Wafer temporary bonding material and preparation method and application thereof

Abstract

The invention provides a temporary wafer bonding material and a preparation method and application thereof. The temporary wafer bonding material comprises the following components in parts by weight: 25-35 parts of matrix resin; 2-5 parts of a functional plasticizer; and 35-73 parts of a compound solvent system. The temporary wafer bonding material solves the problems that an existing material is poor in acetone resistance and unstable in preparation process.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing and packaging materials technology, and relates to a wafer temporary bonding material, its preparation method and application. Background Technology

[0002] As integrated circuits evolve towards ultra-thin and three-dimensional stacking (3D-IC), wafer thickness continues to decrease, typically needing to be reduced to 100μm or even below 50μm. In this process, temporary bonding / debonding (TBDB) technology plays a crucial supporting role.

[0003] Currently, temporary bonding materials mostly employ thermoplastic polymer systems. However, in actual manufacturing processes, wafers often need to undergo harsh chemical environments. For example, during photoresist stripping, residual photoresist cleaning, or certain wet etching steps, the wafer edges are in prolonged contact with highly polar organic solvents, such as acetone and N-methylpyrrolidone (NMP).

[0004] The existing technology has the following main drawbacks: 1. Poor solvent resistance: Traditional rosin-based or acrylic-based bonding adhesives are highly oleophilic and easily swell or dissolve in acetone. This can lead to "lateral undercut" at the bonding layer edges, where chemicals seep into the wafer front along the undercut channels, corroding the device and even causing the wafer to break during high-speed rotation or grinding.

[0005] 2. Low process stability: Existing polyamide materials are generally difficult to dissolve in alcohol solvents, requiring heating to above 80°C during preparation. High-temperature production not only consumes a lot of energy and poses significant safety risks, but also leads to the volatilization loss of low-boiling-point components (such as isopropanol) in the mixed solvent, causing batch-to-batch fluctuations in solid content, ultimately making it impossible to accurately control the coating thickness (TTV) at the user end.

[0006] Therefore, developing a temporary bonding material with strong component anti-extraction ability, synergistic solubilizing effect of solvent system, and stable preparation at room temperature is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a temporary wafer bonding material, its preparation method, and its applications. The temporary wafer bonding material of the present invention solves the problems of poor acetone resistance and unstable preparation processes of existing materials.

[0008] To achieve this objective, the present invention adopts the following technical solution: On one hand, the present invention provides a wafer temporary bonding material, the wafer temporary bonding material comprising the following components in parts by weight: Main resin: 25-35 parts; Functional plasticizer: 2-5 parts; Compound solvent system: 35 ~ 73 parts.

[0009] In this invention, the problems of poor acetone resistance and unstable preparation process of existing materials are solved by using functional plasticizers and compound solvent systems.

[0010] In this invention, the amount of the main resin system in the wafer temporary bonding material can be 25 parts, 28 parts, 30 parts, 33 parts or 35 parts, the amount of the functional plasticizer can be 2 parts, 3 parts, 4 parts or 5 parts, etc., and the amount of the compound solvent system can be 35 parts, 39 parts, 43 parts, 47 parts, 51 parts, 55 parts, 59 parts, 63 parts, 67 parts or 73 parts, etc.

[0011] Preferably, the main resin is an alcohol-soluble polyamide resin.

[0012] Preferably, the main resin is an alcohol-soluble polyamide resin with a softening point between 120°C and 160°C (e.g., 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, or 160°C). This type of resin contains a large number of amide groups (-CONH-) in its molecular chain, and the strong intermolecular hydrogen bonds formed by them give the material natural solvent resistance. At the same time, an appropriate amount of long-chain hydrophobic groups ensures its solubility in specific alcohol solvents.

[0013] Preferably, the functional plasticizer comprises any one or a combination of at least two of the following compounds: phosphate esters, benzenesulfonamides, long-chain diesters, or polyesters.

[0014] Preferably, the functional plasticizer has anti-solvent extraction properties and is preferably a condensation-type phosphate ester or long-chain alkylbenzene sulfonamide with a molecular weight greater than 500 (e.g., 510, 530, 550, 570, 600, 650, 680, 700, etc.).

[0015] Preferably, the functional plasticizer is selected from one or a combination of at least two of resorcinol bis(diphenyl phosphate), bisphenol A bis(diphenyl phosphate), N-butylbenzenesulfonamide or N-ethyl o- / p-toluenesulfonamide.

