DE212015000125U1 - Temporary adhesive adhesive for processing a thin wafer - Google Patents

Abstract

A temporary adhesive agent for thin wafer processing, characterized by comprising, based on 100 parts of the total adhesive temporary adhesive amount, 55 to 70 parts of solvent and 30 to 45 parts of base resin dissolved or dispersed in the solvent, and the base resin is a high polymer or a high polymer mixture having a thermal decomposition temperature of 320 ° C or higher.

Description

Technical area

The present invention relates to the field of adhesives, more particularly to temporary adhesive adhesives for thin wafer processing.

background

In recent years, the demands on the microelectronic presentation of computers, communication devices, vehicle electronics and other consumer products have increased, that is, it is desired that the microelectronic presentation of these products be smaller, thinner, multifunctional, and inexpensive. To meet the demand for miniaturization of these products, device wafers must be thinned to 100 μm or less in the semiconductor industry. Ultrathin wafers have characteristics of flexibility and fragility, are easy to buckle, and easily generate waves, etc. Therefore, in general, a device wafer is first adhered to a thicker substrate using a temporary adhesive material and then thinned at its backside and made a redistribution layer and to form a bond, the adhesive layer is treated to lessen in efficiency by supplying external energy (light, electricity, heat and external force), after which the device wafer is separated from the carrier. This process is a temporary bonding process for a wafer. Here, the temporary tacky adhesive used to fix the thin wafer is critical to the success of the temporary bonding process.

The Chinese patent CN104130727A discloses a pressure-sensitive temporary tacky adhesive whose raw materials comprise 30 to 70 parts solvent, 30 to 50 parts base resin, 5 to 30 parts microencapsulated particles, and also one of tackifiers, low molecular weight cycloolefin copolymers, plasticizers, antioxidants or a mixture of two or more thereof, wherein the base resin is cycloolefin polymer particles; the solvent is one of cyclododecene, bicyclohexene, limonene, mesitylene, cyclopentanone, methylcyclohexane, methyl ethyl ketone, dipentene, cyclooctane, butylcyclohexane, cycloheptane and cyclohexane, or a mixture of two or more thereof; the structure of the microencapsulated particles is composed of a core of a macromolecular compound and an outer layer of a continuous wall or external phase of a natural or synthetic macromolecular compound. The Chinese patent CN102203917A discloses a composition used for temporary wafer bonding and composed of free tackifiers, low molecular weight cycloolefin copolymers, plasticizers and antioxidants, the tackifier being selected from polyterpene resins, beta-polyterpene resins, styrene-terpene resins, polymerized rosin resins, rosin ester resins, cyclo-aliphatic hydrocarbon resins C ₅ aliphatic hydrocarbon resins, hydrogenated hydrocarbon resins; wherein the low molecular weight cycloolefin copolymer has a weight average molecular weight of less than about 50,000 daltons. In the above prior art, the temporary adhesive adhesive still has defects of low thermal stability and poor corrosion resistance.

Content of the invention

In view of the problems in the prior art, it is an aspect of the present invention to provide a temporary adhesive adhesive having high thermal stability and excellent corrosion resistance.

A temporary adhesive agent for thin wafer processing is characterized by comprising, based on 100 parts of the total adhesive temporary adhesive, 55 to 70 parts of solvent and 30 to 45 parts of base resin dissolved or dispersed in the solvent, and the base resin High polymer or a high polymer mixture having a thermal decomposition temperature of 320 ° C or higher.

In the above-mentioned temporary adhesive agent, the base resin having a heat decomposition temperature of 320 ° C. or higher ensures that the adhesive layer formed by the temporary adhesive adhesive has good thermal stability. The base resin has a weight average molecular weight of 5 × 10 ³ ~ 5 × 10 ⁵ and a melt index of 24 or greater. Specific examples of the high polymer are polyhydrocarbyl acrylates, polyphenyl ethylenes and polyesters.

