Silicon nitride green body and preparation method and application thereof
By adding a wetting agent and a penetrant to the silicon nitride green body, performing two ball milling and vacuum degassing treatments, and combining it with tape casting in a solvent atmosphere, the problems of warping, wrinkling, and cracking caused by high-solid content slurry are solved, the yield and performance of the silicon nitride green body are improved, and it is suitable for the semiconductor field.
Patent Information
- Application Number
- CN202510946194.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-09
- Publication Date
- 2025-09-19
AI Technical Summary
The high solid content of silicon nitride slurry causes problems such as warping, wrinkling, and cracking in the green embryo after tape casting and drying, reducing the product yield.
By adding a wetting agent and a penetrant to the silicon nitride green body, controlling its total mass to be greater than or equal to 1% of the silicon nitride powder, and performing two ball milling and vacuum degassing treatments, combined with tape casting in a solvent atmosphere, the dispersion and uniformity of the slurry are optimized.
It effectively reduces the warping, wrinkling and cracking of the silicon nitride green body, improves the yield rate, and enhances the thermal conductivity and corrosion resistance of the silicon nitride green body, and is suitable for the semiconductor field.
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] The present application relates to the field of materials, and in particular to a silicon nitride green body and a preparation method and application thereof. Background Art
[0002] In the modern electronics industry, the choice of substrate material has a crucial impact on the heat dissipation and stability of devices. Compared to traditional resin substrate materials, silicon nitride ceramic materials have been widely promoted due to their excellent properties such as high thermal conductivity, low thermal expansion coefficient, and high mechanical strength. In addition, the chemical stability and corrosion resistance of silicon nitride also give it a longer service life in harsh environments. To achieve large-scale production, the slurry is usually subjected to a casting process and then a drying and sintering process to prepare the silicon nitride ceramic substrate material. Among them, the use of a high-solids content slurry for homogenization and casting can effectively improve the dimensional accuracy and mechanical properties of the product.
[0003] However, the high solid content slurry has a higher viscosity, resulting in poor slurry dispersion, which ultimately leads to different shrinkage degrees of different parts of the green embryo obtained by cast drying, resulting in problems such as warping, wrinkling, and cracking, reducing the product yield. Summary of the Invention
[0004] The present application provides a silicon nitride green body. By limiting its composition, even if a high-viscosity slurry is subjected to cast drying, a green body with a better molding state can be obtained, effectively reducing the problems of warping, wrinkling, and cracking.
[0005] The present application also provides a method for preparing a silicon nitride green body, which effectively improves the yield rate of the silicon nitride green body through a simple preparation process and is suitable for industrial production.
[0006] The present application also provides a silicon nitride ceramic substrate, which has better thermal conductivity and corrosion resistance and is suitable for the semiconductor field.
[0007] The present application also provides a semiconductor device having better heat dissipation and stability.
[0008] The present application provides a silicon nitride green body, comprising silicon nitride powder, a penetrant, and a wetting agent, wherein the penetrant comprises at least one of fatty alcohol polyoxyethylene ether and nonylphenol polyoxyethylene ether, and the wetting agent comprises at least one of triolein, monoolein, and fatty acid polyoxyethylene ester, wherein the total mass of the wetting agent and the penetrant is greater than or equal to 1% of the mass of the silicon nitride powder.
[0009] In the silicon nitride green body described above, the total mass of the wetting agent and the penetrant is less than or equal to 3% of the mass of the silicon nitride powder; and / or the mass of the wetting agent is greater than or equal to 0.5% of the mass of the silicon nitride powder, and the mass of the penetrant is greater than or equal to 0.5% of the mass of the silicon nitride powder.
[0010] The silicon nitride green body as described above further includes a dispersant, a binder, a plasticizer, a sintering aid, and an organosilicon degassing agent, and the mass ratio of the silicon nitride powder, the penetrant, the dispersant, the binder, the wetting agent, the plasticizer, the sintering aid, and the organosilicon degassing agent is 100:(0.2-1):(2-4):(5-10):(0.2-1):(5-7):(5-7):(1-2).
[0011] The silicon nitride green body as described above, wherein the D50 of the silicon nitride powder is 0.5-1 μm; and / or the dispersant includes at least one of triethyl phosphate, polyacrylamide, and polyethylene glycol; and / or the binder includes at least one of polyvinyl butyral, polyvinyl chloride, polyvinyl alcohol, and polymethacrylate; and / or the plasticizer includes at least one of polyethylene glycol, dioctyl oxalate, dioctyl phthalate, and dibutyl phthalate; and / or the sintering aid includes at least two of magnesium oxide, yttrium oxide, and calcium oxide; and / or the organosilicon defoaming agent includes at least one of dimethylsiloxane, dimethylsilane, and polysiloxane; and / or the thickness of the silicon nitride green body is 0.3-1 mm.