[0016] Preferably, the compound solvent system contains at least two organic solvents with different evaporation rates, wherein the organic solvents are selected from any one or a combination of at least two of the following: low-carbon alcohols, aromatic alcohols, ether esters or ketone solvents.

[0017] Preferably, the compound solvent system consists of a main solvent and a co-solvent.

[0018] Preferably, the main solvent is selected from at least one of ethanol, isopropanol, n-propanol, or n-butanol.

[0019] Preferably, the co-solvent is selected from at least one of benzyl alcohol, propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), or cyclohexanone.

[0020] Preferably, the mass ratio of the main solvent to the co-solvent is 8:2 to 9:1, such as 8:2, 8.5:1.5, or 9:1. To achieve room temperature dissolution and high leveling properties, the compound solvent system is preferably a mixture of isopropanol and benzyl alcohol, or a mixture of isopropanol and propylene glycol monomethyl ether acetate.

[0021] On the other hand, the present invention provides a method for preparing a wafer temporary bonding material as described above, the method comprising the following steps: The main resin system and functional plasticizer are added to the compound solvent system and mixed to obtain the wafer temporary bonding material.

[0022] Preferably, the mixing process involves high-speed shearing to swell and dissolve the resin in a solvent to form a homogeneous solution. After the system reaches a homogeneous state, it is filtered by a filtration device, degassed under vacuum, and then filled into the container.

[0023] Preferably, the compound solvent system is obtained by uniformly mixing the main solvent and the co-solvent.

[0024] Preferably, the mixing of the main solvent and the co-solvent is carried out under stirring, and the stirring rate is controlled between 50-200 rpm, such as 50 rpm, 100 rpm, 150 rpm, 200 rpm, etc., but not limited to the listed values; other unlisted values ​​within this range are also applicable. The stirring time is 10-20 min, such as 10 min, 12 min, 15 min, 18 min, 20 min, etc., but not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0025] Preferably, the addition of the main resin system and the functional plasticizer to the compound solvent system is carried out under stirring. The stirring rate is controlled at 400-1000 rpm, such as 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable. The stirring time is 1-4 h, such as 1 h, 2 h, 3 h, 4 h, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0026] Preferably, the filtration is performed using a filter element with a diameter 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.).

[0027] On the other hand, the application of the wafer temporary bonding material described in this invention in temporary bonding.

[0028] Compared with the prior art, the present invention has the following beneficial effects: (1) The wafer temporary bonding material of the present invention has high chemical corrosion resistance and creatively introduces high molecular weight, high steric hindrance modifiers, such as polycondensation phosphate esters (e.g., resorcinol bis(diphenyl phosphate)) or long-chain sulfonamides. These molecules can not only effectively reduce the crystallinity of polyamides and give the material the toughness required in the thinning process; more importantly, due to their large molecular volume and strong structural rigidity, acetone molecules have difficulty displacing them from the resin network.

[0029] (2) This invention employs a combination strategy of "main solvent (good solvent) + co-solvent (swelling agent / high-boiling-point solvent)". The main solvent (such as isopropanol) rapidly enters the polymer chain segment and completes dissolution, while the co-solvent (such as benzyl alcohol or PGMEA) increases the solubility of the functional plasticizer. This synergistic effect of binary or multi-component solvents enables the invention to achieve rapid dissolution at room temperature of 15-35℃, completely avoiding the uncontrollable solvent volatilization problem caused by high-temperature preparation. At the same time, the high-boiling-point characteristics of the co-solvent ensure the leveling properties during spin coating and baking, achieving low TTV. Detailed Implementation

[0030] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0031] The raw materials used in the following examples are as follows: Main resin A: Non-alcohol-soluble polyamide resin, amine value ≤ 5 mgKOH / g, model HY408.

[0032] Main resin B: Alcohol-soluble polyamide resin, softening point 135℃, amine value ≤5 mgKOH / g, model HY508.

[0033] Main resin C: Alcohol-soluble acrylic resin, model SR862; Plasticizer P1: Resorcinol bis(diphenyl phosphate) (condensation phosphate).

[0034] Plasticizer P2: N-Butylbenzenesulfonamide (BBSA).

[0035] Plasticizer P3: Dioctyl phthalate (DOP).

[0036] Solvent S1: Isopropanol (IPA).

[0037] Solvent S2: Benzyl Alcohol.

[0038] Solvent S3: Propylene glycol monomethyl ether acetate (PGMEA).