in dessen molekularer Struktur umfasst, wobei R₁ ein C_1~2 aliphatischer oder aromatischer Kohlenwasserstoff ist, R₂ ein C_1~3 aliphatischer oder aromatischer Kohlenwasserstoff ist, zum Beispiel Poly(methylmethacrylat). Wenn R₁ ein Kohlenstoffatom aufweist und R₂ ein Kohlenstoffatom aufweist (d. h. es ist PMMA), ist die Glasübergangstemperatur Tg 105°C; wenn R₁ zwei Kohlenstoffatome aufweist und R₂ ein Kohlenstoffatom aufweist (d. h. es ist PEMA), ist der Tg 65°C; wenn R₁ vier Kohlenstoffatome aufweist und R₂ ein Kohlenstoffatom aufweist (d. h. es ist PBMA), ist der Tg 20°C, und es weist eine niedrige thermische Zersetzungstemperatur (lediglich 220°C) in Luft auf. Mit dem Anstieg der Anzahl an Kohlenstoffatomen in R₁ steigt die Flexibilität des Polymers, der Tg wird niedriger und niedriger, und eine viskose Strömungstemperatur (T_f) wird auch abnehmen. Falls die T_f zu niedrig ist, wird die Betriebstemperatur des temporären Klebehaftmittels beeinträchtigt. Die Anzahl an Kohlenstoffatomen von R₂ ist bevorzugt 1–3, und R₂ kann ein aromatischer Kohlenwasserstoff sein. Es ist beachtenswert, dass die Anzahl an Kohlenstoffatomen in R₂ nicht weniger als 1 sein kann. Wenn R₂ kein Kohlenstoffatom aufweist, wird der Tg des erhaltenen Methylacrylats zu niedrig (lediglich 6°C). The high polymer is a polyhydrocarbyl acrylate which is a homopolymer or copolymer which is a repeating unit

in its molecular structure, wherein R _{1 is} a C _1-2 aliphatic or aromatic hydrocarbon, R _{2 is} a C _1-3 aliphatic or aromatic hydrocarbon, for example poly (methyl methacrylate). When R _{1 has} a carbon atom and R _{2 has} a carbon atom (ie, it is PMMA), the glass transition temperature Tg is 105 ° C; when R _{1 has} two carbon atoms and R _{2 has} one carbon atom (ie it is PEMA), the Tg is 65 ° C; when R _{1 has} four carbon atoms and R _{2 has} one carbon atom (ie, it is PBMA), the Tg is 20 ° C and has a low thermal decomposition temperature (only 220 ° C) in air. As the number of carbon atoms in R ₁ increases, the flexibility of the polymer increases, the Tg becomes lower and lower, and a viscous flow temperature (T _f ) will also decrease. If the T _{f is} too low, the operating temperature of the temporary adhesive adhesive is impaired. The number of carbon atoms of R ₂ is preferably 1-3, and R ₂ may be an aromatic hydrocarbon. It is noteworthy that the number of carbon atoms in R ₂ can not be less than 1. When R _{2 has} no carbon atom, the Tg of the obtained methyl acrylate becomes too low (only 6 ° C).

in deren molekularen Strukturen umfassen, wobei R₁ und R₂ bevorzugt C_1~3 aliphatische oder aromatische Kohlenwasserstoffe sind. Wenn sowohl R₁ als auch R₂ aliphatische Kohlenwasserstoffgruppen sind, wird das gebildete Olefinpolymer einerseits aufgrund der Abwesenheit von Seitenkettengruppen in dessen molekularer Struktur einen niedrigen Tg aufweisen und andererseits einfach zu kristallisieren sein (zum Beispiel PE, PP und PMP weisen alle eine hohe Kristallinität auf), was dessen Eigenschaften zur Verwendung als ein Basisharz für Klebematerialien beeinträchtigen kann. Falls die aliphatische Kohlenwasserstoffkette zu lang ist, wird die Flexibilität des Polymers steigen und dadurch wird der Tg abnehmen, was die Betriebstemperatur eines Klebehaftmittels beeinträchtigen wird.Polyphenylethylenes are homopolymers or copolymers which are a repeat unit

in their molecular structures, wherein R ₁ and R _{2 are} preferably C _{1 ~ 3} aliphatic or aromatic hydrocarbons. On the one hand, when both R ₁ and R _{2 are} aliphatic hydrocarbon groups, the olefin polymer formed will have a low Tg due to the absence of side chain groups in its molecular structure and, on the other hand, be easy to crystallize (for example, PE, PP and PMP all have high crystallinity ), which may affect its properties for use as a base resin for adhesive materials. If the aliphatic hydrocarbon chain is too long, the flexibility of the polymer will increase and thereby the Tg will decrease, which will affect the operating temperature of an adhesive adhesive.

