Thin film material for semiconductor and preparation method thereof

Abstract

The invention provides a thin film material for a semiconductor and a preparation method of the thin film material. The thin film material is prepared from 78 to 82 parts of ethylene-vinyl acetate copolymer, 4.5 to 5.5 parts of cross-linking agent, 0.3 to 0.6 part of coupling agent, 0.8 to 3.2 parts of antioxidant, 0.02 to 0.05 part of flame retardant and 0.01 to 0.03 part of additive, grafting and crosslinking are carried out at the same time through irradiation, and the obtained EVA film material is good in compatibility, high in mechanical performance, good in heat dissipation performance and small in thermal deformation compared with a pure EVA film material; the obtained thin film is uniform in material property, still has good electrical insulation performance under the extremely thin material thickness, and is high in stability and applicable to many scenes.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor materials, and relates to a thin film material for semiconductors and a preparation method thereof. Background Art

[0002] With the development of semiconductor technology, miniaturization and high integration have become important trends in packaging; thin film materials can achieve more compact packaging designs and support high-density electrical connections. For example, thin film materials are widely used as packaging materials in advanced packaging technologies such as wafer-level packaging (WLP) and fan-out packaging (Fan-Out) to achieve chip miniaturization and high performance; for another example, in 2.5D / 3D packaging, thin film materials are used for interposers or redistribution layers (RDLs) to enable heterogeneous integration of multiple chips. This integration method can significantly improve the performance of chips while reducing power consumption. The above examples show that thin film materials are the key to realizing advanced packaging technologies.

[0003] However, some existing thin film materials have insufficient protection capabilities. For example, the physical and chemical protection performance of silicon chips used in fan-in WLCSP as packaging casings is relatively weak. During the packaging process, if the thickness of the thin film material is insufficient or there are defects, it may increase the risk of the chip being subjected to external physical impacts or chemical corrosion; or there may be a large difference in the thermal expansion coefficient from other packaging materials, such as the PCB substrate, and temperature changes during the packaging of the thin film material and the chip cause stress, which in turn affects the reliability of the packaging and the stability of the solder joints; or there are packaging size limitations and cost issues. For fan-in packaging, if the array size of the packaging solder balls is larger than the chip size, packaging cannot be carried out; in addition, when the number of chips on the wafer is small or the production yield is low, the cost of thin film packaging may be higher than that of traditional packaging; or there is insufficient heat dissipation. The heat dissipation performance of thin film materials is usually inferior to that of traditional heat dissipation materials such as metals or ceramics. In high-power chip packaging, thin film packaging may not be able to effectively dissipate the heat generated during chip operation, resulting in overheating of the chip.

[0004] In addition to the problems existing in the above packaging process, there are also some defects in the material selection of existing thin film packaging. For example:

[0005] ① In some advanced packaging technologies, the use of thin film materials may increase process complexity and costs. For example, the temporary bonding / debonding TBDB technology requires the use of special carrier wafers and adhesives, increasing the process steps and material costs.

[0006] ② Process complexity: Thin film packaging technologies, such as fan-out WLCSP, require complex processes such as re-wiring (RDL) and underfilling; these processes have high requirements for equipment accuracy and process control, increasing the production difficulty and costs.

[0007] ③Reliability issues: After replacing the traditional encapsulation materials, voids, delamination, and outgassing may occur during the thin-film encapsulation process; these defects will affect the reliability and electrical performance of the encapsulation and even lead to chip failures.

[0008] ④Material property limitation issues

[0009] Moisture absorption issues: Some thin-film materials, such as epoxy molding compounds, have certain moisture absorption, which may cause the inside of the encapsulation to get damp and affect the electrical performance of the chip.

[0010] Insufficient mechanical properties: The mechanical strength and toughness of thin-film materials are limited, and they are easily affected by mechanical stress during the encapsulation process, resulting in deformation or damage.

[0011] ⑤Environmental adaptability issues

[0012] Insufficient weather resistance: The weather resistance of thin-film materials, such as UV resistance and anti-aging, is usually poor, which may cause the performance of the encapsulation to decline during long-term use.

