Solid wax for temporary bonding as well as preparation method and application of solid wax

Abstract

The invention belongs to the technical field of semiconductor polishing, and particularly discloses solid wax for temporary bonding and a preparation method and application thereof. The solid wax for temporary bonding is prepared from the following components in parts by weight: 40 to 60 parts of hydrogenated rosin, 20 to 40 parts of stearic acid, 15 to 20 parts of C5 petroleum resin and 0.1 to 1 part of fumed silica. The hydrogenated rosin, the stearic acid, the C5 petroleum resin and the fumed silica are combined to obtain the solid wax with good comprehensive performance, and the solid wax is high in bonding strength, low in melt viscosity and high in normal-temperature hardness, and can be well applied to the field of semiconductor polishing as a temporary adhesive, so that polished and ground wafers do not run and leak liquid. In addition, the solid wax is simple in raw material composition, few in added resin types and simple in manufacturing step, and the product cost can be effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor polishing, and in particular to a solid wax for temporary bonding and a preparation method and application thereof. Background Art

[0002] In the chemical mechanical polishing of semiconductors, a temporary adhesive is required to adhere the wafer to be polished and ground to the processing substrate (such as a ceramic disk). Common temporary bonding methods include liquid wax, adsorption pads, pyrolytic adhesives, solid wax, etc. Liquid wax can only be used in situations where the bonding strength requirement is not high due to its limited bonding strength; the adsorption pad is attached by physical means, and it is easy to have unstable bonding during the processing process, resulting in slippage; the pyrolytic adhesive needs to be heated with a hot air gun when removing the wafer, and the heating time is long, the operation is cumbersome, and the thickness of the pyrolytic adhesive is relatively thick, which will also affect the processing effect. Solid wax is suitable for various scenarios of bonding semiconductor wafers because of its good operability and good bonding performance.

[0003] The existing solid wax products on the market are mainly a mixture of rosin and other resins plus other additives, and have the following main defects: First, the product has a high melt viscosity, which will lead to poor fluidity, and may further cause the melted wax to flow unevenly on the polishing substrate. After the chip is attached, it may appear uneven, affecting the polishing effect; second, the bonding strength is insufficient, which makes it difficult to meet the semiconductor industry's demand for high-strength adhesives.

[0004] Chinese patent document CN102936485B discloses a solid wax with microcrystalline wax, synthetic wax, amide wax, rosin and modified rosin as main components. The viscosity and fluidity of the solid wax of this invention after melting are good, but the bonding strength needs to be further improved; Chinese patent document CN114634793A discloses a solid wax with polyethylene glycol, rosin, modified rosin, beeswax, microcrystalline wax and C5 petroleum resin as main components. The softening point and melting viscosity of the solid wax of this invention are moderate, but the hardness of the solid wax at room temperature is reduced due to the addition of beeswax, thereby affecting the bonding strength. Summary of the invention

[0005] To solve the above problems, the present invention provides a solid wax for temporary bonding and a preparation method and use thereof. The solid wax has high bonding strength and hardness, low melting viscosity, simple ingredients and low cost.

[0006] In order to achieve the above object, the specific technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a solid wax for temporary bonding, the components of which include, by weight: 40-60 parts of hydrogenated rosin, 20-40 parts of stearic acid, 15-20 parts of C5 petroleum resin, and 0.1-1 part of fumed silica.

[0008] The present invention mainly uses hydrogenated rosin with higher self-bonding strength to replace rosin, adds C5 petroleum resin to increase the bonding strength of the solid wax product, and then adds fumed silica to further improve the bonding strength. Hydrogenated rosin is a modified rosin after dehydrogenation treatment of ordinary rosin, and has stronger bonding performance than ordinary rosin. Since the mixture of hydrogenated rosin and stearic acid has good fluidity in a molten state, but the bonding strength is not high enough, on the existing basis, C5 petroleum resin with higher self-bonding strength is used to replace part of the hydrogenated rosin, and the bonding strength is greatly improved without affecting the overall melting viscosity of the solid wax. Stearic acid can well blend several resins that play a bonding role, and at the same time make the hardness of the finished product higher and the bonding strength better. Finally, adding a small amount of fumed silica on the basis of hydrogenated rosin, stearic acid and C5 petroleum resin can further improve the overall bonding effect. As a kind of silane coupling agent, fumed silica can undergo a coupling reaction between the adhesive and the bonded wafer to form a high-strength chemical bond, thereby greatly improving the bonding strength of the product.

