Die attach film and memory chip, and preparation methods therefor

Abstract

Provided in the present invention are a die attach film and a memory chip, and preparation methods therefor. The die attach film comprises the following components in parts by mass: 20-30 parts of silicon dioxide, 20-25 parts of a rubber-modified epoxy resin, 10-15 parts of an acrylic epoxy resin, 10-20 parts of a flexible epoxy resin, 15-20 parts of a polyurethane-modified epoxy resin, 20-25 parts of a curing agent, and 0.5-1.0 part of a promoter, wherein the flexible epoxy resin is YX-7400. By adjusting the ratio of the rubber-modified epoxy resin to the acrylic epoxy resin to the flexible epoxy resin to the polyurethane-modified epoxy resin, and under the action of the promoter, the curing agent and the mixed epoxy resins are cross-linked to form a whole. Moreover, the internal stress and thermal expansion coefficient of the die attach film are reduced by means of silicon dioxide, and therefore the die attach film has an ultra-low modulus, a high adhesive force and low water absorption. During the packaging process of a chip, the die attach film is in a molten state at a high temperature and comes into close contact with the chip, thereby improving the packaging yield of a chip.

Description

Wafer bonding film, memory chip and preparation method thereof TECHNICAL FIELD

[0001] The present application belongs to the technical field of chip packaging, and particularly relates to a wafer bonding film, a memory chip and a preparation method thereof. BACKGROUND

[0002] The wafer bonding film is a key material commonly used in the chip packaging process. The wafer bonding film is used for laser cutting in the chip packaging process, so that the wafers can be cut and separated together, peeled off, and the cut wafers still adhere to the film and will not be scattered due to cutting. At the same time, the wafer bonding film can bond chips or substrates on both sides to realize multi-chip packaging. At present, it is difficult to control the air bubbles during the bonding of large-size chips, and cavities are easily formed after curing, thereby affecting the packaging yield of the chips.

[0003] Therefore, how to provide a wafer bonding film, by adjusting the proportion of rubber modified epoxy resin, acrylic epoxy resin, flexible epoxy resin and polyurethane modified epoxy resin, to reduce the storage modulus and water absorption of the wafer bonding film, and thereby improve the packaging yield of the chip, is a technical problem that the person skilled in the art needs to solve. SUMMARY

[0004] The present application aims to provide a wafer bonding film, a memory chip and a preparation method thereof to at least solve the above-mentioned technical problem.

[0005] To achieve the above-mentioned purpose, the present application provides a wafer bonding film in the first aspect, which comprises the following components in mass fraction: 20-30 parts of silica, 20-25 parts of rubber modified epoxy resin, 10-15 parts of acrylic epoxy resin, 10-20 parts of flexible epoxy resin, 15-20 parts of polyurethane modified epoxy resin, 20-25 parts of curing agent, and 0.5-1.0 parts of accelerator; the flexible epoxy resin is YX-7400.

[0006] In the first aspect, the silica is spherical silica, and the particle size D50 of the spherical silica is 0.6 microns.

[0007] In the first aspect, the curing agent is a phenolic curing agent; the phenolic curing agent includes a liquid curing agent and a solid curing agent.

[0008] In the first aspect, the liquid curing agent is MTH-8000, and the solid curing agent is YLOK aralkyl phenol resin.

[0009] In the first aspect, the accelerator is an imidazole compound.

[0010] In the first aspect, the rubber-modified epoxy resin is HyPox RK84L.

[0011] In the first aspect, the polyurethane-modified epoxy resin is EPU-133.

[0012] The second aspect of the present application provides a preparation method of the wafer bonding film as described in the first aspect, and the preparation method comprises:

[0013] S1, the components are stirred and mixed according to the respective mass fractions to obtain a first slurry; the mass fractions of the components specifically include: 20-30 parts of silicon dioxide, 20-25 parts of rubber-modified epoxy resin, 10-15 parts of acrylic epoxy resin, 10-20 parts of flexible epoxy resin, 15-20 parts of polyurethane-modified epoxy resin, 20-25 parts of curing agent, and 0.5-1.0 parts of accelerator; the flexible epoxy resin is YX-7400;

[0014] S2, the first slurry is transferred to a bead mill for grinding to obtain a uniform second slurry;

[0015] S3, the second slurry is vacuum degassed to obtain a third slurry;

[0016] S4, the third slurry is coated by a coating machine and baked;

[0017] S5, after baking, a wafer bonding film is obtained.

[0018] The third aspect of the present application provides a preparation method of a memory chip, and the preparation method comprises: obtaining a memory chip body; pasting a wafer bonding film on the surface of the memory chip body to obtain a pre-packaged chip; the wafer bonding film is made by the preparation method of the wafer bonding film as described in the second aspect; cutting, chip bonding, and wire bonding are performed on the pre-packaged chip to obtain a chip whole; pressure curing is performed on the chip whole to obtain a packaged memory chip; the conditions of the pressure curing include: a pressure of 0.8 MPa, a temperature of 175℃, and a time of 4h.

