Liquid wax with low thermal stress as well as preparation method and application of liquid wax

Abstract

The invention provides low-thermal-stress liquid wax as well as a preparation method and application thereof. The low-thermal-stress liquid wax comprises the following components in parts by weight: 10-60 parts of a polar solvent; 10 to 40 parts of a non-polar solvent; 1 to 5 parts of tackifying resin; 0.05 to 0.5 part of a covalent organic framework material; 0.1 to 1.5 parts of an inorganic nano material; 0.2 to 1 part of a coupling agent; and 20-30 parts of modified phenolic resin. The modified phenolic resin is xylene modified phenolic resin, due to the introduction of a hydrophobic xylene structure, the water resistance and alkali resistance of the xylene modified phenolic resin are improved, and the thermal stability is improved, so that the processing window of the low-thermal-stress liquid wax is further expanded. The low-thermal-stress liquid wax disclosed by the invention is low in wafer warpage value and low in thermal expansion coefficient, can effectively reduce wafer warpage, and has good application prospects and large-scale popularization potential in the field of temporary wafer bonding.

Description

Technical Field

[0001] The present invention relates to liquid wax technology, in particular to a low thermal stress liquid wax and a preparation method and application thereof. Background Art

[0002] Three-dimensional integration technology stacks multiple wafers through vertical interconnection, which can significantly reduce power consumption, improve electrical performance, reduce package size and increase integration density. However, this technology usually requires thinning the wafers, and the mechanical strength of the thinned wafers is significantly reduced, making them prone to problems such as warping and surface depressions. To ensure the process feasibility of thin wafers, temporary bonding technology is currently commonly used, that is, the device wafer is temporarily bonded to the carrier wafer through liquid wax, so that it can be subsequently processed like a standard thickness wafer. After the back-side processing is completed, the thinned wafer is separated from the carrier and adhered to the cutting frame to be divided into chips.

[0003] During the use of temporary bonding liquid wax, it needs to undergo various processing processes together with the device wafer, such as high temperature (250°C and above), chemical reagent (such as: polar solvent, strong acid) treatment, etc. At present, the mainstream liquid wax is mainly made of thermoplastic resin as raw material. Thermoplastic resin is prone to accumulate thermal stress when experiencing large temperature changes, causing device wafer warping. Excessive wafer warping will cause various defects and failures such as interface delamination and fracture, and will prevent subsequent processes from proceeding smoothly. The stress caused by warping is easy to concentrate in the interposer or solder joints, causing the solder balls to crack and fall off, and the interposer to delaminate. With the widespread application of large-size wafers in wafer-level packaging, the larger the wafer size, the stronger the thermal and mechanical stress it bears, the higher the local curvature, and the more serious the warping phenomenon. With the application of large-size wafers in wafer-level packaging, the problem of wafer warping has become a prominent problem restricting the development of wafer-level packaging technology.

[0004] In summary, in order to effectively solve the wafer warpage problem, it is urgent to develop a liquid wax with low thermal stress characteristics. Summary of the Invention

[0005] The purpose of the present invention is to propose a low thermal stress liquid wax to address the problem that traditional liquid wax easily causes device wafer warping. The low thermal stress liquid wax has a low wafer warping (WARP) value and a low thermal expansion coefficient, can effectively reduce wafer warping, and has good application prospects and large-scale promotion potential in the field of temporary wafer bonding.

[0006] It should be noted that, in the present invention, unless otherwise specified, the specific meaning of "including" in relation to composition limitations and descriptions includes both open-ended "including", "comprising", etc. and similar meanings, as well as closed-ended "composed of", "composed of", etc. and similar meanings.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a low thermal stress liquid wax, comprising the following components in the following weight proportions:

[0008]

[0009] Furthermore, the polar solvent is one or more of cyclopentanone, butanone, diethylene glycol butyl ether, dipropylene glycol methyl ether and diethylene glycol ethyl ether.

[0010] Furthermore, the polar solvent is preferably cyclopentanone.

[0011] Furthermore, the polar solvent is 20 to 60 parts.

[0012] Furthermore, the non-polar solvent is one or more of cyclopentane, pentane, isopentane and trimethylpentane.

[0013] Furthermore, the non-polar solvent is preferably cyclopentane.

[0014] Furthermore, the non-polar solvent is 10 to 30 parts.

[0015] Furthermore, the tackifying resin is one or more of polyvinyl butyral, polyvinyl formal and polyvinyl formal acetaldehyde.