[0039] Examples 1-5 and Comparative Examples 1-2 The formulation of the temporary wafer bonding material in this embodiment is shown in Table 1. The preparation process of the temporary wafer bonding material is as follows: In a clean environment at 25°C and 45% relative humidity, the solvent is mixed in proportion, added to the resin, and dispersed at high speed (800 rpm) for 3-4 hours until completely dissolved and transparent. Then, the plasticizer is added and stirred at low speed for 30 minutes, and filtered through a 0.5μm filter.

[0040] Table 1 Note: Unit: weight percentage (wt.%); "—" indicates no addition or <0.1%.

[0041] The total for each column is 100; there may be rounding errors in some columns (≤±0.5).

[0042] Performance testing methods and results Sample preparation: The adhesive was spin-coated onto a 4-inch silicon wafer and baked to cure (120℃ / 3min + 160℃ / 3min), with the film thickness controlled at 10μm. The wax-coated and dried silicon wafer was then stacked face-to-face with a glass substrate and aligned in a bonding machine. The wafer was then pressed at 140℃ and 1kN for 5 minutes. Finally, it was cooled while maintaining pressure to obtain the bonded pair.

[0043] Acetone resistance test (quantitative): The bonded wafer pair is completely immersed in an analytical grade acetone solution at 25°C.

[0044] Corrosion depth (L): After soaking for 1 hour and 4 hours respectively, the lateral distance (unit: μm) at which the edge adhesive layer dissolves, turns white or detaches is measured under an optical microscope.

[0045] TTV test: The adhesive was spin-coated onto a 4-inch silicon wafer using a spin coater at a speed of 1200 rpm for 30 seconds. After baking and curing, the thickness difference at 9 points was measured using a film thickness gauge.

[0046] The performance test results are shown in Table 2.

[0047] Table 2 Results analysis: Comparative Example 5 used only isopropanol (IPA) as a single solvent. Experiments showed that after 24 hours of continuous stirring at room temperature, the resin components remained in a white suspension, failing to dissolve effectively, demonstrating that IPA's dissolving power for this resin system was insufficient. Example 2, however, introduced 10% by mass of benzyl alcohol as an auxiliary solvent. Benzyl alcohol has better solubility for plasticizer molecules and a unique strong swelling ability in amorphous regions of polymers. Its addition effectively "opens" the entanglement structure between polymer chains, forming solvent diffusion channels, allowing IPA to rapidly penetrate and dissolve the resin, ultimately achieving a rapid "flash dissolution" effect at room temperature. Furthermore, the total thickness variation (TTV) of the film obtained in Example 2 was only 0.5 μm, superior to other comparative examples. The results demonstrate that the use of the "benzyl alcohol-IPA" mixed solvent system and the specific evaporation gradient (approximately 9:1) in this embodiment can effectively regulate the solvent evaporation rate during spin coating and baking, avoiding local turbulence or uneven film shrinkage caused by excessively rapid evaporation. This greatly promotes the leveling properties of the adhesive, ultimately resulting in a coating with excellent smoothness and surface quality, and avoiding defects such as orange peel.

[0048] Example 2 (using phosphate ester plasticizer P1) and Comparative Example 6 (using dioctyl phthalate DOP) used the same solvent system, and their initial film quality and smoothness were similar. However, in subsequent solvent resistance tests, they showed significant differences: after immersing the adhesive layer of Comparative Example 6 in acetone for 1 hour, the edge corrosion depth exceeded 150 μm; after immersion for 4 hours, the adhesive layer turned white and showed brittle cracking. Analysis showed that DOP has a small molecular weight, moderate polarity, and a very strong affinity for acetone. Since it mainly exists in a "free state" in the polyamide resin network, acetone molecules easily extract and migrate it from the adhesive layer. Once the plasticizer is lost, the polyamide network regains its intrinsic brittleness and induces microcracks, thereby accelerating the penetration and destruction of acetone.

[0049] In contrast, the plasticizer P1 used in Example 2 has a significantly higher molecular weight, and its molecular structure contains a rigid framework of biphenyl rings and phosphate esters, exhibiting a significant steric hindrance effect. This plasticizer can firmly embed itself between polyamide molecular chains like an "anchor," making it difficult for acetone molecules to effectively displace or extract it. Experimental data show that after immersion in acetone for 4 hours, the corrosion depth of its adhesive layer is less than 70 μm, demonstrating excellent solvent resistance.

