Solid wax for temporary bonding and preparation method and application thereof

Abstract

The invention provides solid wax for temporary bonding and a preparation method and application of the solid wax for temporary bonding, and the solid wax for temporary bonding is prepared from the following raw materials in parts by weight: 5-15 parts of thermoplastic resin; 30 to 35 parts of rosin derivative resin; 50 to 60 parts of a lubricant; and 2-5 parts of a plasticizer. The solid wax provided by the invention can provide strong supporting force for a wafer, and has relatively good protection capability for the wafer; the solid wax has a high softening point, can tolerate high temperature, can provide excellent bonding strength, and ensures that a wafer does not run and slip during grinding and polishing; the solid wax has an excellent self-leveling effect at a certain temperature, the prepared coating film has good TTV, the solid wax is easy to separate from a substrate after thinning cutting and heating, the process steps are simplified, and the residual gum is easy to clean by acetone or isopropanol.

Description

Technical Field

[0001] The invention belongs to the technical field of wafer production and processing, and relates to a solid wax for temporary bonding and a preparation method and application thereof. Background Art

[0002] In recent years, the performance of electronic components has been greatly improved due to technological innovation and the lightness, thinness and miniaturization of various devices. What makes this possible is the development of new packaging technology, which uses wafer thinning processing technology. In the wafer thinning process, the back of the wafer is ground and thinned. At this time, the front of the wafer needs to be temporarily fixed to the supporting substrate, and the temporary fixing adhesive used is particularly important.

[0003] WO2012176737A1 discloses a temporary fixing composition, which can fix a chip or metal with high adhesion, and can simply and cleanly peel off the chip or metal without damaging it. The temporary fixing composition contains 16 to 35 C α-olefin polymer resin, hydrogenated tackifier and hydrocarbon. Although the composition can solve the problem of wafer distortion caused by the curing shrinkage of other adhesives, and has a certain bonding strength; however, the softening point of the composition is low, so that the temperature tolerance of the wafer is low to ensure that the chip does not run and slide during grinding and polishing.

[0004] Therefore, in the art, it is desired to develop a solid wax for temporary bonding in the wafer thinning process, which has a high softening point, can withstand high temperatures, and can provide excellent bonding strength to ensure that the wafer does not run or slip during grinding and polishing. Summary of the invention

[0005] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a solid wax for temporary bonding and a preparation method and application thereof. The solid wax for temporary bonding provided by the present invention is an adhesive material that is solid at room temperature. The optical glass and the wafer can be quickly bonded at a certain temperature and pressure through the solid wax. After the subsequent processing is completed, the working material can be slid by heating the solid wax and applying a certain force, and the working material can be easily peeled off from the support. At the same time, the remaining solid wax can be removed by an organic solvent, which greatly simplifies the processing process.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a solid wax for temporary bonding, wherein the raw materials for preparing the solid wax for temporary bonding include the following components in parts by weight:

[0008]

[0009] The raw materials for preparing the solid wax for temporary bonding provided by the present invention include thermoplastic resin, rosin derivative resin with high softening point, high viscosity and oxidation resistance, lubricant and plasticizer. Through the screening and coordinated compounding of specific components, the solid wax can provide strong support for the wafer and has good protection ability for the wafer; the solid wax has a high softening point, high temperature tolerance, and can provide excellent bonding strength to ensure that the wafer does not run or slip during grinding and polishing; the solid wax has excellent self-leveling effect at a certain temperature, and the prepared coating has good TTV (that is, the total thickness of the coating changes little); after the thinning and cutting is completed, the solid wax is easily separated from the substrate after heating, the process steps are simplified, and the residual glue is easy to clean with acetone or isopropyl alcohol (IPA).

[0010] In the present invention, the addition of plasticizer can effectively improve the problem that the thermoplastic resin has strong supporting force but is easy to crack; the thermoplastic resin can provide sufficient supporting force for the material, and is combined with rosin derivative resin to prepare a solid wax with high hardness and strong adhesion; by introducing a lubricant, the prepared solid wax material can be demolded from the mold more easily, simplifying the difficulty of industrial operation.