[0019] The fourth aspect of the present application provides a memory chip, which is made by the preparation method of the memory chip as described in the third aspect. Advantages:

[0020] The wafer bonding film comprises the following components in mass parts: 20-30 parts of silica, 20-25 parts of rubber modified epoxy resin, 10-15 parts of acrylic epoxy resin, 10-20 parts of flexible epoxy resin, 15-20 parts of polyurethane modified epoxy resin, 20-25 parts of curing agent, and 0.5-1.0 parts of accelerator; the flexible epoxy resin is YX-7400; the film-forming property of the rubber modified epoxy resin, the water absorption of the acrylic epoxy resin, the resilience of the flexible epoxy resin and the adhesion of the polyurethane modified epoxy resin are adjusted by adjusting the proportion among the four, to form a mixed epoxy resin, under the action of the accelerator, the curing agent and the mixed epoxy resin are crosslinked to form a whole, so that the wafer bonding film has high adhesion and low modulus, and the internal stress and the thermal expansion coefficient of the wafer bonding film are reduced by the silica, so that the wafer bonding film is in a molten state at high temperature during the chip packaging process, can be in close contact with the chip, and the packaging yield of the chip is improved. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present specification or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0022] Fig. 1 is a flow chart of a preparation method of a wafer bonding film according to the present application. DETAILED DESCRIPTION

[0023] The advantages and various effects of the present application will be more clearly presented by the following specific embodiments and examples. Those skilled in the art should understand that these specific embodiments and examples are used to illustrate the present application, not to limit the present application.

[0024] Throughout the specification, unless otherwise specifically indicated, the terms used herein are to be understood as having the meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as generally understood by those skilled in the art to which the present application belongs. If there is a contradiction, the present specification is preferred.

[0025] Unless otherwise specifically indicated, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or obtained by existing methods.

[0026] The wafer bonding film provided by the application comprises the following components in mass parts: 20-30 parts of silica, 20-25 parts of rubber modified epoxy resin, 10-15 parts of acrylic epoxy resin, 10-20 parts of flexible epoxy resin, 15-20 parts of polyurethane modified epoxy resin, 20-25 parts of curing agent, and 0.5-1.0 parts of accelerator; the flexible epoxy resin is YX-7400.

[0027] Specifically, the wafer bonding film provided by the application comprises the following components in mass parts: 20-30 parts of silica, 20-25 parts of rubber modified epoxy resin, 10-15 parts of acrylic epoxy resin, 10-20 parts of flexible epoxy resin, 15-20 parts of polyurethane modified epoxy resin, 20-25 parts of curing agent, and 0.5-1.0 parts of accelerator; the flexible epoxy resin is YX-7400; the film-forming property of the rubber modified epoxy resin, the water absorption of the acrylic epoxy resin, the resilience of the flexible epoxy resin, and the adhesion of the polyurethane modified epoxy resin are adjusted to form a mixed epoxy resin, and under the action of the accelerator, the curing agent and the mixed epoxy resin are crosslinked to form an integral whole, so that the wafer bonding film has high adhesion and low modulus, and the internal stress and the coefficient of thermal expansion of the wafer bonding film are reduced by the silica, so that the wafer bonding film is in a molten state at high temperature during the chip packaging process, can be in close contact with the chip, and the packaging yield of the chip is improved.

[0028] In some possible embodiments, the silica is spherical silica, and the particle size D50 of the spherical silica is 0.6 microns.

[0029] This is because, by using spherical silica as the filling material, agglomeration can be avoided during the melting process, thereby affecting the fluidity of the wafer bonding film glue solution in the molten state, and the storage modulus and the coefficient of thermal expansion of the wafer bonding film can also be adjusted to improve the packaging yield of the chip.

[0030] In some possible embodiments, the curing agent is a phenolic curing agent; the phenolic curing agent comprises a liquid curing agent and a solid curing agent.

[0031] In some possible embodiments, the liquid curing agent is MTH-8000, and the solid curing agent is YLOK aralkyl phenol resin.

[0032] The skilled in the art can understand that the YLOK aralkyl phenol resin used as the solid curing agent in the present application can not only react with the epoxy resin, but also improve the adhesion of the wafer bonding film. Furthermore, the MTH-8000 used as the liquid curing agent can increase the contact area with the epoxy resin. By adjusting the ratio of the solid curing agent and the liquid curing agent, the reaction efficiency of the wafer bonding film in the melting and curing process can be controlled.

[0033] In some possible embodiments, the accelerator is an imidazole compound.