[0009] Preferably, the fumed silica is oil-soluble fumed silica with a primary particle size of 7-40 nm and a specific surface area of ​​100-400 m 2 / g range, SiO 2 The content is not less than 99.8%.

[0010] Preferably, the acid value of the hydrogenated rosin is 150-180 mgKOH / g and has good heat resistance.

[0011] Preferably, the softening point of the C5 petroleum resin is between 95-105°C, the acid value is between 0-0.5 mg KOH / g, and the specific gravity is between 0.96-0.98 g / cm 3 .

[0012] Preferably, the softening point of the stearic acid is between 60-80° C. and the purity is >98%.

[0013] In a second aspect, the present invention provides a method for preparing the above-mentioned solid wax for temporary bonding, the method comprising the following steps:

[0014] (1) preparing hydrogenated rosin, stearic acid, C5 petroleum resin and fumed silica in proportion;

[0015] (2) Add hydrogenated rosin and C5 petroleum resin to a heating container, and set the heating temperature to 170-180° C. No stirring is required during this process, which saves effort and can also avoid the problem of raw materials sticking to the wall caused by stirring before the solid is completely melted, as well as the difficulty in cleaning the container and the loss of component content caused by it;

[0016] (3) After the above substances are heated until dissolved, add the prepared stearic acid and stir gently with a stirring rod;

[0017] (4) After the above substances are completely dissolved, add fumed silica, and then slowly stir with a stirring rod until completely mixed;

[0018] (5) During the stirring process, a stirring rod is needed to scrape off the material adhering to the wall of the heating container for further stirring to avoid affecting the final content of each substance in the finished product.

[0019] In the third aspect, the present invention provides the use of the above-mentioned solid wax for temporary bonding in the field of semiconductor polishing, which can be specifically used as a wafer bonding wax, and the wafer to be polished and ground is pasted on the processing substrate for temporary fixation, so that the wafer can be polished. After the polishing is completed and the solid wax is heated, the wafer can be removed, and it is not easy to have residues on the wafer. The solid wax of the present invention has the following advantages when used as a wafer bonding wax: First, it does not run away. The solid wax of the present invention has high bonding strength, can achieve a relatively firm temporary fixation, and is not easy to shift after polishing; and the solid wax will not react with the components of the polishing liquid, and there is no problem of wafer displacement caused by the failure of the solid wax due to the reaction. Second, it is liquid-proof. Since the solid wax will not react with the components of the polishing liquid, the problem of the polishing liquid seeping into the middle of the wafer and the substrate after the reaction and affecting the polishing effect will not occur; and the solid wax of the present invention has low melting viscosity and good fluidity, and the problem of uneven wafer bonding and pores due to poor wax melting fluidity and the phenomenon of polishing liquid infiltration caused by this problem will not occur.

[0020] The present invention has the following beneficial effects:

[0021] 1. The present invention combines hydrogenated rosin, stearic acid, C5 petroleum resin and fumed silica to obtain a solid wax with good comprehensive properties, such as high bonding strength, low melt viscosity and high hardness at room temperature.

[0022] 2. The raw material composition of the present invention is simple, the types of added resins are relatively small, the production steps are simple, and the product cost can be effectively reduced.

[0023] 3. The solid wax of the present invention can be well applied in the field of semiconductor polishing. As a temporary adhesive, it has strong bonding properties and can prevent the wafer from running or leaking after polishing and grinding, thus ensuring a good wafer polishing effect. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with specific examples. The performance parameter information of the raw materials used in the examples and comparative examples is as follows:

[0025] Hydrogenated rosin: acid value is 150-180mgKOH / g;

[0026] Stearic acid: melting point between 60-80°C, purity>98%;

[0027] C5 petroleum resin: softening point between 95-105℃, acid value between 0-0.5mg KOH / g, specific gravity between 0.96-0.98g / cm 3 ;

[0028] Fumed silica: oil-soluble gas silica, with a primary particle size of 7-40nm and a specific surface area of ​​100-400m 2 / g range, SiO 2 The content is not less than 99.8%.

