Method for regulating and controlling content of nitrogen and oxygen in silicon nitride, product and application

Abstract

The invention belongs to the technical field of silicon nitride preparation, and particularly relates to a method for regulating and controlling the content of nitrogen and oxygen in silicon nitride, a product and application of the product. And carrying out heat treatment on the ball-milled silicon nitride in a nitrogen-oxygen mixed gas atmosphere at the temperature of 800-1500 DEG C, and keeping the temperature for 5-60 minutes, so as to regulate and control the content of nitrogen and oxygen in the silicon nitride. Silicon nitride as a raw material is subjected to ball milling and then is subjected to heat treatment in nitrogen-oxygen mixed gas, so that the nitrogen-oxygen content of silicon nitride can be quickly regulated and controlled, a series of silicon nitride with different nitrogen-oxygen contents can be obtained by changing the heat treatment time and the nitrogen-oxygen mixed gas ratio, the raw material requirement is low, the reaction is quick and simple, and the cost is relatively low.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicon nitride preparation, and specifically relates to a method, a product and an application of regulating the nitrogen and oxygen content in silicon nitride. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Standard samples, sometimes called reference materials, are materials or substances with one or more sufficiently uniform and well-defined characteristic values ​​for calibrating measuring devices, evaluating measurement methods, or assigning values ​​to materials. It can be a pure or mixed gas, fluid, or solid. ISO Guide 30:1992 also gives the definition of certified reference samples: Standard samples with certificates, one or more of whose characteristic values ​​are determined by established traceability procedures, so that they can be traced back to accurately reproduced measurement units used to express the characteristic values, and each standard value is accompanied by an uncertainty with a given confidence level. Standard samples are widely used in measurement quality assurance, product quality management, measurement method evaluation, and the scientific formulation and effective implementation of regulations.

[0004] Silicon nitride (Si3N4) is a typical strong covalent bond compound. It not only has a high melting point, high hardness, and wear resistance, but also has high bending strength and good thermal conductivity. It has an irreplaceable position in key fields such as national defense, military industry, and electronic information, and is considered to be the ceramic material with the best comprehensive performance. The high strength and thermal shock resistance of Si3N4 copper-clad substrates give electronic devices a longer service life and reliability, and it is favored in high-power IGBT module packaging.

[0005] In addition to silicon and nitrogen, silicon nitride also contains a small amount of oxygen. The nitrogen and oxygen content in silicon nitride has an important influence on its performance. By preparing standard samples with different nitrogen and oxygen contents, the element content of newly prepared silicon nitride can also be quickly determined to ensure the quality of silicon nitride. There are several main methods for preparing silicon nitride: using pure silicon powder to synthesize silicon nitride powder at high temperature in a nitrogen atmosphere; using silicon halides or hydrogen halides or silane to react with ammonia to produce silicon nitride; mixing silicon dioxide with carbon powder and synthesizing silicon nitride at high temperature in a nitrogen atmosphere. The first two methods can adjust the nitrogen content in silicon nitride by adjusting the ratio of nitrogen or ammonia, but it is difficult to adjust the oxygen content of silicon nitride. Although the nitrogen and oxygen content in silicon nitride can be adjusted by the ratio of silicon dioxide and nitrogen, the synthesis process is energy-consuming and time-consuming, and it is difficult to achieve rapid and precise regulation. The obtained silicon nitride cannot meet the requirements of standard samples. Summary of the invention

[0006] In order to solve the deficiencies of the prior art, the purpose of the present invention is to provide a method, product and application for regulating the nitrogen and oxygen content in silicon nitride.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0008] In a first aspect, a method for controlling the nitrogen and oxygen content in silicon nitride using a nitrogen and oxygen mixed gas comprises the following steps:

[0009] The silicon nitride powder is ball-milled; the ball-milled silicon nitride is heat-treated in a nitrogen-oxygen mixed gas atmosphere at a temperature of 800 to 1500° C. for 5 to 60 minutes to achieve regulation of the nitrogen and oxygen content in the silicon nitride.

[0010] Preferably, the ball milling speed is 250-350 rpm, the ball milling time is 7-9 h, and the ball-to-material ratio is (3-5):1.

[0011] Preferably, the milling medium comprises ethanol.

[0012] Preferably, the ball-milled silicon nitride powder is dried.

[0013] More preferably, the drying temperature is 30-50° C., and the drying is vacuum drying.

[0014] Preferably, the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixture is (90-99):(10-1).