[0011] The temporary bonding solid wax provided by the present invention can temporarily fix the wafer on the support plate before thinning, cutting, grinding and other processes, so as to support the wafer to complete the subsequent processing. The wafer can be simply slid off the support plate by heating, and the solid wax residue can be easily cleaned by using polar organic solvents such as acetone or IPA.

[0012] In the present invention, the raw materials for preparing the solid wax for temporary bonding are measured in parts by weight, and the amount of thermoplastic resin used can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 14 parts, 15 parts, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0013] In the present invention, the amount of the rosin derivative resin used in the preparation of the solid wax for temporary bonding can be 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, etc., based on parts by weight, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0014] In the present invention, the raw materials for preparing the solid wax for temporary bonding are measured in parts by weight, and the amount of lubricant used can be 50 parts, 51 parts, 52 parts, 53 parts, 54 parts, 55 parts, 56 parts, 57 parts, 58 parts, 59 parts, 60 parts, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0015] In the present invention, the amount of plasticizer used in the preparation of the solid wax for temporary bonding can be 2 parts, 3 parts, 4 parts, 5 parts, etc., based on weight parts, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] Preferably, the thermoplastic resin includes any one of terpene resin, terpene-phenolic resin, terpene-phenolic resin, hydrogenated petroleum resin, styrene-acrylic resin or acrylate resin, or a combination of at least two thereof.

[0017] Preferably, the hydrogenated petroleum resin includes C5 hydrogenated petroleum resin and / or C9 hydrogenated petroleum resin.

[0018] Preferably, the weight average molecular weight of the thermoplastic resin is 700-60000, for example 700, 800, 900, 1000, 3000, 5000, 8000, 10000, 15000, 20000, 25000, 30000, 35000, 40000, 45000, 50000, 55000, 60000, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] Preferably, the softening point of the thermoplastic resin is 90-150°C, for example 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] Preferably, the rosin derivative resin includes any one of water-white hydrogenated rosin resin, acrylic rosin resin, maleic rosin resin, rosin glycerol ester or rosin pentaerythritol ester, or a combination of at least two thereof.

[0021] Preferably, the weight average molecular weight of the rosin derivative resin is 300-6000, for example, 300, 500, 800, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] Preferably, the softening point of the rosin derivative resin is 80-150°C, for example 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] Preferably, the lubricant includes any one of stearic acid, stearic acid monoglyceride, tristearin, pentaerythritol stearate, ethylene bisstearamide (EBS wax), ethylene bisoleamide (EBO wax), polyethylene wax or beeswax, or a combination of at least two thereof.

[0024] Preferably, the stearic acid may be of grades SA1801, SA1810 or SA1840.

[0025] Preferably, the plasticizer includes any one of a phthalate plasticizer or a phosphate plasticizer, or a combination of at least two of them.

[0026] Preferably, the phthalate plasticizer includes any one of dimethyl phthalate (DMP), dibutyl phthalate (DBP), dioctyl phthalate (DOP) or a combination of at least two thereof;

[0027] Preferably, the phosphate plasticizer includes any one of tricresyl phosphate (TCP), triphenyl phosphate (TPP) or aromatic condensed phosphate (PX-200) or a combination of at least two thereof.

[0028] In a second aspect, the present invention provides a method for preparing the solid wax for temporary bonding as described in the first aspect, the preparation method comprising the following steps:

[0029] (1) Add lubricant and plasticizer into a stirrer, increase the temperature, and start stirring after the solid melts;

[0030] (2) slowly adding a thermoplastic resin into the stirrer of step (1), raising the temperature, adding a rosin derivative resin after the thermoplastic resin is melted, stirring evenly, filtering, discharging the material into a mold for injection molding, and obtaining the solid wax for temporary bonding.

[0031] Preferably, the agitator in step (1) comprises a stirring kettle.

[0032] Preferably, the heating in step (1) includes heating using a mold temperature controller.

