Sintered metal material and preparation method and application thereof

Abstract

The invention discloses a sintered metal material and a preparation method and application thereof, and relates to the technical field of power semiconductor connection, and the sintered metal material is prepared from, by mass, 30%-95% of first metal powder, 0.01%-1% of microsphere powder, 5%-70% of organic solvent, 0-10% of dispersing agent and 0-30% of auxiliary materials. According to the sintered metal material provided by the invention, the microsphere powder with an interface thickness supporting effect is added, so that after the sintered metal material is subjected to pressure sintering or hot pressing to form the metal layer, the thickness of the metal layer is controlled, and the uniformity of the thickness of the metal layer is ensured.

Description

Technical Field

[0001] This invention relates to the field of power semiconductor interconnect technology, and in particular to a sintered metal material, its preparation method, and its application. Background Technology

[0002] Power semiconductor chips are semiconductor devices specifically designed for handling and controlling high voltage and high current. By applying external control signals (such as voltage and current), the electric field distribution of the semiconductor material inside the chip is altered, thereby controlling its on / off state and achieving precise regulation of the power flow in the main circuit. Common power semiconductor chips include wide-bandgap semiconductor chips, silicon-based IGBT chips, and silicon-based MOSFET chips. In the single-pass sintering process of the metal layer on power semiconductor chips, embedded packaging places extremely high demands on the consistency of each chip. Existing hot-pressing sintering processes for metal materials may result in uneven metal layer thickness during a single pass. Summary of the Invention

[0003] The main objective of this invention is to propose a sintered metal material, its preparation method, and its application, aiming to solve the problem of uneven metal layer thickness that may occur during the single sintering process of existing hot-pressed sintered metal materials.

[0004] To achieve the above objectives, the sintered metal material proposed in this invention is made from raw materials comprising the following components by weight percentage: The composition includes 30%~95% first metal powder, 0.01%~1% microsphere powder, 5%~70% organic solvent, 0~10% dispersant, and 0~30% excipients; The first metal powder includes one or more of copper powder, silver powder, gold powder, and nickel powder; Microsphere powder includes one or more of glass powder, ceramic powder, and second metal powder.

[0005] Preferably, the metal powder includes one or more of the following: nano-spherical powder, micron-sized flake powder, micron-sized spherical powder, submicron-sized spherical powder, and submicron-sized flake powder.

[0006] Preferably, the particle size of the microsphere powder is 10~500μm; The ceramic powder includes one or more of the following: zirconium oxide powder, silicon carbide powder, alumina powder, silicon nitride powder, aluminum nitride powder, and diamond powder. The second metal powder includes one or more of stainless steel powder and nickel powder.

[0007] Preferably, the organic solvent includes one or more of alcohols, esters, ethers, carboxylic acids, and organic amines.

[0008] Preferably, the organic solvent includes terpineol, ethanol, isopropanol, butanol, ethylene glycol, polyethylene glycol, diethylene glycol, triethylene glycol, glycerol, 1,3-butanediol, 1,2-pentanediol, sorbitol, 1,9-nonanediol, tricyclodecanediethanol, propylene glycol, pentaerythritol, ethyl acetate, butyl acetate, diethylene glycol butyl ether acetate, butyl solvent anhydride acetate, diethyl phthalate, ethyl propionate, and ethyl butyrate. Diethyl adipate, ethyl benzoate, diethyl maleate, ethylene glycol ethyl ether, propylene glycol methyl ether, diethylene glycol butyl ether, triethylene glycol monomethyl ether, tetrahydrofuran, ethyl ether, isopropyl ether, dipropylene glycol methyl ether, formic acid, acetic acid, caprylic acid, caprylic acid, valeric acid, heptanoic acid, hexanoic acid, nonanoic acid, citric acid, ascorbic acid, triethanolamine, cyclohexylamine, aniline, ethylenediamine, isopropylamine, octadecylamine, N,N-dimethylethanolamine, or one or more of these.