[0012] The present application also provides a method for preparing the silicon nitride green body described in any of the above items, comprising the following steps: ball-milling a mixture comprising the silicon nitride powder, a penetrant, and a wetting agent to obtain a raw material slurry, and performing a tape casting process on the raw material slurry to obtain a silicon nitride green body.
[0013] The preparation method as described above, before the tape casting process, comprises the following steps:
[0014] 1) ball milling a first mixed solution comprising silicon nitride powder, a sintering aid, a dispersant, a penetrant, and a first solvent to obtain a first slurry;
[0015] 2) adding a second mixed solution comprising a plasticizer, a binder, a wetting agent, and a second solvent to the first slurry and performing secondary ball milling to obtain a second slurry;
[0016] 3) adding an organosilicon degassing agent to the second slurry for vacuum degassing to obtain the raw material slurry.
[0017] The preparation method as described above, in the primary ball milling and / or secondary ball milling, the ball milling medium is a silicon nitride ball with a particle size of 3 to 5 mm, and the rotation speed is 150 to 200 r / min; and / or the vacuum degassing comprises: -2 ~10 -1 Vacuum degassing is performed at a vacuum degree of 0.5 Pa to obtain a raw material slurry with a viscosity of 2000-8000 mPa·s; and / or the first solvent and the second solvent include an alcohol solvent and a benzene-ketone mixed solvent in a mass ratio of 1:(1-10); and / or the total mass of the first solvent and the second solvent is 60-100% of the mass of the silicon nitride powder.
[0018] In the above-mentioned preparation method, the tape casting process is performed in a solvent atmosphere.
[0019] The present application also provides a silicon nitride ceramic substrate, which is prepared from the silicon nitride green body described in any one of the above items, or the silicon nitride green body prepared by any one of the above preparation methods.
[0020] The present application also provides a semiconductor device, comprising the above-mentioned silicon nitride ceramic substrate and a semiconductor layer arranged on the silicon nitride ceramic substrate.
[0021] The silicon nitride green body provided in the present application, by limiting the composition of the wetting agent and the penetrant and the total mass being greater than or equal to 1% of the mass of the silicon nitride powder, can maintain a high solid content under the synergistic effect of the wetting agent and the penetrant while effectively reducing the problems of warping, wrinkling, and cracking, and has a wider range of applications. DETAILED DESCRIPTION
[0022] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.
[0023] The quality of silicon nitride green sheets is often determined by their molding state. However, current silicon nitride green sheets often suffer from warping, wrinkling, and cracking after molding, making subsequent work difficult. The inventors believe that the dispersion of solid particles in the silicon nitride green sheet is the key factor affecting its molding state. To improve the dispersion of solid particles in the silicon nitride green sheet, the inventors have attempted to regulate the composition of the silicon nitride green sheet to improve the dispersion and uniformity of the solid particles.
[0024] Based on this, the present application provides a silicon nitride green body, comprising: silicon nitride powder, a penetrant and a wetting agent, wherein the penetrant comprises at least one of fatty alcohol polyoxyethylene ether and nonylphenol polyoxyethylene ether, and the wetting agent comprises at least one of triolein, monoolein, and fatty acid polyoxyethylene ester, wherein the total mass of the wetting agent and the penetrant is greater than or equal to 1% of the mass of the silicon nitride powder.
[0025] The molecular formula of fatty alcohol polyoxyethylene ether in the penetrant is RO-(CH2CH2O) n -H, wherein R is any saturated or unsaturated C12~18 hydrocarbon group, which can be a straight chain hydrocarbon group or a branched hydrocarbon group, and n≥1. For example, it can be at least one of fatty alcohol polyoxyethylene ether 3 ether, fatty alcohol polyoxyethylene ether 7 ether and fatty alcohol polyoxyethylene ether 9 ether; the molecular formula of fatty acid polyoxyethylene ester in the wetting agent is ROO-(CH2CH2O) m -H, wherein R is any saturated or unsaturated hydrocarbon group of C1 to 30, which may be a straight-chain hydrocarbon group or a branched hydrocarbon group, and m≥1.
[0026] The present application does not impose excessive restrictions on the molecular weight of the polymers in the various specific compounds in the penetrant and wetting agent. When making a specific selection, the specific compound can be selected based on the dispersion effect of the particles in the silicon nitride green body and the cost. The silicon nitride green body of the present application effectively improves the molding state of the silicon nitride green body, and the problems of warping, wrinkling, and cracking are significantly reduced.