[0033] Preferably, the temperature in step (1) is increased to 80-110°C, for example 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] Preferably, the stirring rate in step (1) is controlled at 50-100 rpm, for example, 50 rpm, 60 rpm, 70 rpm, 80 rpm, 90 rpm, 100 rpm, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0035] Preferably, the stirring time in step (1) is 10 to 30 min, for example, 10 min, 15 min, 20 min, 25 min, 30 min, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0036] Preferably, the temperature in step (2) is increased to 100-130°C, for example, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] Preferably, the stirring rate in step (2) is controlled at 70-120 rpm, for example 70 rpm, 80 rpm, 90 rpm, 100 rpm, 110 rpm, 120 rpm, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0038] Preferably, the stirring time in step (2) is 30 to 60 min, for example, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] Preferably, the filtration in step (2) is performed using a filter element of 0.2-1.0 μm (e.g., 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, etc.).

[0040] Preferably, the shape of the mold in step (2) includes sheet, cylinder or cuboid, which can be specifically set according to the use environment.

[0041] The preparation method of the solid wax for temporary bonding provided by the invention is simple.

[0042] In a third aspect, the present invention provides a use of the solid wax for temporary bonding as described in the first aspect in a wafer thinning process.

[0043] Preferably, the method of application comprises the following steps:

[0044] (a) placing a wafer and a device on a heating plate, heating them, coating the wafer with the temporary bonding solid wax, placing the device on the wafer, pressing and laminating the device, and cooling the device to room temperature to obtain a temporarily bonded wafer;

[0045] (b) The temporarily bonded wafer obtained in step (a) is subjected to grinding, polishing, photolithography, baking, chemical vapor deposition and other process technologies in sequence. After completion, the wafer is unloaded, and the surface of the wafer is cleaned with a cleaning agent, and finally rinsed with clean water and dried to complete the construction of the solid wax for temporary bonding.

[0046] Preferably, the size of the wafer in step (a) is 4 inches or 6 inches.

[0047] Preferably, the heating temperature in step (a) is controlled at 90-110°C, for example 90°C, 95°C, 100°C, 105°C, 110°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] Preferably, the cooling method in step (a) includes nitrogen cooling.

[0049] Preferably, the wafer unloading in step (b) is carried out at 90-120°C (for example, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, etc., but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable).

[0050] Preferably, the cleaning agent in step (b) comprises acetone and / or isopropyl alcohol.

[0051] Preferably, the cleaning method in step (b) includes soaking and / or spraying.

[0052] Compared with the prior art, the present invention has at least the following beneficial effects:

[0053] (1) The solid wax for temporary bonding provided by the present invention can provide strong support for the wafer and has good protection for the wafer;

[0054] (2) The solid wax for temporary bonding provided by the present invention has a high softening point, a high temperature tolerance, and can provide excellent bonding strength to ensure that the wafer does not run or slip during grinding and polishing;

[0055] (3) The solid wax for temporary bonding provided by the present invention has excellent self-leveling effect at a certain temperature and a good TTV of the prepared coating film (i.e., the total thickness of the coating film changes little). After the thinning and cutting is completed, the solid wax is easily separated from the substrate after heating, which simplifies the process steps. The solid wax residue can be easily cleaned with acetone or isopropyl alcohol. DETAILED DESCRIPTION

[0056] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0057] Unless otherwise specified, some raw material information involved in the following specific embodiments of the present invention is shown in Table 1 below. Other raw materials not shown are conventional materials in the art and can be purchased from commercial products.

[0058] Table 1

[0059]

[0060]

[0061] Examples 1 to 7 and Comparative Examples 1 to 4

[0062] Examples 1 to 7 and Comparative Examples 1 to 4 respectively provide a solid wax for temporary bonding, and the raw materials and amounts thereof are shown in Table 2. In Table 2, the unit of the amount of each component is "kg".

[0063] Table 2

[0064]

[0065] The preparation method of the solid wax for temporary bonding provided in Examples 1 to 7 and Comparative Examples 1 to 4 comprises the following steps:

[0066] Add lubricant and plasticizer to the stirring kettle, raise the temperature to 90°C (observe the melting of the material in the kettle during this period; if the melting rate of the material is slow, the temperature can be appropriately increased by 5-10°C), start stirring after the solid melts, and stir at a speed of 60rpm for 20min; then slowly add thermoplastic resin, raise the temperature to 110°C, add rosin derivative resin after the thermoplastic resin melts, adjust the speed to 80rpm, stir for 1h, and stop stirring when the material in the kettle becomes clear and transparent, filter, and discharge the material into a mold for injection molding to obtain the solid wax for temporary bonding.