[0034] The accelerator can accelerate the reaction rate of the epoxy resin and the curing agent at a certain temperature, reduce the curing time, and improve the production efficiency.

[0035] In some possible embodiments, the rubber-modified epoxy resin is HyPox RK84L.

[0036] The epoxy equivalent of the HyPox RK84L epoxy resin is 1250-1500 g / eq, and the HyPox RK84L epoxy resin has high toughness and elasticity. By adjusting the proportion of the HyPox RK84L, the tensile strength of the wafer bonding film can be controlled.

[0037] In some possible embodiments, the polyurethane-modified epoxy resin is EPU-133.

[0038] The epoxy equivalent of the polyurethane-modified epoxy resin EPU-133 is 230 g / eq. By adjusting the proportion of the EPU-133, the viscosity of the wafer bonding film can be adjusted, and the adhesion between the wafer bonding film and the chip can be improved, thereby improving the packaging yield of the chip.

[0039] Based on the overall inventive concept, referring to FIG. 1, the present application further provides a preparation method of the wafer bonding film according to the first aspect, and the preparation method comprises the following steps:

[0040] S1, stirring and mixing components according to respective mass fractions to obtain a first slurry; the mass fractions of the components specifically include: 20-30 parts of silica, 20-25 parts of rubber-modified epoxy resin, 10-15 parts of acrylic epoxy resin, 10-20 parts of flexible epoxy resin, 15-20 parts of polyurethane-modified epoxy resin, 20-25 parts of curing agent, and 0.5-1.0 parts of accelerator; the flexible epoxy resin is YX-7400;

[0041] S2, transferring the first slurry to a bead mill for grinding to obtain a uniform second slurry;

[0042] S3, vacuum debubbling the second slurry to obtain a third slurry;

[0043] S4, the third slurry is coated by a coating machine and baked;

[0044] S5, after the baking is finished, a wafer bonding film is obtained.

[0045] The preparation method of the wafer bonding film is simple and easy to operate, the slurry after coating is baked in a programmed temperature rising mode to remove the solvent, and the wafer bonding film with uniform thickness and no hole is obtained.

[0046] Based on one general inventive concept, a preparation method of a memory chip comprises:

[0047] (1) obtaining a memory chip body;

[0048] (2) pasting a wafer bonding film on the surface of the memory chip body to obtain a pre-packaged chip; the wafer bonding film is made by the preparation method of the wafer bonding film in the second aspect;

[0049] (3) cutting, chip bonding and wire bonding the pre-packaged chip to obtain a chip whole;

[0050] (4) pressure curing the chip whole to obtain a packaged memory chip; the pressure curing condition comprises: a pressure of 0.8 MPa, a temperature of 175 ℃ and a time of 4 h.

[0051] Those skilled in the art can understand that the wafer bonding film prepared according to the formula proportion in the first aspect has a certain bonding property, can be attached to the surface of the chip body, and can preliminarily package the chip body, then the chip whole with a proper size is obtained through cutting, chip bonding and wire bonding, and the chip whole is pressure cured under the condition of a pressure of 0.8 MPa and a temperature of 175 ℃, so that the wafer bonding film is in a molten state under the condition, so as to discharge the air bubbles between the wafer bonding film and the chip, and after 4 h, the pressure and the temperature are removed, and the packaged memory chip is obtained.

[0052] Based on one general inventive concept, the application further provides a memory chip made by the preparation method of the memory chip in the third aspect.

[0053] The application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the application and not to limit the scope of the application. The experimental methods not specified in the following examples are generally determined according to the national standards. If there is no corresponding national standard, the international standard, the conventional condition or the condition suggested by the manufacturer is used.

[0054] The components of the raw materials in Comparative Examples 1-9 and Example 1-7 are shown in Table 1-2 below in terms of mass parts:

[0055] Table 1: Proportioning of raw material components in Comparative Examples

[0056] Table 2: Proportioning of raw material components in Examples

[0057] After curing the wafer adhesive films provided in Examples 1-7 and Comparative Examples 1-9, the storage modulus, temperature / constant temperature rheology, moisture absorption rate, and silicon wafer adhesion tests were performed, and the specific test processes are as follows:

[0058] 1. Cured storage modulus test: reference standard: ASTM E2254-2018, take the sample cured completely at 175℃ / 1h, prepare the test sample with a size of 25mm×6.5mm×0.25mm, measurement mode: Tension: Film, heat up to 250℃ at a rate of 5℃ / min, take the storage modulus at 25℃ and 200℃;

[0059] 2. Temperature rheology test: the sample is made into a circular sheet with a thickness of 1mm and a diameter of 20mm. Test mode: Oscillation Temperature Ramp, temperature rising program: 25℃ to 200℃, heating rate: 5℃ / min;

[0060] 3. Constant temperature rheology test: the sample is made into a circular sheet with a thickness of 1mm and a diameter of 20mm. Test mode: Oscillation Temperature Ramp, program: 25℃ to 165℃, then constant temperature at 165℃ for 4H, heating rate: 5℃ / min

[0061] 4. Moisture absorption rate test: take 50mm×50mm film material and transfer it to a silicon wafer, weigh after curing at 175℃ for 1h. Then immerse the silicon wafer vertically in a glass container containing 25±1℃ distilled water, the surface should not have air bubbles and should not be in contact with the container wall. After 24h of immersion, remove it with tweezers, quickly absorb the water on the film surface with filter paper, and immediately weigh.