[0015] More preferably, the heat treatment temperature is 1000-1500° C., and the holding time is 15-60 min.

[0016] In a second aspect, a silicon nitride is obtained by the preparation method as described in the first aspect.

[0017] A third aspect is the use of the method described in the first aspect in the preparation of silicon nitride.

[0018] The beneficial effects achieved by one or more technical solutions of the present invention are as follows:

[0019] The nitrogen and oxygen content of silicon nitride can be quickly adjusted by ball milling silicon nitride as raw material and then heat treating it in a nitrogen and oxygen mixture. The degree of reaction between silicon nitride and oxygen at different temperatures during the heat treatment process is different, and nitrogen is used to prevent excessive oxidation. At the same time, a series of silicon nitrides with different nitrogen and oxygen contents can be obtained by changing the heat treatment parameters and the ratio of the nitrogen and oxygen mixture. The raw material requirements are low, the reaction is fast and simple, and the cost is low.

[0020] By regulating the nitrogen and oxygen content of silicon nitride through a nitrogen and oxygen mixed gas, a series of silicon nitrides with different nitrogen and oxygen contents are obtained, which can be used as silicon nitride standard samples for determining the nitrogen and oxygen content of silicon nitride, thereby reducing the difficulty and cost of obtaining standard samples. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in combination with specific embodiments and comparative examples.

[0022] Example 1

[0023] Silicon nitride powder with a purity of 99% and a particle size of 1 μm was selected as the raw material. The silicon nitride powder was mixed with alcohol and added to a ball mill for 8 hours. The ball mill speed was 300r / min and the ball-to-material ratio was 4:1. The slurry after ball milling was placed in a vacuum drying oven and vacuum dried at 40°C to obtain dried silicon nitride powder. The dried silicon nitride powder was placed in a corundum crucible and heat treated at 1500°C for 60 minutes in a nitrogen-oxygen mixed gas with a volume ratio of nitrogen to oxygen of 99:1 to adjust the nitrogen and oxygen content of silicon nitride.

[0024] Example 2

[0025] Silicon nitride powder with a purity of 99% and a particle size of 1 μm was selected as the raw material. The silicon nitride powder was mixed with alcohol and added to a ball mill for 8 hours. The ball mill speed was 300r / min and the ball-to-material ratio was 4:1. The slurry after ball milling was placed in a vacuum drying oven and vacuum dried at 40°C to obtain dried silicon nitride powder. The dried silicon nitride powder was placed in a corundum crucible and heat treated at 1300°C for 60 minutes in a nitrogen-oxygen mixed gas with a volume ratio of nitrogen to oxygen of 99:1 to adjust the nitrogen and oxygen content of silicon nitride.

[0026] Example 3

[0027] Silicon nitride powder with a purity of 99% and a particle size of 1 μm was selected as the raw material. The silicon nitride powder was mixed with alcohol and added to a ball mill for 8 hours. The ball mill speed was 300r / min and the ball-to-material ratio was 4:1. The slurry after ball milling was placed in a vacuum drying oven and vacuum dried at 40°C to obtain dried silicon nitride powder. The dried silicon nitride powder was placed in a corundum crucible and heat treated at 1000°C for 60 minutes in a nitrogen-oxygen mixed gas with a volume ratio of nitrogen to oxygen of 99:1 to adjust the nitrogen and oxygen content of silicon nitride.

[0028] Example 4

[0029] Silicon nitride powder with a purity of 99% and a particle size of 1 μm was selected as the raw material. The silicon nitride powder was mixed with alcohol and added to a ball mill for 8 hours. The ball mill speed was 300 r / min and the ball-to-material ratio was 4:1. The slurry after ball milling was placed in a vacuum drying oven and vacuum dried at 40°C to obtain dried silicon nitride powder. The dried silicon nitride powder was placed in a corundum crucible and heat treated at 800°C for 60 minutes in a nitrogen-oxygen mixed gas with a volume ratio of nitrogen to oxygen of 99:1 to adjust the nitrogen and oxygen content of silicon nitride.

[0030] Example 5

[0031] Silicon nitride powder with a purity of 99% and a particle size of 1 μm was selected as the raw material. The silicon nitride powder was mixed with alcohol and added to a ball mill for 8 hours. The ball mill speed was 300 r / min and the ball-to-material ratio was 4:1. The slurry after ball milling was placed in a vacuum drying oven and vacuum dried at 40°C to obtain dried silicon nitride powder. The dried silicon nitride powder was placed in a corundum crucible and heat treated at 1500°C for 5 minutes in a nitrogen-oxygen mixed gas with a volume ratio of nitrogen to oxygen of 99:1 to adjust the nitrogen and oxygen content of silicon nitride.