[0029] Example 1

[0030] A solid wax for temporary bonding comprises the following components: 50 parts of hydrogenated rosin, 30 parts of stearic acid, and 20 parts of C5 petroleum resin. The solid wax is prepared according to the following method:

[0031] (1) Prepare hydrogenated rosin, stearic acid and C5 petroleum resin in proportion;

[0032] (2) Add hydrogenated rosin and C5 petroleum resin into a heating container and set the heating temperature to 170-180°C. No stirring is required during this process.

[0033] (3) After the above substances are heated until dissolved, add the prepared stearic acid and stir lightly with a stirring rod; (4) During the stirring process, the stirring rod needs to be used to scrape off the substances adhering to the wall of the heating container and further stir to avoid affecting the final content of each substance in the finished product.

[0034] Example 2

[0035] A solid wax for temporary bonding comprises the following components: 50 parts of hydrogenated rosin, 30 parts of stearic acid, 19.9 parts of C5 petroleum resin, and 0.1 parts of fumed silica. The solid wax is prepared according to the following method:

[0036] (1) preparing hydrogenated rosin, stearic acid, C5 petroleum resin and fumed silica in proportion;

[0037] (2) Add hydrogenated rosin and C5 petroleum resin into a heating container and set the heating temperature to 170-180°C. No stirring is required during this process.

[0038] (3) After the above substances are heated until dissolved, add the prepared stearic acid and stir gently with a stirring rod;

[0039] (4) After the above substances are completely dissolved, add fumed silica, and then slowly stir with a stirring rod until completely mixed;

[0040] (5) During the stirring process, a stirring rod is needed to scrape off the material adhering to the wall of the heating container for further stirring to avoid affecting the final content of each substance in the finished product.

[0041] Example 3

[0042] A solid wax for temporary bonding comprises the following components: 50 parts of hydrogenated rosin, 30 parts of stearic acid, 19.8 parts of C5 petroleum resin, and 0.2 parts of fumed silica. The preparation method of the solid wax is the same as that of Example 2.

[0043] Example 4

[0044] A solid wax for temporary bonding comprises the following components: 50 parts of hydrogenated rosin, 30 parts of stearic acid, 19.5 parts of C5 petroleum resin, and 0.5 parts of fumed silica. The preparation method of the solid wax is the same as that of Example 2.

[0045] Example 5

[0046] A solid wax for temporary bonding comprises the following components: 70 parts of hydrogenated rosin, 10 parts of stearic acid, 19.8 parts of C5 petroleum resin, and 0.2 parts of fumed silica. The preparation method of the solid wax is the same as that of Example 2.

[0047] Example 6

[0048] A solid wax for temporary bonding comprises the following components: 30 parts of hydrogenated rosin, 50 parts of stearic acid, 19.8 parts of C5 petroleum resin, and 0.2 parts of fumed silica. The preparation method of the solid wax is the same as that of Example 2.

[0049] Example 7

[0050] A solid wax for temporary bonding comprises the following components: 10 parts of hydrogenated rosin, 70 parts of stearic acid, 19.8 parts of C5 petroleum resin, and 0.2 parts of fumed silica. The preparation method of the solid wax is the same as that of Example 2.

[0051] Comparative Example 1

[0052] This comparative example is a preferred formula of the solid wax of Chinese patent document CN102936485B, which specifically includes the following components: 10 parts of hydrogenated rosin, 5 parts of microcrystalline wax, 10 parts of synthetic wax, 10 parts of amide wax, and 65 parts of rosin.

[0053] Comparative Example 2

[0054] This comparative example is a preferred formula of the solid wax of Chinese patent document CN114634793A, which specifically includes the following components: 50 parts of hydrogenated rosin, 5 parts of C5 petroleum resin, 5 parts of microcrystalline wax, 20 parts of rosin, 10 parts of polyethylene glycol, and 10 parts of beeswax.

[0055] The components of the above embodiments and comparative examples are summarized in Table 1 below:

[0056] Table 1: Component formula of each embodiment and comparative example

[0057]

[0058] The performance of the temporary fixing adhesives obtained in each embodiment and comparative example was evaluated, and the evaluation indexes and methods were as follows:

[0059] 1. Adhesion strength evaluation: Use a pair of stainless steel clips with a size of 100mm*25mm*1.5mm, heat to 120℃, then apply solid wax on the heated stainless steel clips to melt the solid wax on the clips, and tightly fit the ends of the pair of stainless steel clips together and cool to room temperature. The bonding area is 12.5mm*25mm. Then, according to the provisions of the national standard GB-T7124-2008, a tensile shear bonding strength test is performed, the stainless steel clips are pulled apart, and the fracture stress of the pulled apart clips is measured.

