasma-enhanced chemical vapor deposition equipment described in the present invention, the defined values include any values within the stated range, for example, high-density plasma-enhanced chemical vapor deposition The working temperature of the equipment cavity can be 52°C, 67°C, 78°C, 79°C, etc., the working pressure can be 3.2Pa, 3.8Pa, 4.1Pa, 4.3Pa, 4.7Pa, 4.9Pa, etc., and the power can be 390W, 419W , 423W, 435W, 447W, 453W, 460W, etc., the vapor deposition time can be 5.3min, 5.5min, 5.8min, 6.2min, 6.6min, etc., and the volume ratio of SiH ₄ gas to NH ₃ gas can be 14.4 , 15.3, 15.8, 16.5, 17, etc.

The substrate of the present invention is any one of P-type doped single crystal silicon, N-type doped single crystal silicon or metal; or prepare a layer of uniform metal or non-metal thin film on the above-mentioned substrate as the experiment. substrate.

Preferably, the P-type doped single crystal silicon or N-type doped single crystal silicon substrate is pretreated as follows: soak in HF acid, wash with deionized water, and then dry;

Preferably, the mass concentration of the HF acid is 2-10%, such as 3%, 5%, 7%, 8.3%, 9%, etc., more preferably 5%;

Preferably, the soaking time with HF acid is 0.5-10 min, such as 1 min, 1.4 min, 3 min, 5 min, 7 min, 8.4 min, 9 min, etc., more preferably 3 min.

Preferably, the metal substrate is pretreated as follows: ultrasonic cleaning with acetone and isopropyl alcohol, and then drying; the ultrasonic time is preferably 5 minutes.

As most preferably, in the preparation method of the silicon nitride film material of the present invention, the working temperature of the cavity of the high-density plasma enhanced chemical vapor deposition equipment is controlled to be 55°C, the working pressure is 4Pa, and the power is 410W; the vapor deposition The time is 5-7 minutes; the volume ratio of the SiH ₄ gas to the NH ₃ gas is 16.5, and the volume ratio of the SiH ₄ gas to the argon gas is 1.0.

As a preferred technical solution, the method for preparing a silicon nitride film material with good uniformity and a thickness of about 100 nm in the present invention includes the following steps:

(1) Place the substrate in the cavity of the high-density plasma enhanced chemical vapor deposition equipment, evacuate the vacuum so that the vacuum degree of the back and the bottom is 1×10 ^-4 ~ 1×10 ^-6 Pa, and heat the substrate to 50~60°C ;

(2) According to the volume ratio of 1: (14 ~ 18), NH ₃ gas and SiH ₄ are introduced as reaction gas, and argon gas is introduced as carrier gas and protective gas, and the working pressure is adjusted to 3 ~ 5Pa, and the power is 390 ~ 460W , carry out chemical vapor deposition for 5-7 minutes;

(3) Under the atmosphere of protective gas, the temperature is lowered to room temperature to obtain the silicon nitride film material described in one of the objectives.

Preferably, the protective gas described in step 3) is an inert gas; the inert gas is preferably argon.

The third object of the present invention is to provide the use of the silicon nitride film material described in the first object, which is used as an insulating layer, protective film or optical film, and is applied to semiconductors, microwaves, optoelectronics and optical devices and other fields.

Compared with prior art, the present invention has following characteristics:

(1) The thickness of the silicon nitride film material provided by the present invention is about 100nm, and has good uniformity, within the scope of four inches of substrates, the film nonuniformity is lower than 1.0%; Compared with existing magnetron sputtering method and The uniformity of the silicon nitride film material obtained by the electron beam evaporation method is significantly improved;

(2) The substrate used in the present invention adopts P (or N) type doped single crystal silicon, metal or above-mentioned substrate to prepare one deck metal or non-metal film, can prepare at different material interface and have good uniformity, thickness is Silicon nitride film material of about 100nm;

(3) The preparation process of the silicon compound thin film material with good uniformity of 100 nanometers provided by the present invention is simple and easy, and has great application potential.

Description of drawings

FIG. 1 is a distribution diagram of test points for film thickness characterization in Example 1 of the present invention.

detailed description

In order to facilitate understanding of the present invention, the present invention enumerates the following examples. It should be clear to those skilled in the art that the embodiments are only for helping to understand the present invention, and should not be regarded as specific limitations on the present invention.