in deren molekularen Strukturen aufweisen, wobei R Cyclohexyl, Phenyl oder Hexyloxy ist, das heißt

Hierbei können die Polyester als ein physikalisches Gemisch der drei Polyester A, B und C ausgewählt werden. Die Massengehalte an A, B und C sind 10–60%, 10–80% bzw. 0–50% und die Molekulargewichte von A, B und C sind 8000–30000, 5000–50000 bzw. 5000–100000.Polyesters are homopolymers or copolymers which are a repeat unit

in which have molecular structures, wherein R is cyclohexyl, phenyl or hexyloxy, that is

Here, the polyesters may be selected as a physical mixture of the three polyesters A, B and C. The mass contents of A, B and C are 10-60%, 10-80% and 0-50% and the molecular weights of A, B and C are 8000-30000, 5000-50000 and 5000-100000, respectively.

It is noteworthy that, for example, the high polymer blend may be one or more of polyhydrocarbyl acrylates, one or more of polyphenylethylenes, one or more of polyesters, and may also be a blend of one (1) polyhydrocarbyl acrylate and one (1) polyphenylethylene, or a mixture of one (1) polyhydrocarbyl acrylate and one (1) polyester, etc. As one embodiment, for example, polyacrylate having a molecular weight of from 5,000 to 30,000,000 and poly (α-methylstyrene) having a molecular weight of from 3,000 to 20,000 may be used Mass ratio is 2: 1-20: 1.

The solvent has a boiling point preferably higher than 80 ° C and a polarity similar to that of the corresponding polymer. The solvent may be, for example, one or at least two of propylene glycol monomethyl ether acetate, dimethylacetamide, propylene glycol monomethyl ether, ethyl lactate, limonene, mesitylene, cyclododecene and cyclopentanone.

Further, the temporary adhesive adhesive, based on 100 parts of the total adhesive temporary adhesive, further comprises 0.05 to 0.07 parts of leveling agent and 0 to 0.15 parts of antioxidant.

Here, the leveling agent is preferably a fluorine-modified acrylate leveling agent. The antioxidant is preferably composed of a polybasic hindered phenol antioxidant as a primary antioxidant and phosphite antioxidant as a secondary antioxidant, and compounding of the two components results in improving the thermal stability of the adhesive adhesive.

With respect to the above temporary adhesive adhesive, a preferred formulation is that they contain 20 to 30 parts PMMA, 10 to 15 parts poly (α-methylstyrene), 55 to 70 parts solvent, and 0.05-0.07 parts FC-4430 type leveling agent includes; more preferably, it comprises 24 parts PMMA, 12 parts poly (α-methylstyrene), 64.95 parts DMAc, and 0.05 part FC-4430 type leveling agent.

In another aspect, the present invention provides a process for producing a temporary adhesive adhesive, with which a temporary adhesive adhesive having high thermal stability and excellent corrosion resistance can be obtained.

A method for producing a temporary adhesive adhesive as mentioned above comprises the steps of mixing 30 to 45 parts of base resin, 55 to 70 parts of solvent, and 0.05-0.07 part of leveling agent under heating and stirring conditions, followed by cooling and degassing after which a temporary adhesive adhesive is obtained.

With respect to the above method, heating is carried out at 60-70 ° C in a water bath; stirring is performed at a speed of 100-1000 rpm. carried out with mechanical stirring; and the degassing is carried out by vacuum degassing using a vacuum degasser.

In a further aspect, the present invention provides a method of bonding thin wafers which utilizes the above temporary tacky adhesive with good thermal stability and excellent corrosion resistance.

A method of bonding thin wafers using the above-described temporary adhesive specifically includes the steps of spin-coating the temporary adhesive adhesive onto a surface of a carrier wafer, drying the solvent and then covering the surface with a device wafer, followed by heating the temporary adhesive adhesive to the melt and then cooling the temporary adhesive adhesive to form an adhesive layer.