[0013] In summary, although thin-film materials have certain advantages in semiconductor encapsulation, there are also some disadvantages and limitations in practical applications. These disadvantages need to be overcome by optimizing material properties, improving process flows, and adopting more advanced encapsulation technologies.

[0014] With the increasing awareness of environmental protection, the selection of thin-film materials is also developing in a more environmentally friendly direction. For example, some new thin-film materials have biodegradability, reducing the impact on the environment. In summary, thin-film materials play an irreplaceable role in semiconductor encapsulation. Their functions such as physical protection, improvement of electrical performance, support for miniaturization, and heat dissipation management make them an indispensable part of modern semiconductor encapsulation technologies.

[0015] There is an urgent need in this field for a thin-film material with matching performance that can compensate for the property defects of the above-mentioned thin-film materials to meet the encapsulation requirements of semiconductor components. Summary of the Invention

[0016] Aiming at the disadvantages of the prior art, the present invention provides a thin-film material for semiconductors and a preparation method thereof.

[0017] To achieve the above object, the present invention adopts the following technical solutions:

[0018] A thin-film material for semiconductors, comprising a resin base material and a graft monomer. By weight, the resin base material comprises the following components:

[0019]

[0020] Preferably, the crosslinking agent comprises at least one of benzoyl peroxide and TAIC.

[0021] Preferably, the flame retardant is a mixture of organic nitrogen-based flame retardants and phosphorus-based flame retardants. Specifically, the flame retardant is a mixture of TPP and MCA.

[0022] Adopting the above technical solution, it has good compatibility, can significantly improve the flame retardant effect, and at the same time reduce the impact on the mechanical properties of the EVA material. Moreover, the graft monomers on the surface of the resin base can not only resist high-temperature degradation but also have good hydrophobicity, reduce the hygroscopicity of the mixed flame retardant itself, reduce the migration of the flame retardant and the ion dissociation of the material itself, and maintain long-term flame retardant effect and stable surface properties.

[0023] Preferably, the coupling agent includes at least one of isostearoyl titanate isopropyl ester TTS and aluminum distearoyl isopropylate.

[0024] Preferably, the auxiliary agent is silica and benzotriazole and its derivatives;

[0025] Furthermore, the auxiliary agent is nano-sized silica and the metal deactivator benzotriazole. The particle size of the benzotriazole is 0.6 - 1 micron, and the mass addition ratio of the nano-sized silica to benzotriazole is 2:1.

[0026] Adopting the above technical solution, during the preparation process of the resin matrix, nano-sized silica and benzotriazole are dispersed in the solvent ethanol. The fine particle molecules have formed an intermolecular force similar to hydrogen bonds in the environment of the organic solvent and adsorb each other. Such an intermolecular force compensates for the influence of benzotriazole in the form of a white crystalline powder with high purity on the transparency of the resin matrix, and effectively prevents the possibility of agglomeration of the inorganic filler after the solvent volatilizes. The fine particles, as auxiliary agents, are well dispersed into the three-dimensional network structure after the resin matrix is cross-linked, and can further enhance the hydrophobic effect on the surface of the thin film material.

[0027] Preferably, the antioxidant is at least one of phosphite antioxidant 168 and hindered phenol antioxidant YFK-1076.

[0028] Preferably, the graft monomer is a siloxane-based graft monomer, and the siloxane-based graft monomer includes at least one of vinyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane.

[0029] Adopting the above technical solution, the graft monomer with a Si-O-Si structure in the siloxane can not only provide good hydrophobicity but also improve the thermal stability and antioxidant capacity of the thin film material. Moreover, such a graft monomer has good anti-degradability and is not affected by irradiation during the simultaneous grafting and cross-linking process, and can ensure the expected grafting rate.

[0030] The present invention also provides a method for preparing the thin film material for semiconductors, comprising the following steps:

[0031] 1) Grafting: Dissolve the grafting monomer in DMSO to form a pre-grafting solution; mix and impregnate the pre-grafting solution with ethylene-vinyl acetate copolymer resin particles and a cross-linking agent; load into an electron beam irradiation device, add a nitrogen atmosphere for irradiation to obtain a grafted substrate;

[0032] 2) Mixing: Add silica and BTA to ethanol and ultrasonically disperse to obtain an auxiliary agent solution, and mix the coupling agent, flame retardant, antioxidant, and the auxiliary agent solution with the grafted substrate in step 1) to obtain a substrate mixture;

[0033] 3) Heating: Under heating conditions, simultaneously remove the organic solvent under negative pressure from the substrate mixture in step 2);

[0034] 4) Extrusion molding: On the basis of removing the organic solvent in step 3), remove the negative pressure and continue to raise the temperature for plasticization, and after the plasticization is completed, perform calendering to obtain the thin film material.