[0067] Performance Testing

[0068] The performance test of the temporary bonding solid wax provided in the above embodiments and comparative examples is carried out, and the test method is as follows:

[0069] (1) Shore hardness measurement: The hardness of the wax body is generally measured using a Shore hardness tester. The Shore hardness is divided into two standards, Shore A and Shore D. The present invention adopts the Shore A standard. The larger the value measured by the durometer, the higher the hardness of the wax body.

[0070] (2) Melt viscosity: Anton Paar rheometer was used to measure the rheological viscosity of solid wax.

[0071] (3) Bonding strength: The equipment used for the bonding strength test is a universal material testing machine. During the test, apply the solid wax sample to the bonding area of ​​the heated test piece (the size is 15mm×25mm), and then bond the bonding areas of the two test pieces together. After the wax layer solidifies, cut off the overflowed wax layer, and then put the test piece into the fixture of the testing machine for tensile testing. When the test piece is broken by the testing machine, record the maximum tensile force at the time of fracture (in N). The maximum tensile force divided by the area of ​​the bonding area of ​​the test piece is the bonding strength of the sample, in N / mm 2 .

[0072] (4) Softening point: The softening point of solid wax is determined using the ring and ball method. The present invention specifically uses a ring and ball softening point tester to test the softening point. The test process is roughly as follows: heat and melt the solid wax sample to be tested, and then pour the melted sample into a small copper ring. After the sample is completely solidified, cut the sample into a wax block with the same thickness as the small copper ring. Then put the small copper ring with the wax block into the bracket hole of the tester, put in the large copper ring, and then put the steel ball into the hole of the large copper ring. Start the tester and start heating. When the steel ball is heated to the point where it escapes from the wax block and falls onto the receiving platform below, the corresponding temperature point at this time is the softening point of the sample, and the unit of the softening point is ℃.

[0073] (5) Film surface observation and cleaning test: Taking a 6-inch silicon wafer as an example, apply solid wax on the wafer heated at 100°C. After cooling, observe the film surface with the naked eye and a microscope. Observe whether the film surface of the temporarily bonded wafer has cracks. If no cracks are found, it means that the film surface is normal. If the film surface is uniform and smooth, it means that it is smooth. After observation, use a certain amount of acetone to soak the film surface for 1 minute, start spin coating (1000rpm), and use a dropper bottle to add acetone while spin coating for 2 minutes. Dry in an oven and observe whether there is any wax residue on the film surface under a microscope.

[0074] (6) Film thickness / TTV: measured using Corning Flatmaster 200 flatness tester.

[0075] The performance test results are shown in Tables 3 and 4.

[0076] Table 3

[0077]

[0078] Table 4

[0079]

[0080]

[0081] It can be seen from Table 3 and Table 4 that the bonding strength of the solid wax for temporary bonding provided in Examples 1-7 of the present invention is all within 0.6 N / mm2 The above films have good TTV (less than 0.6 μm), high softening point, and are easy to clean.

[0082] The bonding strength of the temporary bonding solid wax provided by Comparative Examples 1 and 2 prepared according to the disclosed patents is less than 0.3 N / mm 2 This is not conducive to the subsequent grinding and polishing process. Due to insufficient coating adhesion, the sapphire substrate wafer may slip during the grinding and polishing process, affecting the product yield.

[0083] Compared with the embodiment, the solid wax for temporary bonding provided in Comparative Examples 1-2 has a poor TTV of the film layer due to severe cracking of the film layer, and is not cleaned thoroughly with acetone, which affects the product use experience.

[0084] Compared with Example 5, the temporary bonding solid wax film provided in Comparative Examples 3-4 has a lower hardness and cannot provide sufficient support for the wafer, resulting in a risk of wafer breakage during the grinding and thinning process.