[0027] The silicon nitride green body prepared in the present application reduces the surface tension of the slurry before green body molding by synergistically matching at least one of the penetrants and at least one of the wetting agents as functional improvers, and controlling the total mass of the two functional improvers to be greater than or equal to 1% of the mass of the silicon nitride powder. At the same time, it reduces the surface energy of the solid particles and improves the dispersion effect of the silicon nitride particles in the slurry. Therefore, the quality of the silicon nitride green body after the slurry is dried and formed is significantly improved.
[0028] The inventors have found that when the total mass of the wetting agent and the penetrant is less than or equal to 3% of the mass of the silicon nitride powder, the low binder content can be maintained, reducing the difficulty of the subsequent binder removal and sintering process of the silicon nitride green body.
[0029] In addition, when the mass of the wetting agent is greater than or equal to 0.5% of the mass of the silicon nitride powder, and the mass of the penetrant is greater than or equal to 0.5% of the mass of the silicon nitride powder, the optimization effect on the green body molding is more significant, which can further improve the yield rate of the silicon nitride green body.
[0030] In order to further improve the quality of the silicon nitride green body and reduce the risks of warping, wrinkling and cracking, the silicon nitride green body of the present application also includes a dispersant, an adhesive, a plasticizer, a sintering aid, and an organosilicon degassing agent, and the mass ratio of silicon nitride powder, penetrant, dispersant, adhesive, wetting agent, plasticizer, sintering aid, and organosilicon degassing agent is 100:(0.2-1):(2-4):(5-10):(0.2-1):(5-7):(5-7):(1-2).
[0031] The inventors have found that when the D50 of the silicon nitride powder is 0.5-1 μm, the dispersion effect of the silicon nitride powder in the silicon nitride green body is better, and the quality of the silicon nitride green body is better.
[0032] In a specific embodiment of the present application, when the dispersant includes at least one of triethyl phosphate, polyacrylamide, and polyethylene glycol, the silicon nitride powder is better dispersed in the silicon nitride green body and the chemical stability of the silicon nitride green body is better.
[0033] In addition, when the binder includes at least one of polyvinyl butyral, polyvinyl chloride, polyvinyl alcohol, and polymethacrylate, the silicon nitride powder is more evenly distributed in the silicon nitride green body, and the mechanical strength of the silicon nitride green body is higher.
[0034] Furthermore, when the plasticizer includes at least one of polyethylene glycol, dioctyl oxalate, dioctyl phthalate, and dibutyl phthalate, the flexibility of the silicon nitride green body is better.
[0035] Furthermore, when the sintering aid includes at least two of magnesium oxide, yttrium oxide, and calcium oxide, the silicon nitride green body has higher structural stability.
[0036] Furthermore, when the organic silicon degassing agent includes at least one of dimethylsiloxane and polysiloxane, the number of bubble defects in the silicon nitride green body is reduced.
[0037] The present application does not limit the specific ratios of the various compounds in the sintering aid, nor does it impose excessive restrictions on the molecular weight of the polymers in the various specific compounds in the above components. When making a specific selection, the selection can be made based on the beneficial effects of the specific compound on the silicon nitride green body molding state and the cost.
[0038] The inventors have found that the thickness of the silicon nitride green body also affects the molding state of the silicon nitride green body. Specifically, when the thickness of the silicon nitride green body is 0.3-1 mm, the risk of warping, wrinkling, and cracking of the silicon nitride green body is lower.
[0039] The present application also provides a method for preparing the aforementioned silicon nitride green body, comprising the following steps: ball-milling a mixture comprising silicon nitride powder, a penetrant, and a wetting agent to obtain a raw material slurry, and subjecting the raw material slurry to a tape-casting molding process to obtain a silicon nitride green body having a better molding state.
[0040] The present application does not limit the order of adding the components, as long as the components in the raw material slurry including the silicon nitride powder, penetrant and wetting agent are mixed evenly.
[0041] It is understood that in addition to the silicon nitride powder, penetrant, and wetting agent, the raw material slurry also includes a solvent to ensure the fluidity of the slurry. During the preparation process, the silicon nitride powder, penetrant, and wetting agent can be added to the solvent simultaneously to obtain the raw material slurry. Alternatively, one or two of the silicon nitride powder, penetrant, and wetting agent can be added to the solvent first, and then the remaining portion is added to the aforementioned system.
[0042] In addition, when the silicon nitride green body further includes at least one of a dispersant, a binder, a plasticizer, a sintering aid, and a silicone degassing agent, the present application does not limit the order in which the silicon nitride powder, penetrant, wetting agent, dispersant, binder, plasticizer, sintering aid, and silicone degassing agent are added to the raw material slurry.
[0043] In order to further improve the yield rate of silicon nitride green embryos, in a specific embodiment, before the tape casting process, the following steps are included:
[0044] 1) ball milling a first mixed solution comprising silicon nitride powder, a sintering aid, a dispersant, a penetrant, and a first solvent to obtain a first slurry;
[0045] 2) adding a second mixed solution comprising a plasticizer, a binder, a wetting agent, and a second solvent to the first slurry and performing secondary ball milling to obtain a second slurry;
[0046] 3) Adding an organosilicon degassing agent to the second slurry for vacuum degassing to obtain a raw material slurry.