With respect to the above adhesive method, the heating of the temporary adhesive adhesive may be performed by a firing method. The other surface of the carrier wafer, which is not coated with the adhesive adhesive, can be baked directly. During the process of heating the adhesive adhesive, first, the solvent in the adhesive adhesive is evaporated, and with continued heating, the base resin slowly melts at about 200 ° C, then it is cooled and hardened to form an adhesive layer, whereby an adhesive effect between the carrier wafer and the adhesive Device wafer occurs. The procedure further comprises cleaning the adhesive layer residue on the environment of the device wafer using DMAc after an adhesive layer is formed by curing. Similarly, during the process of releasing the device wafer, DMAc may be used as a cleaning agent for dissolving the adhesive layer.

The temporary adhesive adhesive of the present invention comprises, based on 100 parts of the total adhesive temporary adhesive composition, 55 to 70 parts of solvent and 30 to 45 parts of base resin dissolved or dispersed in the solvent. The base resin is a high polymer or a high polymer mixture having a thermal decomposition temperature of 320 ° C or higher and a melt index of 24 or greater. As a result, the temporary tacky adhesive has advantages of good thermal stability and excellent corrosion resistance, and also has high adhesive / peeling efficiency. In addition, the adhesive layer residue is easy to clean and the cost of making the temporary adhesive adhesive is economical.

Brief description of the drawings

1 Fig. 15 shows a thermal gravimetric analysis curve of a dried coating film of the temporary adhesive adhesive according to Example 1 of the present invention;

2 Fig. 12 is a thermal gravimetric analysis curve of a dried coating film of the temporary adhesive adhesive according to Example 2 of the present invention;

3 shows a viscosity curve of the temporary adhesive adhesive after the solvent is removed as a function of the temperature;

4 shows a thickness distribution of a dried coating film of the temporary adhesive adhesive according to Example 2 of the present invention;

5 FIG. 12 shows an ultrasonic scanning micrograph after wafers are bonded by the temporary adhesive adhesive of Example 2 of the present invention. FIG.

embodiments

Hereinafter, the technical solutions of the present invention will be further described in combination with the drawings and the specific examples.

example 1

2.4 g poly (methyl methacrylate), 1.2 g poly (α-methylstyrene), 5 mg FC-4430 leveling agent and 6.335 g DMAc are added to a hot solution kettle equipped with a stirrer and a water bath heating system. The temperature of the water bath is controlled to 6070 ° C and the stirring apparatus is turned on and set to a speed of 100-1000 rpm. Has. The above raw materials are taken out after being completely mixed and are naturally cooled and then degassed under vacuum in a vacuum degasser, and finally sealed and stored.

Example 2

In this example, the raw materials specifically comprise 4 g of self-made polyester, 5 mg of 4430-type leveling agent, 5.995 g of PGMEA solvent; and they are stirred at room temperature for 1 hour.

Except for the preceding conditions, this example is the same as Example 1.

Example 3

In this example, the raw materials specifically include 2.0 g of poly (methyl methacrylate), 1.0 g of poly (α-methylstyrene), 5 mg of FC-4430 type leveling agent, 5.5 g of DMAc.

Except for the preceding conditions, this example is the same as Example 1.

Example 4

In this example, the raw materials specifically include 3.0 g of poly (methyl methacrylate), 1.5 g of poly (α-methylstyrene), 7 mg of FC-4430 type leveling agent, 7.0 g of DMAc.

Except for the preceding conditions, this example is the same as Example 1.

The corrosion resistance test results of Examples 1 and 2 are shown in Table 1 and Table 2 (since the specific test methods are well known to a person skilled in the art, these test methods are not described in detail). Table 1 Chemicals and test conditions chemicals Temperature / ° C Time / min. Results acetone 25 25 no peeling NMP 85 60 no peeling 6N HCl 60 30 no peeling 15% H ₂ O ₂ 60 40 no peeling 30% KOH 85 60 no peeling 70% ENT ₃ 25 60 no peeling EtOH 25 5 no peeling MeOH 25 5 no peeling IPA 25 5 no peeling ethyl lactate 25 5 no peeling PGME 25 5 no peeling Table 2 Chemicals and test conditions chemicals Temperature / ° C Time / min. Results acetone 25 25 no peeling NMP 85 60 no peeling 6N HCl 60 30 no peeling 15% H ₂ O ₂ 60 40 no peeling 30% KOH 85 60 no peeling 70% ENT ₃ 25 60 no peeling EtOH 25 5 no peeling MeOH 25 5 no peeling IPA 25 5 no peeling ethyl lactate 25 5 no peeling PGME 25 5 no peeling

As in 1 and 2 showing the TGA curves according to Examples 1 and 2 respectively, the dry films start to lose weight at 300 ° C and have a weight loss rate of 80%, ie the majority of the films decompose at 450 ° C. This indicates that the temporary adhesive adhesive of the present invention has good thermal stability.