[0009] Preferably, the dispersant comprises one or more of polyethylene glycol, stearic acid, polyvinylpyrrolidone, triethanolamine, polycarboxylate compounds, organosilicon compounds, silane coupling agents, titanate coupling agents, polyether-modified silicone oil, nano-silica, fumed silica, polyurethane compounds, polycarboxylate compounds, polyether compounds, sodium alkylbenzene sulfonate, acrylate copolymers, quaternary ammonium compounds, and sodium dodecylbenzene sulfonate.

[0010] Preferably, the excipients include one or more of the following: rosin resin, organic acid compounds, epoxy resin, polyurethane, acrylic resin, alkyd resin, cellulose, and polyamide compounds.

[0011] The present invention also proposes a method for preparing the sintered metal material proposed in the present invention, the method comprising: weighing the raw materials according to the mass percentage and mixing them to obtain the sintered metal material.

[0012] This invention also proposes the application of the sintered metal material proposed in this invention and the preparation method of the sintered metal material proposed in this invention in the preparation of power semiconductor chips.

[0013] Preferably, the sintered metal material is used to prepare a metal layer on the top electrode of a power semiconductor chip.

[0014] The sintered metal material provided by the present invention comprises, by mass percentage, 30%~95% first metal powder, 0.01%~1% microsphere powder, 5%~70% organic solvent, 0%~10% dispersant, and 0%~30% auxiliary materials. The manufacturing process is simple, environmentally friendly, and low-cost. Furthermore, by adding microsphere powder to the sintered metal material, the microsphere powder plays a supporting role in the interface thickness. When the sintered metal material is coated onto the top electrode of a power semiconductor chip and a metal layer is formed after pressure sintering or hot pressing, the microsphere powder helps to limit excessive collapse of the metal layer under pressure, thereby controlling the thickness of the metal layer and ensuring its uniformity. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the process for forming a metal layer by pressure sintering of sintered metal materials provided by the present invention.

[0017] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0020] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0021] In the single-pass sintering process of metal layers on power semiconductor chips, embedded packaging has extremely high requirements for the consistency of each chip. Existing hot-pressed sintered metal materials may have uneven metal layer thickness during the single-pass sintering process.

[0022] Based on this, the present invention proposes a sintered metal material, which, by mass percentage, is made from raw materials comprising the following components: The composition consists of 30% to 95% metal powder, 0.01% to 1% microsphere powder, 5% to 70% organic solvent, 0% to 10% dispersant, and 0% to 30% excipients.

[0023] The mass percentage of the first metal powder can be 30%, 40%, 45%, 50%, 60%, 70%, 80%, 90%, or 95%, etc. The first metal powder includes one or more of copper powder, silver powder, gold powder, and nickel powder. The first metal powder is the core functional phase of the sintered metal material, determining the basic properties of the metal layer after sintering. After sintering, the metal particles in the first metal powder interconnect and fuse to form a dense conductive network, providing electrical connection channels for the chip. Simultaneously, the first metal powder also acts as a thermal conductor, efficiently conducting the heat generated during chip operation. Furthermore, the metal layer formed after sintering of the first metal powder has high mechanical strength, enabling it to fix the chip to the substrate. Preferably, the mass percentage of the first metal powder is 60-85%.

[0024] In some embodiments, the first metal powder includes one or more of nano-spherical powder, micron-sized flake powder, micron-sized spherical powder, submicron-sized spherical powder, and submicron-sized flake powder.

[0025] The mass percentage of microsphere powder can be 0.01%, 0.05%, 0.1%, 0.2%, 0.5%, 0.7%, 0.9%, or 1%, etc. Microsphere powder plays a role in supporting the interface thickness in sintered metal materials. For example... Figure 1 As shown, when sintered metal material is coated on the top electrode of a power semiconductor chip, a metal layer is formed after pressure sintering or hot pressing. The microsphere powder plays a role in limiting the excessive collapse of the metal layer under pressure, thereby achieving control over the thickness of the metal layer.

