Wafer dicing protective film and method of using the same

Abstract

The present application relates to C09J7, more particularly, the present application relates to a wafer cutting protection film and its using method, the wafer cutting protection film is composed of silicone oil release layer, polyvinyl chloride layer, polyester coating and adhesive layer;Silicone oil release layer, polyvinyl chloride layer, polyester coating and adhesive layer are coated and bonded from top to bottom.Add 2-hydroxyethyl acrylate, and control the weight percentage of 2-hydroxyethyl acrylate in ethyl ester to be 1.65-1.77%, so that the protection film when applied to wafer, not only has suitable adhesion, makes its adhesion in 100-150g / 25mm, can protect wafer from being damaged in cutting process, makes it easy to peel after processing, no glue, ghost appears, more importantly, in the cutting process, also not easy to produce glue silk, indirectly ensure the quality of wafer in cutting, in addition, also make the protection film have stable toughness and other mechanical properties.

Description

Technical Field

[0001] This invention relates to C09J7, and more specifically, to a wafer dicing protective film and its application method. Background Technology

[0002] A wafer is a silicon chip used in silicon semiconductor circuits and plays an indispensable role in semiconductors. Wafer fabrication requires dicing, and during dicing, the wafer surface needs to be encapsulated and protected to prevent damage during dicing and to avoid a decrease in wafer yield.

[0003] Patent CN113150730B provides a protective adhesive for wafer dicing. The adhesive, obtained by adding bisphenol A epoxy resin and silica with a particle size of 0.1-75 μm, is coated onto the wafer surface and cured at 130°C for 1 hour before dicing, which can improve the wafer yield. Patent CN112724888B provides an adhesive, a wafer dicing protective film, its preparation method, and its application. By controlling the ratio of fluorinated monomers, soft monomers, and hard monomers, the resulting protective film exhibits water resistance and high-temperature resistance.

[0004] It is evident that most existing technologies only consider the direct impact of the protective film on the wafer, without taking into account the problem of vapor and splashes generated during the cutting process seeping into the gaps in the protective film, causing adhesive threads to form during the cutting process. Summary of the Invention

[0005] To address the aforementioned problems, the first aspect of this invention provides a wafer dicing protective film, which comprises a silicone oil release layer, a polyvinyl chloride layer, a polyester coating, and an adhesive layer; the silicone oil release layer, polyvinyl chloride layer, polyester coating, and adhesive layer are coated and bonded from top to bottom.

[0006] Preferably, the total thickness of the wafer dicing protective film is 80±10μm.

[0007] As a preferred embodiment of the present invention, the longitudinal tensile rate and transverse tensile rate of the polyvinyl chloride layer are both >200%, and the longitudinal tensile strength and transverse tensile strength are both >0.4MPa.

[0008] Preferably, the polyvinyl chloride layer contains the plasticizer diisononyl phthalate (DINP).

[0009] As a preferred embodiment of the present invention, the thickness of the polyester coating is ≥2μm.

[0010] As a preferred embodiment of the present invention, the acid value of the polyester coating is 2-4 KOH mg / g.

[0011] Preferably, the acid value of the polyester coating is 2-3 KOH mg / g.

[0012] As a preferred technical solution of the present invention, the raw materials of the adhesive layer include adhesive, diluent and crosslinking agent; the weight ratio of adhesive, diluent and crosslinking agent is (77-81):20:(0.97-1.85).

[0013] Preferably, the adhesive layer is prepared by mixing the raw materials of the adhesive, adding a diluent (specifically ethyl acetate) for dilution, then adding a crosslinking agent (specifically toluene diisocyanate), and stirring to obtain the final product.

[0014] As a preferred embodiment of the present invention, the raw materials of the adhesive include methyl ester, ethyl ester, butyl ester, octyl ester, acrylic acid, and tackifier.

[0015] Preferably, the raw materials for the rubber compound also include azobisisobutyronitrile (AIBN).