[0032] Example 6

[0033] Silicon nitride powder with a purity of 99% and a particle size of 1 μm was selected as the raw material. The silicon nitride powder was mixed with alcohol and added to a ball mill for 8 hours. The ball mill speed was 300 r / min and the ball-to-material ratio was 4:1. The milled slurry was placed in a vacuum drying oven and vacuum dried at 40°C to obtain dried silicon nitride powder. The dried silicon nitride powder was placed in a corundum crucible and heat treated at 1500°C for 60 minutes in a nitrogen-oxygen mixed gas with a volume ratio of nitrogen to oxygen of 97:3 to adjust the nitrogen and oxygen content of silicon nitride.

[0034] Example 7

[0035] Silicon nitride powder with a purity of 99% and a particle size of 1 μm was selected as the raw material. The silicon nitride powder was mixed with alcohol and added to a ball mill for 8 hours. The ball mill speed was 300r / min and the ball-to-material ratio was 4:1. The slurry after ball milling was placed in a vacuum drying oven and vacuum dried at 40°C to obtain dried silicon nitride powder. The dried silicon nitride powder was placed in a corundum crucible and heat treated at 1500°C for 60 minutes in a nitrogen-oxygen mixed gas with a volume ratio of nitrogen and oxygen of 95:5 to adjust the nitrogen and oxygen content of silicon nitride.

[0036] Example 8

[0037] Silicon nitride powder with a purity of 99% and a particle size of 1 μm was selected as the raw material. The silicon nitride powder was mixed with alcohol and added to a ball mill for 8 hours. The ball mill speed was 300r / min and the ball-to-material ratio was 4:1. The slurry after ball milling was placed in a vacuum drying oven and vacuum dried at 40°C to obtain dried silicon nitride powder. The dried silicon nitride powder was placed in a corundum crucible and heat treated at 1500°C for 60 minutes in a nitrogen-oxygen mixed gas with a volume ratio of nitrogen to oxygen of 92:8 to adjust the nitrogen and oxygen content of silicon nitride.

[0038] Example 9

[0039] Silicon nitride powder with a purity of 99% and a particle size of 1 μm was selected as the raw material. The silicon nitride powder was mixed with alcohol and added to a ball mill for 8 hours. The ball mill speed was 300r / min and the ball-to-material ratio was 4:1. The slurry after ball milling was placed in a vacuum drying oven and vacuum dried at 40°C to obtain dried silicon nitride powder. The dried silicon nitride powder was placed in a corundum crucible and heat treated at 1500°C for 60 minutes in a nitrogen-oxygen mixed gas with a volume ratio of nitrogen to oxygen of 90:10 to adjust the nitrogen and oxygen content of silicon nitride.

[0040] Example 10

[0041] Silicon nitride powder with a purity of 99% and a particle size of 1 μm was selected as the raw material. The silicon nitride powder was mixed with alcohol and added to a ball mill for 8 hours. The ball mill speed was 300r / min and the ball-to-material ratio was 4:1. The slurry after ball milling was placed in a vacuum drying oven and vacuum dried at 40°C to obtain dried silicon nitride powder. The dried silicon nitride powder was placed in a corundum crucible and heat treated at 1500°C for 60 minutes in a nitrogen-oxygen mixed gas with a volume ratio of nitrogen to oxygen of 80:20 to adjust the nitrogen and oxygen content of silicon nitride.

[0042] The nitrogen and oxygen contents (mass percentage) of the regulated silicon nitrides of Examples 1 to 10 were compared with the unregulated silicon nitride, and the results are shown in Table 1.

[0043] Table 1 Nitrogen and oxygen content of silicon nitride before and after regulation in different embodiments (in mass percentage)

[0044]

[0045] As shown in Table 1, it can be seen from Examples 1-5 that the reaction temperatures of silicon nitride in nitrogen atmosphere and oxygen atmosphere are different. At 800°C, it gradually reacts slowly with oxygen, and the reaction degree intensifies as the temperature rises. It starts to react with nitrogen at 1400-1500°C to reduce the oxygen content. Therefore, the reaction can be controlled by adjusting the reaction temperature to adjust the nitrogen and oxygen content.