[0026] In some embodiments, the microsphere powder includes one or more of glass powder, ceramic powder, and a second metal powder. Preferably, the ceramic powder includes one or more of zirconium oxide powder, silicon carbide powder, alumina powder, silicon nitride powder, aluminum nitride powder, and diamond powder, and the second metal powder includes one or more of stainless steel powder and nickel powder. Glass powder, ceramic powder, and the second metal powder have the characteristics of high melting point, high hardness, uniform size dispersion, and high consistency. Therefore, when the sintered metal material undergoes pressure sintering or hot pressing, the morphology of the microsphere powder can be maintained, achieving control over the thickness of the formed metal layer. The particle size of the microsphere powder is 10~500 μm, for example, the particle size of the microsphere powder can be 10 μm, 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, or 500 μm, etc.

[0027] For example, when the hot-pressing shrinkage rate of sintered metal material is about 70%, by incorporating microsphere powder with a diameter of 30 μm into the sintered metal material, when the coating thickness of the sintered metal material is 100 μm, the thickness of the metal layer formed after pressure sintering of the sintered metal material can be about 30 μm.

[0028] The mass percentage of the organic solvent can be 4.99%, 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 69.99%, or 70%, etc. In some embodiments, the organic solvent includes terpineol, ethanol, isopropanol, butanol, ethylene glycol, polyethylene glycol, diethylene glycol, triethylene glycol, glycerol, 1,3-butanediol, 1,2-pentanediol, sorbitol, 1,9-nonanediol, tricyclodecanediol, propylene glycol, pentaerythritol, ethyl acetate, butyl acetate, diethylene glycol butyl ether acetate, butyl solvent anhydride acetate, diethyl phthalate, ethyl propionate, and ethyl butyrate. One or more of the following: diethyl adipate, ethyl benzoate, diethyl maleate, ethylene glycol ethyl ether, propylene glycol methyl ether, diethylene glycol butyl ether, triethylene glycol monomethyl ether, tetrahydrofuran, ethyl ether, isopropyl ether, dipropylene glycol methyl ether, formic acid, acetic acid, octanoic acid, caprylic acid, octanoic acid, valeric acid, heptanoic acid, hexanoic acid, nonanoic acid, citric acid, ascorbic acid, triethanolamine, cyclohexylamine, aniline, ethylenediamine, isopropylamine, octadecylamine, and N,N-dimethylethanolamine. Organic solvents, acting as carriers and flow modifiers, ensure uniform mixing and dispersion of the first metal powder and other components, forming a stable and homogeneous slurry. They also adjust the viscosity and thixotropy of the slurry.

[0029] The mass percentage of the dispersant can be 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, etc. In some embodiments, the dispersant includes one or more of polyethylene glycol, stearic acid, polyvinylpyrrolidone, triethanolamine, polycarboxylate compounds, organosilicon compounds, silane coupling agents, titanate coupling agents, polyether-modified silicone oil, nano-silica, fumed silica, polyurethane compounds, polycarboxylate compounds, polyether compounds, sodium alkylbenzene sulfonate, acrylate copolymers, quaternary ammonium salt compounds, and sodium dodecylbenzene sulfonate. The dispersant can be adsorbed on the surface of components such as the first metal powder and microsphere powder, and through electrostatic repulsion or steric hindrance, the particles are separated from each other and stably suspended in the solvent, thereby preventing the agglomeration of the first metal powder and microsphere powder; at the same time, it can also maintain the homogeneity of the sintered metal material.

[0030] The mass percentage of excipients can be 0%, 5%, 10%, 15%, 20%, 25%, or 30%, etc. In some embodiments, excipients include one or more of rosin resin, organic acid compounds, epoxy resin, polyurethane, acrylic resin, alkyd resin, cellulose, and polyamide compounds.

[0031] The present invention also proposes a method for preparing the sintered metal material as described above, comprising the steps of: weighing raw materials by mass percentage and mixing them to obtain the sintered metal material.