[0016] Preferably, the raw materials of the adhesive include 2-5 parts by weight of methyl ester, 220-245 parts by weight of ethyl ester, 25-27 parts by weight of butyl ester, 38-45 parts by weight of octyl ester, 1-3 parts by weight of acrylic acid, 21-23 parts by weight of tackifier and 0.15-0.25 parts by weight of azobisisobutyronitrile.

[0017] A further preferred option is styrene as the thickener.

[0018] As a preferred embodiment of the present invention, the weight ratio of methyl ester to butyl ester is (2-5):(25-27); the weight ratio of butyl ester to octyl ester is (25-27):(38-45).

[0019] Preferably, the methyl ester is methyl methacrylate; the butyl ester is n-butyl acrylate; and the octyl ester is octyl acrylate.

[0020] Preferably, the weight percentage of ethyl ester in the raw materials of the rubber compound is 69-71.2%.

[0021] As a preferred embodiment of the present invention, the ethyl ester includes 2-hydroxyethyl acrylate, and the weight percentage of 2-hydroxyethyl acrylate in the ethyl ester is 1.65-1.77%.

[0022] To prevent vapors and splashes generated during the cutting process from seeping into the gaps in the protective film and causing adhesive residue, the applicant unexpectedly discovered in experiments that adding a certain proportion of 2-hydroxyethyl acrylate to the adhesive layer, with ethyl acrylate accounting for 69-71.2% of the raw materials of the adhesive, and 2-hydroxyethyl acrylate accounting for 1.65-1.77% of the ethyl acrylate, resulted in a protective film with suitable adhesion (100-150g / 25mm) when applied to the wafer. This not only protects the wafer from damage during cutting and makes it easy to peel off after processing without residue or ghosting, but more importantly, it also reduces the formation of adhesive residue during cutting, indirectly ensuring the quality of the wafer during cutting. In addition, it also gives the protective film stable mechanical properties such as toughness. The applicant speculates that, under the action of toluene diisocyanate, the -NCO group and 2-hydroxyethyl acrylate synergistically improve the gel system of the adhesive. At the same time, controlling the weight ratio of methyl ester to butyl ester to (2-5): (25-27) and the weight ratio of butyl ester to octyl ester to (25-27): (38-45) affects the crosslinking density of the formed network crosslinking structure, resulting in the improvement of chemical and physical properties.

[0023] As a preferred embodiment of the present invention, the ethyl ester further includes at least one of ethyl acetate, methoxyethyl methacrylate, and ethyl cyanoacrylate.

[0024] Preferably, ethyl ester also includes ethyl acetate.

[0025] The second aspect of the present invention provides a method for using a wafer dicing protective film, wherein the method comprises: attaching an adhesive layer to the back of a wafer and dicing it at 60-100°C.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] By adding 2-hydroxyethyl acrylate and controlling the weight percentage of 2-hydroxyethyl acrylate in ethyl acrylate to be 1.65-1.77%, the protective film, when applied to wafers, not only possesses suitable adhesion (100-150g / 25mm), effectively protecting the wafer from damage during dicing and ensuring easy peeling after processing without residue or ghosting, but more importantly, it also minimizes the formation of adhesive threads during dicing, indirectly guaranteeing the quality of the wafer. Furthermore, it imparts stable toughness and other properties to the protective film. The chemical properties are controlled by adjusting the weight ratio of methyl ester to butyl ester to (2-5):(25-27); the weight ratio of butyl ester to octyl ester to (25-27):(38-45), and the thickness of the polyester coating to ≥2μm. This ensures a good synergistic effect between the adhesive layer and the polyester coating, guaranteeing the chemical stability of each layer and preventing the migration of plasticizers from the PVC layer to the adhesive layer during cutting. It also improves the compatibility between the adhesive layer, polyester coating, and PVC layer with the silicone release layer, reducing the likelihood of air bubbles and other gaps that could affect wafer quality. The wafer dicing protective film obtained by this invention effectively protects the wafer during dicing, making it less prone to slip line defects and stacking fault defects on the wafer crystals, thus improving the product yield. Attached Figure Description