Example 1

A silicon nitride film material is prepared by the following method:

(1) Use polished N-type (100) doped single crystal silicon as the substrate, and perform the following pretreatment: first soak the substrate with 5wt% HF acid for 3 minutes, then clean it with deionized water, and dry it at last its surface;

(2) Put the pretreated substrate obtained in step (1) into the chamber of high-density plasma-enhanced chemical vapor deposition equipment, and evacuate the deposition chamber so that the vacuum degree of the background is 1×10 ^-5 Pa or so, and heat the substrate to 55°C;

(3) With the SiH ₄ gas, NH ₃ gas and Ar ₂ gas with a purity greater than 99.99% as the gas source; wherein, SiH ₄ gas, NH ₃ gas are the reaction gases, Ar ₂ gas is the carrier gas and protective gas, and the supplied The flow rates of Ar ₂ gas, NH ₃ gas and SiH ₄ gas are: 140sccm, 8.8sccm, 145sccm respectively; the working pressure of the deposition chamber is controlled to 4Pa, the power is 410W, and the chemical vapor deposition is carried out for 6.2min;

(4) under an Ar ₂ gas atmosphere, cool down to room temperature to obtain a Si ₃ N ₄ thin film with good uniformity and a thickness of about 100 nm;

Performance Characterization:

The obtained Si ₃ N ₄ film material is carried out spectroscopic ellipsometer (equipment model is SE 850) test, test condition is: room temperature, 200～930nm wavelength range scanning, choose 17 test points, the distribution of described 17 test points is 1 center point, 8 circle points with a radius of r, and 8 circle points with a radius of 2r, and the circle points are evenly distributed on the circle where the value of r is less than 1 of the shortest side length of the substrate /4; the test results are shown in Figure 1, and the non-uniformity is calculated to be 0.92%.

Example 2

A silicon nitride film material is prepared by the following method:

(1) Prepare a 200nm thick Ti film on the polished P-type (100) doped single crystal silicon wafer, and use this as the substrate, and carry out the following pretreatment: first use acetone and isopropanol to sonicate for 5min respectively, Then wash with deionized water, and finally dry the surface;

(2) Put the pretreated substrate obtained in step (1) into the chamber of high-density plasma-enhanced chemical vapor deposition equipment, and evacuate the deposition chamber so that the vacuum degree of the background is 1×10 ^-5 Pa or so, and heat the substrate to 70°C;

(3) With the SiH ₄ gas, NH ₃ gas and Ar ₂ gas with a purity greater than 99.99% as the gas source; wherein, SiH ₄ gas, NH ₃ gas are the reaction gases, Ar ₂ gas is the carrier gas and protective gas, and the supplied The flow rates of Ar ₂ gas, NH ₃ gas and SiH ₄ gas are: 145sccm, 8.8sccm, 123sccm respectively; the working pressure of the deposition chamber is controlled to 3Pa, the power is 450W, and the chemical vapor deposition is carried out for 5.2min;

(4) under an Ar ₂ gas atmosphere, cool down to room temperature to obtain a Si ₃ N ₄ thin film with good uniformity and a thickness of about 100 nm;

The obtained Si ₃ N ₄ film material was tested by a spectroscopic ellipsometer (equipment model: SE 850), and the test method was the same as the performance characterization method of Example 1; the non-uniformity was calculated to be 0.94%.

Example 3

A silicon nitride film material is prepared by the following method:

(1) Make the substrate with polished Ti metal, and carry out the following pretreatment: first, the substrate is ultrasonicated for 5 minutes with acetone and isopropanol, then cleaned with deionized water, and finally the surface is dried;

(2) Put the pretreated substrate obtained in step (1) into the chamber of high-density plasma-enhanced chemical vapor deposition equipment, and evacuate the deposition chamber so that the vacuum degree of the background is 7×10 ^-6 Pa or so, and heat the substrate to 80°C;

(3) With the SiH ₄ gas, NH ₃ gas and Ar ₂ gas with a purity greater than 99.99% as the gas source; wherein, SiH ₄ gas, NH ₃ gas are the reaction gases, Ar ₂ gas is the carrier gas and protective gas, and the supplied The flow rates of Ar ₂ gas, NH ₃ gas and SiH ₄ gas are: 130sccm, 8.8sccm, 158sccm respectively; the working pressure of the deposition chamber is controlled at 5Pa, the power is 460W, and the chemical vapor deposition is carried out for 6.8min;

(4) under an Ar ₂ gas atmosphere, cool down to room temperature to obtain a Si ₃ N ₄ thin film with good uniformity and a thickness of about 100 nm;

The obtained Si ₃ N ₄ film material was tested by a spectroscopic ellipsometer (equipment model: SE 850), and the test method was the same as the performance characterization method of Example 1; the non-uniformity was calculated to be 0.89%.