[0016] Furthermore, the weight average molecular weight (Mw) of the tackifying resin is 15,000 to 50,000.

[0017] Furthermore, the tackifying resin is preferably polyvinyl butyral.

[0018] Furthermore, the tackifying resin is 2 to 5 parts.

[0019] Furthermore, the covalent organic framework material is one or more of COF-42, COF-5, COF-300 and PI-COF-1.

[0020] Furthermore, the covalent organic framework material is preferably COF-42.

[0021] Furthermore, the covalent organic framework material is 0.1 to 0.2 parts.

[0022] Furthermore, the inorganic nanomaterial is one or more of nano-silicon dioxide, nano-silicon carbide and nano-aluminum titanate.

[0023] Furthermore, the inorganic nanomaterial is preferably nano-silicon dioxide.

[0024] Furthermore, the inorganic nanomaterial is 0.5 to 1.5 parts.

[0025] Furthermore, the mass ratio of the covalent organic framework material to the inorganic nanomaterial is 1:1-10.

[0026] Furthermore, the coupling agent is one or more of γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

[0027] Furthermore, the coupling agent is preferably γ-aminopropyltriethoxysilane.

[0028] Furthermore, the coupling agent is 0.2 to 0.6 parts.

[0029] Furthermore, the xylene-modified phenolic resin is prepared by the following method:

[0030] Under the action of a catalyst, xylene formaldehyde resin, phenol, m-diphenol and formaldehyde are mixed and reacted at 60-120° C. for 5-180 minutes to complete the condensation reaction; a terminator is added, the temperature is raised to 100-200° C. and maintained for 30-180 minutes for distillation to distill out water and other volatile small molecules, thereby preparing the xylene-modified phenolic resin.

[0031] Furthermore, the catalyst is C1-C 15 One or more of alkylbenzenesulfonic acids.

[0032] Furthermore, the terminator is sodium hydroxide.

[0033] Furthermore, the weight average molecular weight (Mw) of the modified phenolic resin is 200-1000.

[0034] Furthermore, the modified phenolic resin is 20 to 25 parts.

[0035] Furthermore, the mass ratio of the xylene formaldehyde resin, phenol, m-diphenol and formaldehyde is 50-180:200-400:20-100:30-200.

[0036] Furthermore, the amount of the catalyst used is 0.001 to 0.005 times the total mass of the reactants.

[0037] Furthermore, the amount of the terminator is 0.01 to 0.03 times the total mass of the reactants.

[0038] Furthermore, the temperature of the condensation reaction is preferably 100° C.; and the time of the condensation reaction is preferably 30 minutes.

[0039] Furthermore, the temperature of the distillation is preferably 180° C.; and the time of the distillation is preferably 60 minutes.

[0040] Another object of the present invention is to disclose a method for preparing a low thermal stress liquid wax, comprising the following steps:

[0041] Step (1) stirring and mixing a polar solvent, a non-polar solvent and a coupling agent to obtain a solution;

[0042] Step (2) heating the solution obtained in step (1) to 30-50° C., adding a tackifying resin and a xylene-modified phenolic resin under stirring, stirring and mixing to obtain a mixed solution;

[0043] Step (3) adds inorganic nanomaterials and covalent organic framework materials to the mixed solution obtained in step (2) under stirring conditions, and stirs and mixes to obtain low thermal stress liquid wax.

[0044] Furthermore, the stirring speed in step (1) is 100 to 300 rpm.

[0045] Furthermore, the stirring and mixing time in step (1) is 1 to 10 minutes.

[0046] Furthermore, in step (2), the solution obtained in step (1) is heated to 30-40°C.

[0047] Furthermore, the stirring speed in step (2) is 100 to 300 rpm.

[0048] Furthermore, the stirring and mixing time in step (2) is 30 to 90 minutes.

[0049] Furthermore, the stirring speed in step (3) is 100 to 300 rpm.

[0050] Furthermore, the stirring and mixing time in step (3) is 30 to 60 minutes.

[0051] Furthermore, the stirring and mixing time in step (3) is 30 to 40 minutes.

[0052] Another object of the present invention is to disclose an application of low thermal stress liquid wax in the field of temporary wafer bonding.

[0053] The low thermal stress liquid wax of the present invention and its preparation method and application have the following advantages compared with the prior art:

[0054] 1) The present invention uses a covalent organic framework material as a filler, which has a two-dimensional structure with rigid channels. When heated in the in-plane direction, it exhibits negative expansion due to interlayer slippage and channel contraction, which can offset the positive expansion of the modified phenolic resin and reduce wafer warpage.