[0047] Silicon nitride particles are small in size and easily agglomerated and unevenly dispersed in the slurry, resulting in uneven quality of the silicon nitride green body after tape casting. Therefore, the present application strengthens the mixing degree of the slurry by two ball millings, and then vacuum degasses to obtain a raw material slurry. Ball milling a first mixed solution including silicon nitride powder, a sintering aid, a dispersant, a penetrant and a first solvent can promote the dispersion of solid particles in the first slurry, wherein the combination of the penetrant and the dispersant can better disperse the hard-to-disperse solid particles in the first slurry; in order to make the solid particles dispersed in the slurry more evenly distributed, a second mixed solution including a plasticizer, a binder, a wetting agent and a second solvent is added to the first slurry for a second ball milling, wherein the combination of the wetting agent and the binder can further promote the uniform distribution of the solid particles in the slurry. After two ball millings, the dispersion and uniformity of the solid particles in the slurry are effectively improved. After degassing the second slurry, the raw material slurry is obtained, and the yield rate of the silicon nitride green body obtained after tape casting is higher.
[0048] In order to improve the stirring efficiency of the solution, the second mixed liquid needs to be fully stirred and mixed until the solution becomes clear, wherein the stirring speed can be 150-200 r / min and the stirring time can be 12-24 h.
[0049] In addition, in order to further improve the dispersion effect of silicon nitride powder in the silicon nitride green body, the ball milling medium of the first ball milling is silicon nitride balls with a particle size of 3~5mm, the rotation speed is 150~200r / min, and the ball milling medium of the second ball milling is silicon nitride balls with a particle size of 3~5mm, the rotation speed is 150~200r / min, wherein the first ball milling time can be 24~48h, and the second ball milling time can be 24~48h.
[0050] Further, in order to obtain the raw material slurry that meets the requirements, vacuum degassing is included in 10 -2 ~10 -1 The vacuum degassing is performed under a vacuum degree of 0.175 % Pa to obtain a raw material slurry with a viscosity of 2000-8000 mPa·s, wherein the vacuum degassing time can be 1-3 hours.
[0051] The inventors have found that when a mixed solvent of an alcohol solvent and a benzene-ketone solvent in a mass ratio of 1:(1-10) is used as a dissolving solvent, the raw material slurry is less likely to crack during tape-cast drying. The present application does not limit the specific compound types or sources of the alcohol solvent and the benzene-ketone solvent. For example, the alcohol solvent can be at least one of ethanol, propanol, butanol, ethylene glycol, and isopropanol. The benzene-ketone solvent is a benzene solvent and a ketone solvent. The benzene solvent can be at least one of toluene and xylene. The ketone solvent can be at least one of cyclohexanone, butanone, dibutyl ketone, and methyl isobutyl ketone. Of course, when making a specific selection, the selection can be made based on the dissolution effect of the specific compound on each component and the cost.
[0052] In order to further improve the dissolution effect of the solvent on each component, the total mass of the first solvent and the second solvent is 60-100% of the mass of the silicon nitride powder. The present application does not limit the ratio of the first solvent and the second solvent. For example, the mass ratio of the first solvent to the second solvent can be 1:1. Of course, when making a specific selection, the selection can be made according to the dispersion effect of the solid particles in the slurry.
[0053] The inventors have discovered that performing the casting process in a volatile solvent atmosphere can slow the rate of solvent evaporation, further reducing the risk of cracking in the silicon nitride green body. The present application does not limit the configuration of the solvent atmosphere; for example, the casting process can be performed by allowing the volatile solvent to evaporate naturally, allowing the evaporated solvent to fill the casting drying chamber, or by continuously blowing in the solvent atmosphere while the casting process is performed.
[0054] As for the natural volatilization of the solvent, this application does not limit the type and source of the solvent, as long as it meets the characteristic of being volatile. Specifically, it can be at least one of ethanol, toluene, and n-hexane. The container of the volatile solvent is also not limited. Specifically, it can be a beaker or any other container that can hold the solvent. There are no excessive restrictions on the capacity and loading amount of the container and the volatilization time of the solvent. When making a specific choice, you can make a choice according to different preparation scales.
[0055] The casting equipment of the present application can specifically be a casting machine. The present application does not limit the knife height of the casting machine, the temperature of the drying zone and the flow rate of the conveyor belt. When making a specific selection, it can be selected according to the required thickness of the silicon nitride green body and the drying efficiency. Similarly, there is no excessive limitation on the drying time of the green body. When making a specific selection, it can be selected according to the thickness and area of the green body.