[0028] Figure 1 The image shows a wafer after the wafer dicing protective film obtained in Example 1 is applied to the wafer and then diced. Detailed Implementation

[0029] Example

[0030] All raw materials used in the preparation of the compositions in the examples were commercially available. Specifically, the silicone release layer was purchased from Elkem Silicones (Shanghai) Co., Ltd., model SILCOLEAS UV POLY112; the polyvinyl chloride layer was purchased from Dongguan Baixin Plastic Products Co., Ltd., model 8116, with longitudinal and transverse elongation rates both >200%, and longitudinal and transverse tensile strengths both >0.4 MPa; the polyvinyl chloride layer contained the plasticizer diisononyl phthalate (DINP); and the polyester coating was purchased from SK Chemicals Co., Ltd. (Korea), model ES-300, with an acid value of 2-3 KOH mg / g.

[0031] Example 1

[0032] This example provides a wafer dicing protective film, which consists of a silicone oil release layer, a polyvinyl chloride layer, a polyester coating, and an adhesive layer; the silicone oil release layer, polyvinyl chloride layer, polyester coating, and adhesive layer are coated and bonded from top to bottom.

[0033] The total thickness of the wafer dicing protective film is 76 μm. The thickness of the polyester coating is 2 μm.

[0034] The raw materials for the adhesive layer include adhesive, diluent and crosslinking agent; the weight ratio of adhesive, diluent and crosslinking agent is 78.5:20:1.5.

[0035] The adhesive layer is prepared by mixing the raw materials of the adhesive, adding a diluent (specifically ethyl acetate) for dilution, then adding a crosslinking agent (specifically toluene diisocyanate), and stirring to obtain the final product.

[0036] The raw materials of the adhesive include 4 parts by weight of methyl ester, 234 parts by weight of ethyl ester, 26 parts by weight of butyl ester, 42 parts by weight of octyl ester, 2 parts by weight of acrylic acid, 22 parts by weight of tackifier and 0.2 parts by weight of azobisisobutyronitrile.

[0037] The thickener is styrene.

[0038] The weight ratio of methyl ester to butyl ester is 4:26; the weight ratio of butyl ester to octyl ester is 26:42.

[0039] Methyl ester is methyl methacrylate; butyl ester is n-butyl acrylate; octyl ester is octyl acrylate.

[0040] Ethyl esters include 2-hydroxyethyl acrylate and ethyl acetate, with 2-hydroxyethyl acrylate comprising 1.71% by weight in the ethyl esters.

[0041] Example 2

[0042] This example provides a wafer dicing protective film, which differs from Example 1 in that the total thickness of the wafer dicing protective film is 81 μm.

[0043] The thickness of the polyester coating is 3μm.

[0044] The raw materials for the adhesive layer include adhesive, diluent and crosslinking agent; the weight ratio of adhesive, diluent and crosslinking agent is 79:20:1.

[0045] Example 3

[0046] This example provides a wafer dicing protective film. Unlike Example 1, the raw materials for the adhesive include 3 parts by weight of methyl ester, 220-245 parts by weight of ethyl ester, 25.5 parts by weight of butyl ester, 40 parts by weight of octyl ester, 1.5 parts by weight of acrylic acid, 21 parts by weight of tackifier, and 0.2 parts by weight of azobisisobutyronitrile. The weight ratio of methyl ester to butyl ester is 3:25.5; the weight ratio of butyl ester to octyl ester is 25.5:40; and the ethyl ester includes 2-hydroxyethyl acrylate, with 2-hydroxyethyl acrylate comprising 1.75% of the total ethyl ester composition.