[0050] Example 3 used a sulfonamide plasticizer (P2). Although its corrosion resistance was slightly inferior to that of phosphate esters (corrosion depth <80μm), it was still far superior to traditional materials, indicating that the "anti-extraction modified system" proposed in this invention has broad applicability. To further explore the optimal ratio of the "benzyl alcohol-IPA" mixed solvent system, Comparative Examples 3 and 4 were adjusted to solvent ratios of 7:3 and 9.5:0.5, respectively. The results showed slight turbidity after dissolution, proving that the dissolving ability of the mixed solvent was limited at these corresponding ratios. Example 1 adjusted the solvent ratio to 8:2. Although the dissolution effect and film-forming properties remained excellent, the TTV was slightly higher than that of Example 2, indirectly confirming the uniqueness of the 9:1 ratio (but within the scope of patent protection, 8:2 remains the protected preferred solution).

[0051] Furthermore, Comparative Example 2 shows that when other alcohol-soluble main resins (such as acrylic resin) are used, their corrosion degree (>1000μm) after immersion in acetone solution for one hour is much greater than that of alcohol-soluble polyamide resin. Under longer exposure time (4h), large areas of whitening appear on the bonded surface. This result demonstrates the key role and indispensability of alcohol-soluble polyamide resin in resisting corrosion by acetone solvent.

[0052] Comparative Example 1 used a non-alcohol-soluble polyamide resin, which resulted in very poor solubility at room temperature, making it impossible to conduct subsequent experiments and performance tests.

[0053] The applicant declares that this invention illustrates the wafer temporary bonding material, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

Claims

1. A wafer temporary bonding material, characterized in that, The wafer temporary bonding material comprises the following components in parts by weight: Main resin: 25-35 parts; Functional plasticizer: 2-5 parts; Compound solvent system: 40-73 parts.

2. The wafer temporary bonding material according to claim 1, characterized in that, The main resin is an alcohol-soluble polyamide resin; Preferably, the main resin is an alcohol-soluble polyamide resin with a softening point between 120°C and 160°C.

3. The wafer temporary bonding material according to claim 1 or 2, characterized in that, The functional plasticizer comprises any one or a combination of at least two of the following: phosphate esters, benzenesulfonamides, long-chain diesters, or polyester compounds; Preferably, the functional plasticizer has anti-solvent extraction properties and is preferably a condensation-type phosphate ester or a long-chain alkylbenzene sulfonamide with a molecular weight greater than 500. Preferably, the functional plasticizer is selected from one or a combination of at least two of resorcinol bis(diphenyl phosphate), bisphenol A bis(diphenyl phosphate), N-butylbenzenesulfonamide or N-ethyl o- / p-toluenesulfonamide.

4. The wafer temporary bonding material according to any one of claims 1-3, characterized in that, The compound solvent system contains at least two organic solvents with different evaporation rates, wherein the organic solvents are selected from any one or a combination of at least two of the following: low-carbon alcohols, aromatic alcohols, ether esters or ketones.

5. The wafer temporary bonding material according to any one of claims 1-4, characterized in that, The compound solvent system consists of a main solvent and a co-solvent; Preferably, the main solvent is selected from at least one of ethanol, isopropanol, n-propanol, or n-butanol; Preferably, the co-solvent is selected from at least one of benzyl alcohol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, or cyclohexanone.

6. The wafer temporary bonding material according to any one of claims 1-5, characterized in that, The mass ratio of the main solvent to the co-solvent is 8:2 to 9:

1.

7. The wafer temporary bonding material according to any one of claims 1-6, characterized in that, The preferred compound solvent system is a mixture of isopropanol and benzyl alcohol, or a mixture of isopropanol and propylene glycol monomethyl ether acetate.

8. The method for preparing the wafer temporary bonding material according to any one of claims 1-7, characterized in that, The preparation method includes the following steps: The main resin system and functional plasticizer are added to the compound solvent system and mixed to obtain the wafer temporary bonding material.

9. The preparation method according to claim 8, characterized in that, The mixing process involves high-speed shearing, which causes the resin to swell and dissolve in the solvent to form a homogeneous solution. After the system reaches a homogeneous state, it is filtered by a filtration device, degassed under vacuum, and then filled. Preferably, the compound solvent system is obtained by uniformly mixing the main solvent and the co-solvent. Preferably, the mixing of the main solvent and the co-solvent is carried out under stirring, the stirring rate is controlled at 50-200 rpm, and the stirring time is 10-20 min; Preferably, the mixing of the main resin system and functional plasticizer into the compound solvent system is carried out under stirring, the stirring rate is controlled at 400-1000 rpm, and the stirring time is 1-4 h; Preferably, the filtration is performed using a filter element with a diameter of 0.2-1.0 μm.

10. The use of the wafer temporary bonding material according to any one of claims 1-7 in temporary bonding.

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