[0056] The present application also provides a silicon nitride ceramic substrate, which is prepared from the aforementioned silicon nitride green body, or the silicon nitride green body prepared by the aforementioned preparation method.
[0057] The present application does not limit the method for preparing a silicon nitride ceramic substrate from a silicon nitride green body. In a specific embodiment, the silicon nitride green body may be subjected to debinding and sintering treatments to obtain a silicon nitride ceramic substrate, which has better thermal conductivity and corrosion resistance.
[0058] The present application also provides a semiconductor device comprising a silicon nitride ceramic substrate and a semiconductor layer disposed on the silicon nitride ceramic substrate, wherein the silicon nitride ceramic substrate comprises the aforementioned silicon nitride ceramic substrate. The semiconductor device can be any structural component in the semiconductor field that requires heat dissipation and stability. Specifically, the semiconductor device can be, for example, a semiconductor memory device comprising a silicon nitride ceramic substrate and a memory chip disposed on the silicon nitride ceramic substrate. The semiconductor device has better stability, can achieve efficient heat dissipation, and has a wider range of applications.
[0059] Example 1
[0060] The method for preparing the silicon nitride green body comprises the following steps:
[0061] 1) Silicon nitride powder (D50: 0.5 μm), sintering aids (magnesium oxide and yttrium oxide), dispersant (polyacrylamide), penetrant (fatty alcohol polyoxyethylene ether 3), and first solvent (anhydrous ethanol and toluene in a mass ratio of 1:1) were mixed and added to a 500 mL ball mill. The ball milling medium was 3 mm silicon nitride balls. The speed was set to 200 rpm and the ball milling was performed for 24 hours to obtain the first slurry.
[0062] 2) Add the plasticizer (polyethylene glycol), binder (polyvinyl butyral), wetting agent (triolein), and second solvent (anhydrous ethanol and toluene in a 1:1 mass ratio) to a 200 mL beaker and stir to dissolve at 200 rpm. After 12 hours, a clear second mixed solution is obtained. The mass ratio of the first solvent to the second solvent is 1:1.
[0063] 3) The first slurry was added to the second mixed solution and subjected to secondary ball milling using silicon nitride balls with a particle size of 3 mm at a rotation speed of 200 rpm to obtain a second slurry;
[0064] 4) Pour the second slurry into a 200mL beaker, add degassing agent (dimethylsiloxane), and place in a vacuum degassing machine with a vacuum degree of 10 -2 ~10 -1 Pa for 1 hour to obtain a raw material slurry, wherein the mass ratio of silicon nitride powder, penetrant, dispersant, binder, wetting agent, plasticizer, sintering aid, silicone defoaming agent, and solvent is 100:0.5:4:8:0.5:5:5:2:90, and the mass ratio of magnesium oxide to yttrium oxide in the sintering aid is 1:1;
[0065] 5) Place two beakers (50 mL capacity, 40 mL loading) filled with a volatile solvent (ethanol: toluene = 1:1) on the steps on both sides of the casting machine. After 2 hours, slowly pour the raw material slurry into the casting machine trough, set the knife height to 0.5 mm, the drying zone temperature to 30 ° C, 35 ° C, and 40 ° C, respectively, and the conveyor belt flow rate to 2 cm / min. After the membrane surface is dried, the silicon nitride embryo is obtained.
[0066] Example 2
[0067] The method for preparing the silicon nitride green body comprises the following steps:
[0068] 1) Silicon nitride powder (D50: 0.5 μm), sintering aids (magnesium oxide and calcium oxide), dispersant (polyacrylamide), penetrant (nonylphenol polyoxyethylene ether), and a first solvent (anhydrous ethanol and xylene in a mass ratio of 1:2) were mixed and added to a 500 mL ball mill. The ball milling medium was 3 mm silicon nitride balls. The speed was set to 200 rpm and the ball milling was performed for 24 hours to obtain a first slurry.
[0069] 2) Add the plasticizer (dioctyl oxalate), binder (polyvinyl chloride), wetting agent (glycerol monooleate), and second solvent (anhydrous ethanol and xylene in a mass ratio of 1:2) to a 200 mL beaker and stir to dissolve at 180 rpm. After 15 hours, a clear second mixed solution is obtained. The mass ratio of the first solvent to the second solvent is 1:1.