[0055] 2) The inorganic nanomaterials used in this invention can act as a secondary buffer layer, releasing local shear stress through nanoscale slip. The covalent organic framework (COF) and inorganic nanomaterials (such as nanosilica) work synergistically, and the inorganic nanomaterials (such as nanosilica) can be evenly dispersed in the interlayer spaces of the COF, thereby limiting the thermal motion of the liquid wax molecular chains, reducing interfacial stress concentration caused by thermal expansion differences, further reducing the overall thermal expansion coefficient, and avoiding wafer warpage caused by thermal expansion differences.

[0056] 3) The xylene-modified phenolic resin of the present invention has improved water resistance and alkali resistance due to the introduction of a hydrophobic xylene structure, and increased thermal stability, thereby further expanding the processing window of the low thermal stress liquid wax.

[0057] The low thermal stress liquid wax of the present invention has good application prospects and large-scale promotion potential in the field of temporary wafer bonding. DETAILED DESCRIPTION

[0058] The present invention will be further described below with reference to the following examples. The following description of the technical features is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0059] Unless otherwise stated, the units used in this specification are international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0060] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints A and B.

[0061] In this specification, the numerical range expressed using "above" or "below" means a numerical range including the number.

[0062] In this specification, the use of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

[0063] In this specification, the use of "optional" or "optional" indicates that certain substances, components, execution steps, application conditions and other factors are used or not used.

[0064] In this specification, when "normal temperature" or "room temperature" is used, the temperature may be 15-25°C.

[0065] In this manual, the reagents or instruments used without indicating the manufacturer are all conventional products that can be obtained through commercial purchase.

[0066] Examples 1-10

[0067] Examples 1-10 disclose a variety of low thermal stress liquid waxes, the components and weight ratios of which are shown in Table 1. The preparation methods thereof are as follows:

[0068] Step (1) The polar solvent, the non-polar solvent and the coupling agent are stirred at 275 rpm for 5 minutes to mix uniformly to obtain a solution.

[0069] Step (2) The solution obtained in step (1) is heated to 35° C., and tackifying resin and xylene-modified phenolic resin are added under continuous stirring at 275 rpm, and stirring is continued for 90 minutes until a clear and transparent liquid is formed to obtain a mixed solution.

[0070] Step (3) adding the inorganic nanomaterial and the covalent organic framework material to the mixed solution obtained in step (2) under stirring at 275 rpm, and continuing stirring for 40 minutes until the mixture is uniformly mixed to obtain a variety of low thermal stress liquid waxes.

[0071] Table 1 Components and ratios of low thermal stress liquid waxes of Examples 1-10

[0072]

[0073]

[0074] The xylene-modified phenolic resin is prepared by the following method:

[0075] Under the catalytic action of 1 part by mass of catalyst, 60 parts by mass of xylene formaldehyde resin, 200 parts by mass of phenol, 30 parts by mass of m-diphenol and 60 parts by mass of formaldehyde are reacted at 100°C for 30 minutes to complete the condensation reaction, 7 parts by mass of a terminator are added, and the temperature is raised to 180°C and maintained for 60 minutes for temperature distillation to distill out water and other volatile small molecules, thereby obtaining the xylene-modified phenolic resin (Mw=672).

[0076] The catalyst is dodecylbenzenesulfonic acid, and the terminator is sodium hydroxide.

[0077] Comparative Examples 1-5

[0078] Comparative Examples 1-5 disclose a variety of liquid waxes, the components and proportions of which are shown in Table 2, and the preparation methods thereof are the same as those of Example 1.

[0079] Table 2 Components and ratios of liquid waxes in comparative examples 1-5

[0080]

[0081]

[0082] The low thermal stress liquid waxes of Examples 1-10 and the liquid waxes of Comparative Examples 1-5 were tested respectively. The test methods and test results are as follows:

[0083] Table 3 Test results

[0084] performance Coefficient of thermal expansion CTE / K WARP / μm after waxing Example 1 <![CDATA[36×10 -6 ]]> 6.2 Example 2 <![CDATA[38×10 -6 ]]> 6.5 Example 3 <![CDATA[42×10 -6 ]]> 7.3 Example 4 <![CDATA[48×10 -6 ]]> 8.5 Example 5 <![CDATA[44×10 -6 ]]> 7.5 Example 6 <![CDATA[46×10 -6 ]]> 7.8 Example 7 <![CDATA[49×10 -6 ]]> 9.3 Example 8 <![CDATA[47×10 -6 ]]> 8.0 Example 9 <![CDATA[53×10 -6 ]]> 9.7 Example 10 <![CDATA[50×10 -6 ]]> 8.9 Comparative Example 1 <![CDATA[73×10 -6 ]]> 13.2 Comparative Example 2 <![CDATA[78×10 -6 ]]> 13.6 Comparative Example 3 <![CDATA[62×10 -6 ]]> 12.1 Comparative Example 4 <![CDATA[65×10 -6 ]]> 12.8 Comparative Example 5 <![CDATA[58×10 -6 ]]> 10.6

[0085] Based on Table 3, it can be seen that the low thermal stress liquid wax of the present invention has a low WARP value and a low thermal expansion coefficient, which effectively reduces wafer warpage.

[0086] However, the liquid wax in Comparative Example 1 lacks the covalent organic framework material COF-42, which results in an increased WARP value and wafer warpage;

[0087] Comparative Example 2 The liquid wax lacks the inorganic nanomaterial nano-silica, which results in an increased thermal expansion coefficient;

[0088] Comparative Example 3: The liquid wax uses calcium phosphate as a filler, which results in an increase in the thermal expansion coefficient;

[0089] Comparative Example 4: The liquid wax uses nano-alumina as a filler, which results in an increase in the thermal expansion coefficient;

[0090] The liquid wax of Comparative Example 5 uses unmodified phenolic resin as the base resin, resulting in an increase in WARP value and thermal expansion coefficient.

[0091] in:

[0092] Performance 1 The test method for the thermal expansion coefficient of liquid wax is:

[0093] Liquid wax was used for verification. 30 g of liquid wax was baked in an oven at 150°C for 2 h. The thermal expansion coefficient of the obtained solid was measured using a static thermomechanical analyzer (TMA). The test conditions were: heating rate 10°C / min; temperature range: room temperature to 300°C; load 50Mw, and nitrogen atmosphere.

[0094] Performance 2 WARP test method after waxing is:

[0095] Taking an 8-inch silicon wafer as an example, liquid wax was used for spin coating verification. The spin-coated silicon wafer was placed on a 140°C baking tray and baked for 30 seconds to evaporate the solvent. The dried silicon wafer was removed and a manual E+H tester was used to perform WARP measurement on the waxed silicon wafer.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low thermal stress liquid wax, characterized in that The composition comprises the following components in the following weight ratios:

2. The low thermal stress liquid wax according to claim 1, characterized in that The inorganic nanomaterial is one or more of nano silicon dioxide, nano silicon carbide and nano aluminum titanate.

3. The low thermal stress liquid wax according to claim 1, characterized in that The mass ratio of the covalent organic framework material to the inorganic nanomaterial is 1:1-10.

4. The low thermal stress liquid wax according to claim 1, characterized in that The modified phenolic resin is xylene-modified phenolic resin.

5. The low thermal stress liquid wax according to claim 4, characterized in that The xylene-modified phenolic resin is prepared by the following method: Under the action of a catalyst, xylene formaldehyde resin, phenol, m-diphenol and formaldehyde are mixed, reacted at 60-120° C. for 5-180 minutes, a terminator is added, and the temperature is raised to 100-200° C. and maintained for 30-180 minutes for distillation to obtain the xylene modified phenolic resin.

6. The low thermal stress liquid wax according to claim 5, characterized in that: The catalyst is C1-C 15 One or more of alkylbenzenesulfonic acids.

7. The low thermal stress liquid wax according to claim 5, characterized in that: The terminator is sodium hydroxide.

8. The low thermal stress liquid wax according to claim 1 or 4, characterized in that: The weight average molecular weight of the modified phenolic resin is 200-1000.

9. A method for preparing the low thermal stress liquid wax according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step (1) stirring and mixing a polar solvent, a non-polar solvent and a coupling agent to obtain a solution; Step (2) heating the solution obtained in step (1) to 30-50° C., adding a tackifying resin and a modified phenolic resin under stirring, stirring and mixing to obtain a mixed solution; Step (3) adds inorganic nanomaterials and covalent organic framework materials to the mixed solution obtained in step (2) under stirring conditions, and stirs and mixes to obtain low thermal stress liquid wax.

10. Use of the low thermal stress liquid wax according to any one of claims 1 to 8 in the field of temporary wafer bonding.

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