[0032] Specifically, the raw materials include the following components: 30%~95% first metal powder, 0.01%~1% microsphere powder, 5%~70% organic solvent, 0~10% dispersant, and 0~30% excipients. Each component adopts all the technical solutions of all the above embodiments, and therefore has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0033] In some embodiments, the mixing method includes one or more of ultrasonication, high-shear dispersion, ball milling, degassing stirring, and mechanical stirring. For example, one or more of ball mills, degassing mixers, mechanical mixers, three-roll mills, vacuum mixers, ribbon mixers, conical mixers, and double-cone mixers can be used for thorough mixing.

[0034] The present invention also proposes the application of the sintered metal material and the preparation method of the sintered metal material as described above in the preparation of power semiconductor chips.

[0035] In some embodiments, sintered metal materials are used to prepare a power semiconductor chip or a metal layer on the top electrode of a power semiconductor chip wafer.

[0036] The following examples provide further illustration.

[0037] Example 1 The raw materials were weighed in half the following proportions by weight: 65% micron-sized copper powder, 1% zirconium oxide powder (30 μm), 32% isopropanol, 1% ethylene glycol, and 1% rosin resin. The raw materials were placed in a double hammer mixer and stirred to obtain sintered metal materials.

[0038] Example 2 The raw materials were weighed in half the following proportions: 95% nano silver powder, 0.01% stainless steel powder (50 μm), and 4.99% butyl solvent anhydride acetate. The raw materials were placed in a ribbon mixer and stirred to obtain sintered metal materials.

[0039] Example 3 The raw materials are weighed in half the following proportions by weight: 30% nickel powder (micron-sized flake powder), 1% glass powder (60 μm), 60% triethylene glycol monomethyl ether, 4% silane coupling agent, and 5% epoxy resin. The raw materials are placed in a conical mixer and stirred to obtain sintered metal materials.

[0040] Example 4 The raw materials were weighed in half the following mass ratio: 30% nano gold powder, 0.01% silicon carbide powder (100 μm), and 69.99% acetic acid. The raw materials were placed in a double hammer mixer and stirred to obtain sintered metal materials.

[0041] Example 5 The raw materials are weighed in half the following proportions by weight: 30% nano copper powder, 1% zirconium oxide powder (20 μm), 30% isopropanol, 10% ethylene glycol, and 30% rosin resin. The raw materials are placed in a double hammer mixer and stirred to obtain sintered metal materials.

[0042] Example 6 The raw materials were weighed in half the following mass ratio: 60% nano copper powder, 0.01% silicon carbide powder (10 μm), and 39.99% acetic acid. The raw materials were placed in a double hammer mixer and stirred to obtain sintered metal materials.

[0043] Example 7 The raw materials were weighed in half the following proportions by weight: 85% submicron copper powder, 1% zirconium oxide powder (300 μm), 12% isopropanol, 1% ethylene glycol, and 1% rosin resin. The raw materials were placed in a double hammer mixer and stirred to obtain sintered metal materials.

[0044] Example 8 The raw materials were weighed in half the following mass ratio: 70% nano copper powder, 0.01% silicon carbide powder (500 μm), and 29.99% acetic acid. The raw materials were placed in a double hammer mixer and stirred to obtain sintered metal materials.

[0045] The sintered metal material prepared in Example 1 was coated onto the bottom electrode of a power semiconductor chip using stencil printing, with a coating thickness of 100 μm. A copper sheet was then attached to the metal layer intermediate using a die-attachr. A Teflon film was placed on the surface of the power semiconductor chip wafer, followed by pressure sintering for 10 min at 25 MPa and 250°C in a mixed atmosphere of formic acid and nitrogen. The pressure-sintered power semiconductor chip wafer was then placed in a mixed atmosphere of formic acid and nitrogen and cooled to 30°C within 20 min, completing the preparation of the metal layer on the power semiconductor chip wafer. The prepared metal layer was tested, and its thickness was measured to be 30 μm.