[0070] 3) The first slurry was added to the second mixed solution and subjected to secondary ball milling using silicon nitride balls with a particle size of 3 mm at a rotation speed of 200 rpm to obtain a second slurry;
[0071] 4) Pour the second slurry into a 200mL beaker, add degassing agent (polysiloxane), and place in a vacuum degassing machine with a vacuum degree of 10 -2 ~10 -1 The raw material slurry was defoamed at 400 Pa for 1.5 hours to obtain a raw material slurry, wherein the mass ratio of silicon nitride powder, penetrant, dispersant, binder, wetting agent, plasticizer, sintering aid, silicone defoaming agent, and solvent was 100:0.4:4:8:0.6:5:5:1:80, and the mass ratio of magnesium oxide to calcium oxide in the sintering aid was 1:1;
[0072] 5) Place two beakers (50 mL capacity, 40 mL loading) filled with a volatile solvent (toluene: ethanol = 1:1) on the steps on both sides of the casting machine. After 2 hours, slowly pour the raw material slurry into the casting machine trough. Set the knife height to 0.6 mm, the drying zone temperature to 30 ° C, 35 ° C, and 40 ° C, respectively, and the conveyor belt flow rate to 4 cm / min. After the membrane surface is dried, the silicon nitride embryo is obtained.
[0073] Example 3
[0074] The method for preparing the silicon nitride green body comprises the following steps:
[0075] 1) Silicon nitride powder (D50: 0.6 μm), sintering aids (yttrium oxide and calcium oxide), dispersant (polyacrylamide), penetrant (nonylphenol polyoxyethylene ether), and a first solvent (anhydrous ethanol and toluene in a mass ratio of 1:4) were mixed and added to a 500 mL ball mill. The milling medium was 3 mm silicon nitride balls. The speed was set to 200 rpm and the milling was performed for 24 hours to obtain a first slurry.
[0076] 2) Add the plasticizer (dibutyl phthalate), binder (polyvinyl alcohol), wetting agent (triolein), and second solvent (anhydrous ethanol and toluene in a mass ratio of 1:4) to a 200 mL beaker and stir to dissolve at 200 rpm. After 16 hours, a clear second mixed solution is obtained. The mass ratio of the first solvent to the second solvent is 1:1.
[0077] 3) The first slurry was added to the second mixed solution and subjected to secondary ball milling using silicon nitride balls with a particle size of 3 mm at a rotation speed of 200 rpm to obtain a second slurry;
[0078] 4) Pour the second slurry into a 200mL beaker, add degassing agent (dimethylsilane), and place in a vacuum degassing machine with a vacuum degree of 10 -2 ~10 -1 The raw material slurry was defoamed at 400 Pa for 2 hours to obtain a raw material slurry, wherein the mass ratio of silicon nitride powder, penetrant, dispersant, binder, wetting agent, plasticizer, sintering aid, silicone defoaming agent, and solvent was 100:0.6:3:9:0.4:5:6:1.5:80, and the mass ratio of yttrium oxide to calcium oxide in the sintering aid was 1:1;
[0079] 5) Place two beakers (50 mL capacity, 40 mL loading) filled with a volatile solvent (toluene: ethanol = 1:1) on the steps on both sides of the casting machine. After 3 hours, slowly pour the raw material slurry into the casting machine trough. Set the knife height to 0.8 mm, the drying zone temperature to 30 ° C, 35 ° C, and 40 ° C, respectively, and the conveyor belt flow rate to 4 cm / min. After the membrane surface is dried, the silicon nitride embryo is obtained.
[0080] Example 4
[0081] The method for preparing the silicon nitride green body comprises the following steps:
[0082] 1) Silicon nitride powder (D50: 0.7 μm), sintering aids (magnesium oxide and yttrium oxide), dispersant (polyacrylamide), penetrant (fatty alcohol polyoxyethylene ether 7), and first solvent (isopropanol and toluene in a mass ratio of 1:6) were mixed and added to a 500 mL ball mill. The ball milling medium was 3 mm silicon nitride balls. The speed was set to 200 rpm and the ball milling was performed for 24 hours to obtain the first slurry.
[0083] 2) Add the plasticizer (dibutyl phthalate), binder (polymethacrylate), wetting agent (fatty acid polyoxyethylene ester), and second solvent (isopropyl alcohol and toluene in a mass ratio of 1:6) to a 200 mL beaker and stir to dissolve at 200 rpm. After 12 hours, a clear second mixed solution is obtained. The mass ratio of the first solvent to the second solvent is 1:1.
[0084] 3) The second mixed liquid was added to the first slurry and subjected to secondary ball milling using silicon nitride balls with a particle size of 3 mm at a rotation speed of 200 rpm to obtain a second slurry;
[0085] 4) Pour the second slurry into a 200mL beaker, add a degassing agent (polysiloxane, vacuum degree 10 in a vacuum degassing machine) -2 ~10 -1 Pa for 2 h to obtain a raw material slurry, wherein the mass ratio of silicon nitride powder, penetrant, dispersant, binder, wetting agent, plasticizer, sintering aid, silicone defoaming agent, and solvent is 100:0.8:4:8:0.8:5:6:2:60, and the mass ratio of magnesium oxide to yttrium oxide in the sintering aid is 1:1;
[0086] 5) Place two beakers (50 mL capacity, 30 mL loading) filled with a volatile solvent (toluene: ethanol = 1:1) on the steps on both sides of the casting machine. After 2 hours, slowly pour the raw material slurry into the casting machine trough. Set the knife height to 1 mm, the drying zone temperature to 30 ° C, 35 ° C, and 40 ° C, respectively, and the conveyor belt flow rate to 2 cm / min. After the membrane surface is dry, the silicon nitride embryo is obtained.