[0035] Adopting the above technical solution, the advantage of performing cross-linking and grafting simultaneously is that the obtained thin film material has good antibacterial properties; the sequence of irradiation first and then mixing can resist the decrease in polarity and the resulting decrease in bonding force caused by the hydrophobicity after the substrate is grafted, and promote the dispersion effect of the auxiliary agent in the substrate, further preventing agglomeration from affecting the uniformity and light transmittance of the thin film material.

[0036] Preferably, the irradiation dose of the electron beam in step 1) is 70-90 kGy.

[0037] Preferably, the monomer concentration of the pre-grafting solution in step 1) is 1.5-1.8%.

[0038] Adopting the above technical solution, appropriate irradiation dose and monomer concentration ensure that the effects of cross-linking and grafting are balanced with each other, the pores of the cross-linking are moderate, the surface of the thin film material is denser, the friction coefficient is reduced, and thus the processing performance of the material is improved.

[0039] The beneficial effects of the present invention:

[0040] 1) The components are compatible with each other, matching and compensating for each other's performance deficiencies, and the coordinated action improves the performance of the thin film material as a whole. Compared with a simple EVA thin film material, it has better heat dissipation and smaller thermal deformation.

[0041] 2) The obtained material has uniform properties, is hydrophobic on the surface and cross-linked on the inner layer. The obtained material has appropriate pores and high density, good flame retardancy, toughness, transparency, strong insulation performance, strong antioxidant performance, and is applicable to many scenarios.

[0042] 3) The processing method is simple, achieving grafting and crosslinking in one step. Appropriate processing conditions enable a balance between the grafting rate and the crosslinking degree, and the processing performance is strong. Detailed implementation manners

[0043] The present invention will be further described below through specific embodiments. In order to make the invention object, technical solution and beneficial technical effects of the present invention clearer, the present invention will be further described in detail below in conjunction with the embodiments. It should be understood that the embodiments described in this specification are only for explaining the present invention and not for limiting the present invention.

[0044] Unless otherwise stated, all the film adhesives and reagents used in the embodiments are commercially available or can be synthesized according to conventional methods, and can be directly used without further treatment, and the instruments used in the embodiments are all commercially available.

[0045] Experimental methods:

[0046] A. Refer to the standard GB / T 29848-2018, including: preparing several samples randomly selected from the same batch, depending on the actual situation, ensuring that the sampled samples are clean and pollution-free on the surface; generally, the sample size requirements for the experiment are usually 100 mm × 100 mm; placing the samples at room temperature and under the condition of relative humidity (50 ± 5)% for at least 24 hours; using a breakdown voltage tester that complies with the standard GB / T 1408.1, using a circular electrode with a diameter of 25 mm, and keeping the distance between the two electrodes constant; placing the above-mentioned several samples between the upper and lower electrodes to ensure good contact, and gradually increasing the voltage at a speed of (1 ± 0.2) kV / s until the specimen breaks down, recording the breakdown voltage value, and performing at least 5 tests on each sample and taking the average value as the final result.

[0047] B. Refer to the standard GB / T 1040.3-2006 to test the tensile toughness of the thin film material, and the steps can be found and will not be elaborated.

[0048] C. To test the water absorption of the material, the following steps are included: using a contact angle measuring instrument, an OCA20 type contact angle analyzer; taking several thin film material samples from the same batch, cleaning them thoroughly to ensure that there are no impurities on the surface; placing the samples on the platform of the contact angle measuring instrument, dropping 2 μL of pure water, and measuring the contact angle after 10 seconds; recording the contact angle value, and taking the average value after repeated measurement 3 times.