[0062] 5. Silicon wafer adhesion: transfer a 2mm×2mm film with a thickness of 25μm to a silicon wafer with a size of 10mm×10mm, then cover it with a 2mm×2mm silicon wafer and clamp it with a clamp, after curing at 175℃ for 1h, test the shear bonding strength at 25℃ and 260℃ with a multifunctional shear force tester.

[0063] The test results are shown in Table 3 below:

[0064] Table 3: Test results

[0065] From the above table, it can be seen that the wafer bonding film added with acrylic epoxy resin has lower water absorption and storage modulus; the wafer bonding film prepared by using YX-7400 flexible epoxy resin has lower storage modulus and higher silicon wafer adhesion; the wafer bonding film prepared according to the formulation proportion of the present application has ultralow storage modulus, low moisture absorption and high silicon wafer adhesion; in the process of temperature curing, the rheological viscosity of the wafer bonding film gradually increases, and through the data of the rheological viscosity at the temperature rising and the constant temperature, it can be seen that the change gap of the rheological viscosity of the wafer bonding film prepared by using examples 1-7 is smaller than that of the film prepared by using comparative examples 1-9, it can be understood that the wafer bonding film of the present application has better stability, the wafer bonding film after baking is pasted on the surface of the chip, and the chip is cut, bonded, wire bonded, and pressure cured, so that the wafer bonding film is in a molten state at high temperature, so as to discharge the air bubbles between the chip and the wafer bonding film, and then improve the packaging yield of the chip.

[0066] Finally, it should be noted that the terms "comprising", "including", or any other variant thereof are intended to cover non-exclusive inclusions, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such process, method, article or equipment.

[0067] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to the embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0068] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A wafer bonding film, characterized by, The wafer bonding film comprises the following components in mass fraction: 20-30 parts of silica, 20-25 parts of rubber modified epoxy resin, 10-15 parts of acrylic epoxy resin, 10-20 parts of flexible epoxy resin, 15-20 parts of polyurethane modified epoxy resin, 20-25 parts of curing agent, and 0.5-1.0 parts of accelerator; the flexible epoxy resin is YX-7400; The curing agent is a phenolic curing agent; the phenolic curing agent comprises a liquid curing agent and a solid curing agent; The liquid curing agent is MTH-8000; the solid curing agent is YLOK aralkyl phenolic resin; The rubber modified epoxy resin is HyPox RK84L; The polyurethane modified epoxy resin is EPU-133.

2. The wafer bonding film of claim 1, wherein The silica is spherical silica, and the particle size D50 of the spherical silica is 0.6 μm.

3. The wafer bonding film of claim 2, wherein The accelerator is an imidazole compound.

4. A method of producing a wafer bonding film according to any one of claims 1 to 3, characterized by, The preparation method comprises: S1, stirring and mixing the components according to their respective mass fractions to obtain a first slurry; the mass fractions of the components specifically comprise: 20-30 parts of silica, 20-25 parts of rubber modified epoxy resin, 10-15 parts of acrylic epoxy resin, 10-20 parts of flexible epoxy resin, 15-20 parts of polyurethane modified epoxy resin, 20-25 parts of curing agent, and 0.5-1.0 parts of accelerator; the flexible epoxy resin is YX-7400; S2, transferring the first slurry to a bead mill for grinding to obtain a uniform second slurry; S3, vacuum debubbling the second slurry to obtain a third slurry; S4, coating the third slurry by a coating machine and baking; S5, obtaining a wafer bonding film after the baking is completed.

5. A method of fabricating a memory chip, characterized by, The preparation method comprises: obtaining a memory chip body; attaching a wafer bonding film to the surface of the memory chip body to obtain a pre-packaged chip; the wafer bonding film is made by the preparation method of the wafer bonding film according to claim 4; cutting, chip bonding, and wire bonding the pre-packaged chip to obtain a chip whole; pressure curing the chip whole to obtain a packaged memory chip; the pressure curing conditions comprise a pressure of 0.8 MPa, a temperature of 175 ℃, and a time of 4 h.

6. A memory chip, characterized by The memory chip is made by the preparation method of the memory chip according to claim 5.

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