[0047] Example 4

[0048] This example provides a wafer dicing protective film. Unlike Example 1, the adhesive material comprises 2 parts by weight of methyl acrylate, 240 parts by weight of ethyl acrylate, 25 parts by weight of butyl acrylate, 41 parts by weight of octyl acrylate, 1.3 parts by weight of acrylic acid, 21.7 parts by weight of tackifier, and 0.2 parts by weight of azobisisobutyronitrile. The weight ratio of methyl acrylate to butyl acrylate is 2:25; the weight ratio of butyl acrylate to octyl acrylate is 25:41; and the ethyl acrylate includes 2-hydroxyethyl acrylate, with 2-hydroxyethyl acrylate comprising 1.5% of the total ethyl acrylate.

[0049] Example 5

[0050] This example provides a wafer dicing protective film. Unlike Example 1, the adhesive layer consists of adhesive, diluent, and crosslinking agent; the weight ratio of adhesive, diluent, and crosslinking agent is 78:20:2.

[0051] Performance testing:

[0052] 1. Adhesion test: in accordance with GB / T2792 The adhesion and initial tack of the wafer dicing protective films obtained in Examples 1-5 were tested according to GB / T 4852 and the results are shown in Table 1:

[0053] Table 1

[0054]

[0055] 2. Mechanical property testing: The elongation at break of the wafer dicing protective film obtained in Examples 1-5 were tested according to ASTM-D-882. The wafer dicing protective film was left to stand at 25℃ and 40% humidity for 30 days, then placed at 100℃ for 7 hours, and then removed and tested again for its elongation at break. The results are shown in Table 2:

[0056] Table 2

[0057]

[0058] 3. Wafer dicing test: The wafer dicing protective film obtained in Examples 1-5 was applied to the back of a wafer (from Guangdong Shuocheng Technology Co., Ltd.), and dicing was performed at 85°C. The presence of adhesive threads during dicing, residual adhesive after dicing, and uneven or damaged wafer edges were observed. The results are shown in Table 3. Images of the wafer obtained after dicing in Example 1 are shown below. Figure 1 .

[0059] Table 3

[0060]

Claims

1. A wafer dicing protective film, characterized in that, The wafer dicing protective film consists of a silicone oil release layer, a polyvinyl chloride layer, a polyester coating, and an adhesive layer; the silicone oil release layer, polyvinyl chloride layer, polyester coating, and adhesive layer are coated and bonded from top to bottom; The adhesive layer is made of adhesive, diluent and crosslinking agent; the weight ratio of adhesive, diluent and crosslinking agent is (77-81):20:(0.97-1.85). The diluent is ethyl acetate, and the crosslinking agent is toluene diisocyanate; The raw materials for the rubber compound are 2-5 parts by weight of methyl ester, 220-245 parts by weight of ethyl ester, 25-27 parts by weight of butyl ester, 38-45 parts by weight of octyl ester, 1-3 parts by weight of acrylic acid, 21-23 parts by weight of tackifier and 0.15-0.25 parts by weight of azobisisobutyronitrile; The weight ratio of methyl ester to butyl ester is (2-5):(25-27); the weight ratio of butyl ester to octyl ester is (25-27):(38-45). The thickener is styrene; The methyl ester is methyl methacrylate; the butyl ester is n-butyl acrylate; the octyl ester is octyl acrylate; The ethyl ester is 2-hydroxyethyl acrylate and ethyl acetate, wherein the weight percentage of 2-hydroxyethyl acrylate in the ethyl ester is 1.65-1.77%. The thickness of the polyester coating is ≥2μm, and the acid value of the polyester coating is 2-4KOH mg / g; The adhesive layer is attached to the back of the wafer and cut at 60-100°C.

2. The wafer dicing protective film according to claim 1, characterized in that, The longitudinal and transverse tensile rates of the polyvinyl chloride layer are both greater than 200%, and the longitudinal and transverse tensile strengths are both greater than 0.4 MPa.

3. A method of using the wafer dicing protective film according to claim 1, characterized in that, The method of use is as follows: apply the adhesive layer to the back of the wafer and cut it at 60-100℃.

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