[0060] 2. Melt viscosity evaluation: After sample preparation, use a melt viscosity tester for measurement. Test instrument: Thermo HAAKEMARS 60; Test fixture: 35mm diameter parallel plate. According to the actual application, focus on comparing the viscosity at temperatures of 80℃, 100℃ and 120℃.

[0061] 3. Hardness evaluation: After sample preparation, use a Shore A hardness tester to measure. The test method is to measure 3 points and take the average value as the hardness value.

[0062] The evaluation results of each indicator are shown in Table 2 below:

[0063] Table 2: Evaluation results of various examples and comparative examples

[0064]

[0065] By comparing Examples 1, 2, 3, and 4, it can be seen that as the amount of fumed silica increases, the bonding strength first increases and then decreases. This is because the addition of an appropriate amount of fumed silica can significantly improve the overall bonding strength of the solid wax, while excessive addition will cause the hardness of the finished product to decrease, thereby affecting the bonding strength.

[0066] By comparing Examples 3, 5, 6, and 7, it can be seen that as the amount of stearic acid increases, the hardness of the solid wax changes very little, but the bonding strength gradually decreases with the increase of stearic acid. Therefore, an appropriate amount of stearic acid can improve the hardness while ensuring the bonding strength.

[0067] Among the 7 embodiments, the formulations of embodiments 2-4 are within the scope of the present invention, and the solid waxes prepared according to the three groups of formulations have higher bonding strength, lower melt viscosity and higher hardness, among which embodiments 2 and 3 have better performance.

[0068] Comparative Example 1 is a preferred formula of the solid wax of Chinese patent document CN102936485B, which is inferior to Examples 2 and 3 in terms of bonding strength, melt viscosity and hardness, and inferior to Example 4 in terms of melt viscosity and hardness.

[0069] Comparative Example 2 is a preferred formula of the solid wax of Chinese patent document CN114634793A, which is inferior to Examples 2 and 3 in terms of bonding strength, melt viscosity and hardness, and inferior to Example 4 in terms of melt viscosity and hardness.

[0070] This specific implementation is only an explanation of the present invention, not a limitation of the present invention. Any changes made by those skilled in the art after reading the specification of the present invention will be protected by the patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A solid wax for temporary bonding, characterized in that: The components thereof include, by weight: 40-60 parts of hydrogenated rosin, 20-40 parts of stearic acid, 15-20 parts of C5 petroleum resin, and 0.1-1 part of fumed silica.

2. The solid wax for temporary bonding according to claim 1, characterized in that: The fumed silica is oil-soluble fumed silica with a primary particle size of 7-40 nm and a specific surface area of ​​100-400 m 2 / g range, and the SiO2 content is not less than 99.8%.

3. The solid wax for temporary bonding according to claim 1, characterized in that: The acid value of the hydrogenated rosin is 150-180 mgKOH / g.

4. The solid wax for temporary bonding according to claim 1, characterized in that: The softening point of the C5 petroleum resin is between 95-105°C, the acid value is between 0-0.5 mg KOH / g, and the specific gravity is between 0.96-0.98 g / cm 3 .

5. The solid wax for temporary bonding according to claim 1, characterized in that: The softening point of the stearic acid is between 60-80° C. and the purity is >98%.

6. The method for preparing the solid wax for temporary bonding according to any one of claims 1 to 5, characterized in that: The following steps are included: (1) preparing hydrogenated rosin, stearic acid, C5 petroleum resin and fumed silica in proportion; (2) Add hydrogenated rosin and C5 petroleum resin into a heating container and set the heating temperature to 170-180°C. No stirring is required during this process. (3) After the above substances are heated until dissolved, add the prepared stearic acid and stir gently with a stirring rod; (4) After the above substances are completely dissolved, add fumed silica, and then slowly stir with a stirring rod until completely mixed; (5) During the stirring process, a stirring rod is needed to scrape off the material adhering to the wall of the heating container for further stirring to avoid affecting the final content of each substance in the finished product.

7. Use of the temporary bonding solid wax according to any one of claims 1 to 5 as wafer bonding wax in the field of semiconductor polishing.

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