[0049] Example 1:

[0050] Preparation: 80 parts of ethylene-vinyl acetate copolymer, 5 parts of benzoyl peroxide, 0.2 part of TTS, 0.1 part of diisopropylaluminum distearate, 1.0 part of phosphite antioxidant 168, 1.0 part of hindered phenol antioxidant YFK-1076, 0.02 part of a mixture of triphenyl phosphate TPP and melamine cyanurate MCA, 0.02 part of 50-nanometer silica, 0.01 part of 0.6-μm metal deactivator benzotriazole;

[0051] Preparation method:

[0052] 1) Grafting: Dissolve vinyltrimethoxysilane in DMSO to form a pre-grafting solution with a concentration of 1.6%. Mix and impregnate the pre-grafting solution with ethylene-vinyl acetate copolymer resin particles and a crosslinking agent. Load it into an electron beam irradiation device, add a nitrogen atmosphere for irradiation, and the irradiation dose is 80 kGy to obtain a grafted substrate;

[0053] 2) Mixing: Add silica and BTA to ethanol and disperse them ultrasonically to obtain an auxiliary agent solution. Mix the coupling agent, flame retardant, antioxidant, and the auxiliary agent solution with the grafted substrate in step 1) to obtain a substrate mixture;

[0054] 3) Heating: Under heating conditions, simultaneously remove the organic solvent under negative pressure from the substrate mixture in step 2);

[0055] 4) Extrusion molding: On the basis of removing the organic solvent in step 3), remove the negative pressure and continue to heat and plasticize. After plasticization is completed, calender to obtain a film material.

[0056] Example 2:

[0057]

[0058] Preparation method:

[0059] 1) Grafting: Dissolve γ-methacryloxypropyltrimethoxysilane in DMSO to form a pre-grafting solution with a concentration of 1.8%. Mix and impregnate the pre-grafting solution with ethylene-vinyl acetate copolymer resin particles and a crosslinking agent. Load it into an electron beam irradiation device, add a nitrogen atmosphere for irradiation, and the irradiation dose is 90 kGy to obtain a grafted substrate;

[0060] 2) Mixing: Add silica and BTA to ethanol and disperse them ultrasonically to obtain an auxiliary agent solution. Mix the coupling agent, flame retardant, antioxidant, and the auxiliary agent solution with the grafted substrate in step 1) to obtain a substrate mixture;

[0061] 3) Heating: Under heating conditions, simultaneously remove the organic solvent under negative pressure from the substrate mixture in step 2);

[0062] 4) Extrusion molding: On the basis of removing the organic solvent in step 3), remove the negative pressure and continue to heat for plasticization. After the plasticization is completed, calendering is carried out to obtain a film material.

[0063] Example 3:

[0064]

[0065] 1) Grafting: Dissolve γ-methacryloxypropyltrimethoxysilane in DMSO to form a pre-grafting solution with a concentration of 1.5%. Mix the pre-grafting solution with ethylene-vinyl acetate copolymer resin particles and a cross-linking agent for impregnation. Load it into an electron beam irradiation device, add a nitrogen atmosphere for irradiation, and the irradiation dose is 70 kGy to obtain a grafted substrate;

[0066] 2) Mixing: Add silica and BTA to ethanol and disperse them by ultrasonic to obtain an auxiliary agent solution. Mix the coupling agent, flame retardant, antioxidant, and the auxiliary agent solution with the grafted substrate in step 1) to obtain a substrate mixture;

[0067] 3) Heating: Under heating conditions, remove the organic solvent under negative pressure for the substrate mixture in step 2);

[0068] 4) Extrusion molding: On the basis of removing the organic solvent in step 3), remove the negative pressure and continue to heat for plasticization. After the plasticization is completed, calendering is carried out to obtain a film material.

[0069] Example 4: Replace the coupling agent with 0.05 parts of TTS, and the rest is the same as in Example 1.

[0070] Example 5: Replace the coupling agent with 0.05 parts of aluminum isostearoyl lactate, and the rest is the same as in Example 2.