[0046] As can be seen from Examples 1 and 6-9, the reaction can be controlled by adjusting the nitrogen-oxygen ratio of the mixed gas, and the nitrogen-oxygen content can be adjusted. The higher the oxygen content in the mixed gas, the higher the oxygen content in the silicon nitride. And because the reaction temperature of oxygen in the mixed gas is lower, oxygen occupies the main part of the reaction.

[0047] It can be seen from Example 10 that under this process, nitrogen hardly participates in the reaction, and silicon nitride is basically oxidized to silicon oxide. When the volume ratio of nitrogen to oxygen in the mixed gas exceeds the corresponding range, the nitrogen and oxygen content cannot be adjusted.

[0048] Comparative Example 1

[0049] Silicon nitride powder with a purity of 99% and a particle size of 1 μm was selected as the raw material. The silicon nitride powder was mixed with alcohol and added to a ball mill for 8 hours. The ball mill speed was 300r / min and the ball-to-material ratio was 4:1. The slurry after ball milling was placed in a vacuum drying oven and vacuum dried at 40°C to obtain dried silicon nitride powder. The dried silicon nitride powder was placed in a corundum crucible and heat treated at 1500°C in oxygen for 60 minutes. The oxygen content in silicon nitride increased sharply and silicon nitride was severely oxidized.

[0050] Comparative Example 2

[0051] Silicon nitride powder with a purity of 99% and a particle size of 1 μm was selected as the raw material. The silicon nitride powder was mixed with alcohol and added to a ball mill for 8 hours. The ball mill speed was 300r / min and the ball-to-material ratio was 4:1. The milled slurry was placed in a vacuum drying oven and vacuum dried at 40°C to obtain dried silicon nitride powder. The dried silicon nitride powder was placed in a corundum crucible and heat treated at 1500°C in nitrogen for 60 minutes. The oxygen content in silicon nitride decreased and the nitrogen content increased.

[0052] Comparative Example 3

[0053] Silicon nitride powder with a purity of 99% and a particle size of 1 μm was selected as the raw material. The silicon nitride powder was mixed with alcohol and added to a ball mill for 8 hours. The ball mill speed was 300r / min and the ball-to-material ratio was 4:1. The slurry after ball milling was placed in a vacuum drying oven and vacuum dried at 40°C to obtain dried silicon nitride powder. The dried silicon nitride powder was placed in a corundum crucible and heat treated at 1500°C in argon for 60 minutes. The nitrogen and oxygen content in the silicon nitride was almost unchanged.

[0054] It can be seen from Example 1 and Comparative Examples 1-3 that the participation of nitrogen can weaken the reaction intensity and make the oxygen content of silicon nitride more precisely regulated; the mixed gas ratio and temperature have a synergistic effect, both of which aim to control the intensity of the reaction and make the change of the oxygen content more precisely controlled.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for regulating the nitrogen and oxygen content in silicon nitride, characterized in that: The following steps are involved: The silicon nitride powder is ball-milled; the ball-milled silicon nitride is heat-treated in a nitrogen-oxygen mixed gas atmosphere at a temperature of 800 to 1500° C. for 5 to 60 minutes to achieve regulation of the nitrogen and oxygen content in the silicon nitride.

2. The method for controlling the nitrogen and oxygen content in silicon nitride according to claim 1, characterized in that: The ball milling speed is 250-350 rpm, the ball milling time is 7-9 h, and the ball-to-material ratio is (3-5):

1.

3. The method for controlling the nitrogen and oxygen content in silicon nitride according to claim 1, characterized in that: The ball milling media included ethanol.

4. The method for controlling nitrogen and oxygen content in silicon nitride according to claim 1, characterized in that: The ball-milled silicon nitride powder is dried.

5. The method for controlling the nitrogen and oxygen content in silicon nitride according to claim 4, characterized in that: The drying temperature is 30-50°C, and the drying is vacuum drying.

6. The method for controlling nitrogen and oxygen content in silicon nitride according to claim 1, characterized in that: The volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixture is (90-99):(10-1).

7. The method for controlling nitrogen and oxygen content in silicon nitride according to claim 1, characterized in that: The heat treatment temperature is 1000-1500°C and the holding time is 15-60 minutes.

8. A silicon nitride, characterized in that: Obtained by the method according to any one of claims 1 to 7.

9. Use of the method according to any one of claims 1 to 7 in the preparation of silicon nitride.

Images