[0046] In summary, the sintered metal material provided by this invention incorporates microsphere powder, which acts as a support for the interface thickness. When the sintered metal material is coated onto the top electrode of a power semiconductor chip and a metal layer is formed after pressure sintering or hot pressing, the microsphere powder helps to limit excessive collapse of the metal layer under pressure, thereby controlling the thickness of the metal layer and ensuring its uniformity.

[0047] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A sintered metal material, characterized in that, It is made from raw materials comprising the following components by weight percentage: The composition includes 30%~95% first metal powder, 0.01%~1% microsphere powder, 5%~70% organic solvent, 0~10% dispersant, and 0~30% excipients; The first metal powder includes one or more of copper powder, silver powder, gold powder, and nickel powder; Microsphere powder includes one or more of glass powder, ceramic powder, and second metal powder.

2. The sintered metal material as described in claim 1, characterized in that, The metal powder includes one or more of the following: nano-spherical powder, micron-sized flake powder, micron-sized spherical powder, submicron-sized spherical powder, and submicron-sized flake powder.

3. The sintered metal material as described in claim 1, characterized in that, The particle size of the microsphere powder is 10~500μm; The ceramic powder includes one or more of the following: zirconium oxide powder, silicon carbide powder, alumina powder, silicon nitride powder, aluminum nitride powder, and diamond powder. The second metal powder includes one or more of stainless steel powder and nickel powder.

4. The sintered metal material as described in claim 1, characterized in that, The organic solvent includes one or more of alcohols, esters, ethers, carboxylic acids, and organic amines.

5. The sintered metal material as described in claim 4, characterized in that, The organic solvents include terpineol, ethanol, isopropanol, butanol, ethylene glycol, polyethylene glycol, diethylene glycol, triethylene glycol, glycerol, 1,3-butanediol, 1,2-pentanediol, sorbitol, 1,9-nonanediol, tricyclodecanediethanol, propylene glycol, pentaerythritol, ethyl acetate, butyl acetate, diethylene glycol butyl ether acetate, butyl solvent anhydride acetate, diethyl phthalate, ethyl propionate, ethyl butyrate, and hexanediol. Diethyl benzoate, ethyl maleate, ethylene glycol ethyl ether, propylene glycol methyl ether, diethylene glycol butyl ether, triethylene glycol monomethyl ether, tetrahydrofuran, ethyl ether, isopropyl ether, dipropylene glycol methyl ether, formic acid, acetic acid, caprylic acid, capric acid, caprylic acid, valeric acid, heptanoic acid, hexanoic acid, nonanoic acid, citric acid, ascorbic acid, triethanolamine, cyclohexylamine, aniline, ethylenediamine, isopropylamine, octadecylamine, N,N-dimethylethanolamine, or one or more of these.

6. The sintered metal material as described in claim 1, characterized in that, The dispersant includes one or more of the following: polyethylene glycol, stearic acid, polyvinylpyrrolidone, triethanolamine, polycarboxylate compounds, organosilicon compounds, silane coupling agents, titanate coupling agents, polyether-modified silicone oil, nano-silica, fumed silica, polyurethane compounds, polycarboxylate compounds, polyether compounds, sodium alkylbenzene sulfonate, acrylate copolymers, quaternary ammonium compounds, and sodium dodecylbenzene sulfonate.

7. The sintered metal material as described in claim 1, characterized in that, The excipients include one or more of the following: rosin resin, organic acid compounds, epoxy resin, polyurethane, acrylic resin, alkyd resin, cellulose, and polyamide compounds.

8. A method for preparing a sintered metal material according to any one of claims 1 to 7, characterized in that, The preparation method includes: weighing the raw materials according to a mass percentage and mixing them to obtain the sintered metal material.

9. The application of the sintered metal material according to any one of claims 1 to 7 and the method for preparing the sintered metal material according to claim 8 in the preparation of power semiconductor chips.

10. The application as described in claim 9, characterized in that, The sintered metal material is used to prepare the metal layer on the top electrode of the power semiconductor chip.

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