As in 3 which shows a viscosity curve of the temporary adhesive adhesive of Example 1, the overall change in viscosity with temperature is moderate. This indicates that the temporary tacky adhesive of the present invention has good viscosity stability.

As in 4 which shows a thickness distribution of a dry coating film of the temporary tacky adhesive according to Example 2 of the present invention, the thickness of the temporary tacky adhesive coating is uniform, and its average thickness is 22.7 μm with a standard deviation of 0.5. This indicates that the adhesive layer has an appropriate thickness and is very smooth, and thereby has a good coating effect, and therefore the conditions for a coating process will not be severe.

As in 5 10, which shows an ultrasonic scanning micrograph after wafers are bonded by the temporary adhesive adhesive according to Example 2 of the present invention, the adhesive layer between the two bonded silicon wafers has no gap (no white dots) and is evenly distributed.

Although the numerical ranges of each parameter involved in the present invention may not be fully reflected in the above examples, those skilled in the art can understand that any value falling within the above numerical ranges includes any combination of specific values in FIG numerical ranges, the present invention can realize. Here, due to limited space, examples that show specific values in one or more numerical ranges are omitted, and this should not be construed as lending the propositions of the formula and process a support claimed in the present invention ,

The Applicant explains: the present application illustrates the detailed process equipment and the technological process of the present invention by the above examples, but the present invention is not limited to the detailed process equipment and the technological process, that is, it does not mean that the invention with Reference must be made to the above detailed process equipment and the technological process. One skilled in the art should understand that any modification of the present invention, any equivalent substitution of each of the raw materials of the present invention, and the addition of an adjuvant, selection of a specific embodiment, and the like, are within the scope and disclosure of the present invention.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• CN 104130727 A [0003]
• CN 102203917 A [0003]

Claims (6)

A temporary adhesive agent for thin wafer processing, characterized by comprising, based on 100 parts of the total adhesive temporary adhesive amount, 55 to 70 parts of solvent and 30 to 45 parts of base resin dissolved or dispersed in the solvent, and the base resin is a high polymer or a high polymer mixture having a thermal decomposition temperature of 320 ° C or higher. Temporary adhesive adhesive according to claim 1, characterized in that the high polymer is polyhydrocarbyl acrylate which is a homopolymer or copolymer which is a repeating unit

in its molecular structure, wherein R _{1 is} a C _1-2 aliphatic or aromatic hydrocarbon, R _{2 is} a C _1-3 aliphatic or aromatic hydrocarbon; or that the high polymer is polyphenylethylene which is a homopolymer or copolymer which is a repeating unit

in its molecular structure, wherein R ₁ and R _{2 are} preferably C _{1 ~ 3} aliphatic or aromatic hydrocarbons; or that the high polymer is polyester which is a homopolymer or copolymer which is a repeating unit

in its molecular structure, wherein R is cyclohexyl, phenyl or hexyloxy. Temporary adhesive adhesive according to claim 2, characterized in that the high polymer mixture is a mixture of at least two of polyhydrocarbyl acrylates, polyphenylethylenes and polyesters. Temporary adhesive adhesive according to claim 2, characterized in that the base resin has a weight average molecular weight of 5 × 10 ³ -5 × 10 ⁵ ; and that the base resin preferably has a melt index of 24 or greater. Temporary adhesive adhesive according to claim 1, characterized in that the solvent is one or at least two of propylene glycol monomethyl ether acetate, dimethylacetamide, propylene glycol monomethyl ether, ethyl lactate, limonene, mesitylene, cyclododecene and cyclopentanone. The temporary adhesive agent of claim 1, characterized in that it further comprises 0.05 to 0.07 part of a leveling agent and 0 to 0.15 part of an antioxidant based on 100 parts of the total amount of the temporary adhesive adhesive; wherein the leveling agent is preferably a fluorine-modified acrylate leveling agent; wherein the antioxidant is preferably a mixture of a polybasic hindered phenol antioxidant and a phosphite antioxidant.

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