[0087] Example 5
[0088] The preparation method of the silicon nitride green body of this comparative example is basically the same as that of Example 1, except that the mass ratio of silicon nitride powder, penetrant, dispersant, binder, wetting agent, plasticizer, sintering aid, silicone defoaming agent, and solvent is 100:0.2:4:8:0.8:5:5:2:90.
[0089] Example 6
[0090] The preparation method of the silicon nitride green body in this comparative example is basically the same as that in Example 1, except that no solvent atmosphere is provided during the tape casting process.
[0091] Example 7
[0092] The preparation method of the silicon nitride green body in this comparative example is basically the same as that in Example 1, except that the D50 of the silicon nitride powder is 0.8 μm.
[0093] Example 8
[0094] The preparation method of the silicon nitride green body of this comparative example is basically the same as that of Example 1, except that the silicon nitride powder, sintering aid, dispersant, penetrant, first solvent, plasticizer, binder, wetting agent and second solvent are all mixed and then ball milled only once.
[0095] Example 9
[0096] The preparation method of the silicon nitride green body of this comparative example is basically the same as that of Example 1, except that the mass of the penetrant is 0.6% of the silicon nitride powder and the mass of the wetting agent is also 0.6% of the silicon nitride powder.
[0097] Example 10
[0098] The preparation method of the silicon nitride green body of this comparative example is basically the same as that of Example 1, except that the mass of the penetrant is 0.8% of the silicon nitride powder and the mass of the wetting agent is also 0.8% of the silicon nitride powder.
[0099] Comparative Example 1
[0100] The preparation method of the silicon nitride green body of this comparative example is basically the same as that of Example 1, except that the D50 of the silicon nitride powder is 0.7 μm, no solvent atmosphere is set during the tape casting process, and no wetting agent and penetrant are added.
[0101] Comparative Example 2
[0102] The preparation method of the silicon nitride green body in this comparative example is basically the same as that in Example 1, except that no wetting agent is added and the mass of the penetrant is 1% of the mass of the silicon nitride powder.
[0103] Comparative Example 3
[0104] The preparation method of the silicon nitride green body of this comparative example is basically the same as that of Example 1, except that no penetrant is added and the mass of the wetting agent is 1% of the mass of the silicon nitride powder.
[0105] Comparative Example 4
[0106] The preparation method of the silicon nitride green body in this comparative example is basically the same as that in Example 1, except that no penetrant and wetting agent are added.
[0107] Comparative Example 5
[0108] The preparation method of the silicon nitride green body in this comparative example is basically the same as that in Example 1, except that the mass of the penetrant is 0.4% of the mass of the silicon nitride powder, and the mass of the wetting agent is 0.4% of the mass of the silicon nitride powder.
[0109] Test Example 1
[0110] The viscosity of the raw material slurry, thickness of the silicon nitride green body, and yield rate of the above-mentioned examples and comparative examples were measured. The results are shown in Table 1. Table 1 also includes the mass ratio of the wetting agent and penetrant to the mass of the silicon nitride powder in the above-mentioned examples and comparative examples. The viscosity was measured using a rotational viscometer, the thickness was measured using an electronic thickness gauge, and the yield rate was calculated using the following formula: 1 - warpage × 20% - wrinkling × 30% - cracking × 50%. The warpage was measured using a three-dimensional coordinate measuring machine, and the wrinkling and cracking rates were measured using a two-dimensional measuring instrument.
[0111] Table 1
[0112]
[0113] From Table 1 we can see that:
[0114] 1. As can be seen from Example 1 and Comparative Examples 2-4, when no wetting agent and penetrant are added or only one of them is added, the yield rate of silicon nitride green body is significantly deteriorated, indicating that both are indispensable;
[0115] 2. It can be seen from Example 1 and Comparative Example 5 that when the total mass of the wetting agent and the penetrant added is greater than or equal to 1% of the silicon nitride powder, the yield rate of the silicon nitride green body is significantly improved, and when the total mass of the additives is less than 1% of the silicon nitride powder, the warpage rate is significantly improved;
[0116] 3. By comparing Examples 1, 5, 9, and 10, it can be seen that the addition ratio of the wetting agent and the penetrant affects the yield rate of the silicon nitride green body. When the mass of the wetting agent is greater than or equal to 0.5% of the mass of the silicon nitride powder, and the mass of the penetrant is greater than or equal to 0.5% of the mass of the silicon nitride powder, the yield rate of the silicon nitride green body is further improved.