[0085] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the solid wax for temporary bonding and its preparation method and application, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A solid wax for temporary bonding, characterized in that: The raw materials for preparing the temporary bonding solid wax include the following components in parts by weight:

2. The solid wax for temporary bonding according to claim 1, characterized in that: The thermoplastic resin includes any one of terpene resin, terpene-phenolic resin, terpene-phenolic resin, hydrogenated petroleum resin, styrene-acrylic resin or acrylate resin, or a combination of at least two thereof; Preferably, the hydrogenated petroleum resin comprises C5 hydrogenated petroleum resin and / or C9 hydrogenated petroleum resin; Preferably, the weight average molecular weight of the thermoplastic resin is 700-60000; Preferably, the softening point of the thermoplastic resin is 90-150°C.

3. The solid wax for temporary bonding according to claim 1 or 2, characterized in that: The rosin derivative resin includes any one of water-white hydrogenated rosin resin, acrylic rosin resin, maleic rosin resin, rosin glycerol ester or rosin pentaerythritol ester, or a combination of at least two thereof; Preferably, the weight average molecular weight of the rosin derivative resin is 300-6000; Preferably, the rosin derivative resin has a softening point of 80-150°C.

4. The solid wax for temporary bonding according to any one of claims 1 to 3, characterized in that The lubricant includes any one of stearic acid, stearic acid monoglyceride, tristearic acid glyceride, pentaerythritol stearate, ethylene bisstearic acid amide, ethylene bisoleic acid amide, polyethylene wax or beeswax, or a combination of at least two thereof.

5. The solid wax for temporary bonding according to any one of claims 1 to 4, characterized in that: The plasticizer includes any one of phthalate plasticizers or phosphate plasticizers or a combination of at least two thereof; Preferably, the phthalate plasticizer includes any one of dimethyl phthalate, dibutyl phthalate, and dioctyl phthalate, or a combination of at least two thereof; Preferably, the phosphate plasticizer includes any one of tricresyl phosphate, triphenyl phosphate or aromatic condensed phosphate or a combination of at least two thereof.

6. A method for preparing a solid wax for temporary bonding as claimed in any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: (1) Add lubricant and plasticizer into a stirrer, increase the temperature, and start stirring after the solid melts; (2) adding a thermoplastic resin to the stirrer of step (1), raising the temperature, adding a rosin derivative resin after the thermoplastic resin is melted, stirring, filtering, and discharging the material into a mold for injection molding to obtain the solid wax for temporary bonding.

7. The preparation method according to claim 6, characterized in that: The agitator in step (1) comprises a stirring kettle; Preferably, the heating in step (1) includes heating using a mold temperature controller; Preferably, the heating in step (1) is to 80-110° C.; Preferably, the stirring rate in step (1) is controlled at 50-100 rpm; Preferably, the stirring time in step (1) is 10 to 30 minutes.

8. The preparation method according to claim 6 or 7, characterized in that: The heating in step (2) is to be raised to 100-130° C.; Preferably, the stirring rate in step (2) is controlled at 70-120 rpm; Preferably, the stirring time in step (2) is 30 to 60 minutes; Preferably, the filtration in step (2) is performed using a 0.2-1.0 μm filter element; Preferably, the shape of the mold in step (2) includes sheet, cylinder or cuboid.

9. Use of the solid wax for temporary bonding as claimed in any one of claims 1 to 5 in a wafer thinning process.

10. The use according to claim 9, characterized in that: The method of application comprises the following steps: (a) placing a wafer and a device on a heating plate, heating them, coating the wafer with the temporary bonding solid wax, placing the device on the wafer, pressing and laminating the device, and cooling the device to room temperature to obtain a temporarily bonded wafer; (b) subjecting the temporarily bonded wafer obtained in step (a) to grinding, polishing, photolithography, baking, and chemical vapor deposition processes in sequence, unloading the wafer after completion, and cleaning the surface of the wafer with a cleaning agent, and finally rinsing and drying the wafer with clean water to complete the construction of the solid wax for temporary bonding; Preferably, the size of the wafer in step (a) is 4 inches or 6 inches; Preferably, the heating temperature in step (a) is controlled at 90-110° C.; Preferably, the cooling method in step (a) comprises nitrogen cooling; Preferably, the unloading of the wafer in step (b) is performed at 90-120° C.; Preferably, the cleaning agent in step (b) comprises acetone and / or isopropanol; Preferably, the cleaning method in step (b) includes soaking and / or spraying.

Images