[0071] Comparative Example 1:

[0072] A semiconductor ETFE film includes ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, and composite reinforcing powder. Through the manufacturing method, it includes the following steps:

[0073] (1) Add aluminum silicate to anhydrous ethanol and stir at room temperature for 20 - 30 minutes, then add a silane coupling agent and mix, stir at room temperature for 12 - 24 hours, filter, wash the filter cake with an organic solvent 2 - 3 times, dry the filter cake at 70 - 80 °C for 2 - 4 hours to obtain modified aluminum silicate. Mix the modified aluminum silicate with molybdenum disulfide and disperse it with a high-speed mixer for 0.5 - 1 hour, and dry it in an oven at 90 - 100 °C for 0.5 - 1 hour to obtain a composite reinforcing powder;

[0074] (2) Mix the ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, and composite reinforcing powder, melt granulate through a twin-screw extruder, and then cool and form through a cooling roll to obtain an ETFE film.

[0075] The thin film materials of Examples 1-5 were compared with that of Comparative Example 1 in terms of insulation performance, mechanical properties, and moisture absorption resistance effect.

[0076] The results are shown in the following table:

[0077]

[0078] It can be seen from the above results that the coupling agent affects the interfacial bonding force. The compound coupling agent has a better effect on the mechanical strength of the thin film material. However, a single coupling agent still has obvious advantages compared with other materials; any combination of the crosslinking agent and graft monomer of the present invention basically has little influence on the material properties. That is to say, the component combination of the present invention, whether in terms of type or ratio, is a very reasonable choice. With the support of the preparation method of the present invention, the texture of the material can be accurately controlled, and it can adapt to various production conditions. Moreover, such a combination can ensure that when grafting and crosslinking are carried out simultaneously, the grafting rate and crosslinking pores can be well balanced without negative effects on each other. The result is reflected in the performance values presented by the material finally; the above several experimental effects prove that the thin film material of the present invention has good compactness, specifically manifested as good mechanical strength, excellent hydrophobic effect, and good resistance to the inherent hygroscopicity. More importantly, it still has good electrical insulation even when the thin film is very thin. As a semiconductor insulating material and packaging material, it has more advantages than other types of materials.

[0079] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. A thin film material for semiconductors, comprising a resin base material and a graft monomer, characterized in that, By weight parts, the resin base material comprises the following components:

2. The thin film material for semiconductor according to claim 1, wherein The crosslinking agent comprises at least one of benzoyl peroxide and TAIC.

3. A thin film material for semiconductors according to claim 1, characterized in that, The flame retardant is a mixture of organic nitrogen-based flame retardants and phosphorus-based flame retardants.

4. A thin film material for semiconductors according to claim 1, wherein, The coupling agent comprises at least one of TTS and diisopropyl stearoyl aluminate.

5. A thin film material for semiconductors according to claim 1, characterized in that, The antioxidant is at least one of phosphite antioxidant 168 and hindered phenol antioxidant YFK-1076.

6. A thin film material for semiconductors according to claim 1, characterized in that, The auxiliary agent is silica, benzotriazole BTA and its derivatives.

7. A thin film material for semiconductors according to claim 1, characterized in that, The graft monomer is a siloxane-based graft monomer, and the siloxane-based graft monomer comprises at least one of vinyltrimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane.

8. A method for preparing a thin film material for semiconductors as described in any one of claims 1-7, characterized in that, It comprises the following steps: 1) Grafting: Dissolve the graft monomer in DMSO to form a pre-grafting solution; mix and impregnate the pre-grafting solution with ethylene-vinyl acetate copolymer resin particles and a crosslinking agent; load into an electron beam irradiation device, add a nitrogen atmosphere for irradiation to obtain a grafted substrate. 2) Mixing: Ultrasonically disperse silica and BTA in ethanol to obtain an auxiliary agent solution, and mix the coupling agent, flame retardant, antioxidant, and the auxiliary agent solution with the grafted substrate in step 1) to obtain a substrate mixture. 3) Heating: Under heating conditions, simultaneously remove the organic solvent under negative pressure from the substrate mixture in step 2). 4) Extrusion molding: On the basis of removing the organic solvent in step 3), remove the negative pressure and continue to heat and plasticize. After plasticization is completed, calendering is carried out to obtain a film material.

9. The preparation method according to claim 8, characterized in that, In step 1), the irradiation dose of the electron beam is 70-90 kGy.

10. The preparation method according to claim 9, wherein, In step 1), the monomer concentration of the pre-grafting solution is 1.5-1.8%.

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