[0117] 4. Comparing Example 1 and Example 6, it can be seen that when the tape casting process is carried out in a solvent atmosphere, the cracking rate of the obtained silicon nitride green body is further reduced and the yield rate is further improved;
[0118] 5. By comparing Example 1 and Example 8, it can be seen that when the order of adding the raw materials is limited and the preparation method is prepared by two ball milling processes, the yield rate of the obtained silicon nitride green body is further improved.
[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.
Claims
1. A silicon nitride green body, characterized in that: include: Silicon nitride powder, a penetrant, and a wetting agent, wherein the penetrant includes at least one of fatty alcohol polyoxyethylene ether and nonylphenol polyoxyethylene ether, and the wetting agent includes at least one of triolein, monoolein, and fatty acid polyoxyethylene ester, wherein the total mass of the wetting agent and the penetrant is greater than or equal to 1% of the mass of the silicon nitride powder.
2. The silicon nitride green body according to claim 1, characterized in that The total mass of the wetting agent and the penetrant is less than or equal to 3% of the mass of the silicon nitride powder; and / or, The mass of the wetting agent is greater than or equal to 0.5% of the mass of the silicon nitride powder, and the mass of the penetrant is greater than or equal to 0.5% of the mass of the silicon nitride powder.
3. The silicon nitride green body according to claim 1 or 2, characterized in that: The silicon nitride green body further includes a dispersant, a binder, a plasticizer, a sintering aid, and an organosilicon degassing agent, and the mass ratio of the silicon nitride powder, the penetrant, the dispersant, the binder, the wetting agent, the plasticizer, the sintering aid, and the organosilicon degassing agent is 100:(0.2-1):(2-4):(5-10):(0.2-1):(5-7):(5-7):(1-2).
4. The silicon nitride green body according to any one of claims 1 to 3, characterized in that: The D50 of the silicon nitride powder is 0.5-1 μm; and / or, The dispersant includes at least one of triethyl phosphate, polyacrylamide, and polyethylene glycol; and / or The adhesive comprises at least one of polyvinyl butyral, polyvinyl chloride, polyvinyl alcohol, and polymethacrylate; and / or The plasticizer includes at least one of polyethylene glycol, dioctyl oxalate, dioctyl phthalate, and dibutyl phthalate; and / or The sintering aid includes at least two of magnesium oxide, yttrium oxide, and calcium oxide; and / or, The organic silicon defoaming agent includes at least one of dimethylsiloxane, dimethylsilane and polysiloxane; and / or, The thickness of the silicon nitride green body is 0.3-1 mm.
5. A method for preparing a silicon nitride green body according to any one of claims 1 to 4, characterized in that: The following steps are involved: A mixed solution including the silicon nitride powder, the penetrant and the wetting agent is ball-milled to obtain a raw material slurry, and the raw material slurry is subjected to a tape casting process to obtain a silicon nitride green body.
6. The preparation method according to claim 5, characterized in that Before the tape casting process, the following steps are included: 1) ball milling a first mixed solution comprising silicon nitride powder, a sintering aid, a dispersant, a penetrant, and a first solvent to obtain a first slurry; 2) adding a second mixed solution comprising a plasticizer, a binder, a wetting agent, and a second solvent to the first slurry and performing secondary ball milling to obtain a second slurry; 3) adding an organosilicon degassing agent to the second slurry for vacuum degassing to obtain the raw material slurry.
7. The preparation method according to claim 6, characterized in that In the primary ball milling and / or secondary ball milling, the ball milling medium is silicon nitride balls with a particle size of 3 to 5 mm, and the rotation speed is 150 to 200 r / min; and / or, The vacuum degassing comprises: -2 ~10 -1 Pa vacuum degassing to obtain a raw material slurry with a viscosity of 2000-8000 mPa·s; and / or, The first solvent and the second solvent include an alcohol solvent and a benzene-ketone mixed solvent in a mass ratio of 1:(1-10); and / or, The total mass of the first solvent and the second solvent is 60-100% of the mass of the silicon nitride powder.
8. The preparation method according to any one of claims 5 to 7, characterized in that The tape casting process is performed in a solvent atmosphere.
9. A silicon nitride ceramic substrate, characterized in that: The silicon nitride green body is prepared from the silicon nitride green body according to any one of claims 1 to 4, or the silicon nitride green body prepared by the preparation method according to any one of claims 5 to 8.
10. A semiconductor device, characterized in that: The method comprises the silicon nitride ceramic substrate according to claim 9 and a semiconductor layer provided on the silicon nitride ceramic substrate.