The applicant declares that the present invention illustrates the detailed methods of the present invention through the above-mentioned examples, but the present invention is not limited to the above-mentioned detailed methods, that is, it does not mean that the present invention can only be implemented depending on the above-mentioned detailed methods. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

Claims (14)

1. A silicon nitride film material, characterized in that, the thickness of the silicon nitride film material is 107-110nm; and within the scope of the four-inch substrate, the film non-uniformity is lower than 1.0%; Wherein, the calculation method of the inhomogeneity is: film inhomogeneity=(maximum value-minimum value)/(average value×2)×100%, within the scope of the four-inch substrate, the measured number of different points is not less than 17 ; The silicon nitride film material is prepared by the following method: Place the substrate in the chamber of high-density plasma enhanced chemical vapor deposition equipment, pass through ammonia and silane as reaction gases, pass through argon as carrier and protective gas, and perform vapor deposition to obtain silicon nitride film materials; Among them, the working temperature of the high-density plasma-enhanced chemical vapor deposition equipment cavity is controlled to be 50-80°C, the working pressure is 3-5Pa, and the power is 390-460W; Wherein, the vapor deposition time is 5-7 minutes; the volume ratio of silane to ammonia is 14-18, and the volume ratio of silane to argon is 0.5-5. 2 . The silicon nitride film material according to claim 1 , wherein the composition of the silicon nitride film material is SiN _x , where 1≤x≤2. 3. a preparation method of silicon nitride film material as claimed in claim 1 or 2, is characterized in that, described method is: Place the substrate in the chamber of high-density plasma enhanced chemical vapor deposition equipment, pass through ammonia and silane as reaction gases, pass through argon as carrier and protective gas, and perform vapor deposition to obtain silicon nitride film materials; Among them, the working temperature of the high-density plasma-enhanced chemical vapor deposition equipment cavity is controlled to be 50-80°C, the working pressure is 3-5Pa, and the power is 390-460W; Wherein, the vapor deposition time is 5-7 minutes; the volume ratio of silane to ammonia is 14-18, and the volume ratio of silane to argon is 0.5-5. 4. The method for preparing a silicon nitride film material according to claim 3, wherein the substrate is any one of P-type doped single crystal silicon, N-type doped single crystal silicon or metal; Or prepare a layer of uniform metal or non-metal thin film on the above substrate as the substrate. 5. the preparation method of silicon nitride film material as claimed in claim 4 is characterized in that, described P-type doped monocrystalline silicon or N-type doped monocrystalline silicon substrate carries out following pretreatment: soak with HF acid Rinse with deionized water and dry. 6. The method for preparing a silicon nitride film material according to claim 5, characterized in that the mass concentration of the HF acid is 2-10%. 7. The preparation method of silicon nitride film material as claimed in claim 6, characterized in that, the mass concentration of the HF acid is 5%. 8 . The method for preparing a silicon nitride film material according to claim 5 , wherein the soaking time with HF acid is 0.5-10 min. 9. The preparation method of silicon nitride film material as claimed in claim 8, characterized in that, the soaking time with HF acid is 3 min. 10. the preparation method of silicon nitride membrane material as claimed in claim 4 is characterized in that, described metal substrate carries out following pretreatment: ultrasonically cleans respectively with acetone and Virahol, then drys; Described ultrasonic time is preferably for 5min. 11. the preparation method of silicon nitride film material as claimed in claim 3 is characterized in that, the purity of described silane, argon and ammonia is all greater than 99.99%; In the preparation method of described silicon nitride film material, Control the operating temperature of the high-density plasma-enhanced chemical vapor deposition equipment cavity to 65°C, the operating pressure to 4Pa, and the power to 410W; the vapor deposition time is 6.5min; the volume ratio of SiH ₄ to NH ₃ is 16.5 , the volume ratio of _SiH4 to argon is 1.0. 12. the preparation method of silicon nitride film material as claimed in claim 3 is characterized in that, described method comprises the steps: (1) Place the substrate in the cavity of the high-density plasma enhanced chemical vapor deposition equipment, evacuate the vacuum so that the vacuum degree of the back and the bottom is 1×10 ^-4 ~ 1×10 ^-6 Pa, and heat the substrate to 50~60°C ; (2) According to the volume ratio of 1: (14 ~ 18), feed ammonia and SiH ₄ as the reaction gas, feed argon as the carrier gas and protective gas, adjust the working pressure to 3 ~ 5Pa, and the power to 390 ~ 460W, Conduct chemical vapor deposition for 5-7 minutes; (3) Under the atmosphere of protective gas, reduce to room temperature, obtain the silicon nitride film material described in claim 1 or 2. 13. The method for preparing a silicon nitride film material according to claim 12, wherein the protective gas in step 3) is an inert gas. 14. A kind of purposes of silicon nitride film material as claimed in claim 1 or 2, it is characterized in that, described silicon nitride film material is used as insulating layer, protective film or optical film, is applied to semiconductor, microwave, optoelectronics and field of optics.