WO2016107146A1

WO2016107146A1 - Temporary bonding adhesive for processing thin wafer and preparation method thereof

Info

Publication number: WO2016107146A1
Application number: PCT/CN2015/084687
Authority: WO
Inventors: 孙蓉; 帅行天; 邓立波; 张国平; 郭慧子
Original assignee: 深圳先进技术研究院
Priority date: 2014-12-31
Filing date: 2015-07-21
Publication date: 2016-07-07
Also published as: DE212015000125U1; CN104559852B; CN104559852A; JP2017519852A; JP6148414B1

Abstract

Disclosed in the present invention are a temporary bonding adhesive for processing a thin wafer and a preparation method thereof. Per 100 total parts by weight of the temporary bonding adhesive, the temporary boding adhesive comprises 55 to 70 parts by weight of a solvent and 30 to 45 parts by weight of a base resin dissolved or dispersed in the solvent. The base resin is a high polymer or a high polymer blend having a thermal decomposition temperature above 320˚C and a melt index above 24. The temporary bonding adhesive advantageously has a high thermal stability and a high corrosion resistance; furthermore, bonding/de-bonding of the temporary bonding adhesive is efficient, thus allowing easy cleaning of the residual adhesive layer, and preparation of the temporary bonding adhesive is economical.

Description

Temporary bonding glue for thin wafer processing and preparation method thereof

Technical field

The invention relates to the technical field of adhesives, in particular to a temporary bonding adhesive for thin wafer processing and a preparation method thereof.

Background technique

In recent years, computers, communications, automotive electronics, and other consumer products have placed higher demands on microelectronic packaging, namely, smaller, thinner, more versatile, and lower cost. To meet the miniaturization needs of these products, the semiconductor industry needs to thin the device wafer to less than 100μm. Ultra-thin wafers are flexible and fragile, easy to warp and undulate, so the device wafer is usually bonded to a thicker carrier with a temporary bonding material, through the back thinning, forming a redistribution layer and After the internal interconnect is fabricated, external energy (light, electricity, heat, and external force) is input to disable the bonding layer, and then the device wafer is separated from the carrier. This process is a temporary bonding process of the wafer. Among them, the temporary bonding glue used to fix the thin wafer is the key to the success of the temporary bonding process.

Chinese Patent No. CN104130727A discloses a pressure-sensitive temporary bonding adhesive comprising 30-70 parts of a solvent, 30-50 parts of a base resin, and 5-30 parts of microcapsule particles, wherein the base resin is a cyclic olefin polymer particle, a solvent. Is cyclododecene, dicyclohexene, limonene, mesitylene, cyclopentanone, methylcyclohexane, methyl ethyl ketone, dipentene, cyclooctane, butyl cyclohexane, cycloheptane and cyclohexane a mixture of one or more of alkane, the microcapsule particle structure being composed of an inner core of a polymer compound and an outer layer of a continuous or outer phase of a natural or synthetic polymer compound, and further comprising a tackifier and a low molecular weight ring. One or a mixture of an olefin copolymer, a plasticizer, and an antioxidant. Chinese patent CN102203917A discloses a composition for temporary wafer bonding, which composition is composed of a free tackifier, a low molecular weight cyclic olefin copolymer, a plasticizer, an antioxidant, wherein the tackifier is selected from the group consisting of Polymyrene resin, R-poly mushroom resin, styrene modified mushroom resin, polymerized rosin resin, rosin resin, alicyclic hydrocarbon resin, C ₅ aliphatic hydrocarbon resin, hydrogenated hydrocarbon resin, low molecular weight cyclic olefin copolymer It has a weight average molecular weight of less than about 50,000 Daltons. In the above prior art, the temporary bonding adhesive still has a technical defect of low thermal stability and poor corrosion resistance.

Summary of the invention

In view of this, an aspect of the present invention provides a temporary bonding adhesive having high thermal stability and high corrosion resistance.

A temporary bonding adhesive for thin wafer processing, characterized in that the total mass of the temporary bonding adhesive is 100 parts, including 55 to 70 parts of a solvent, and 30 to 45 parts dissolved or dispersed in a solvent. A base resin which is a high polymer or a blended polymer having a thermal decomposition temperature of 320 ° C or higher.

In the above temporary bonding adhesive, the thermal decomposition temperature of the base resin is above 320 ° C to ensure that the bonding layer formed by the temporary bonding adhesive has good thermal stability. The base resin has a weight average molecular weight of from 5 × 10 ³ to 5 × 10 ⁵ and a melt index of 24 or more.

Specific examples of the high polymer are polyalkyl acrylates, polyphenylenes, and polyesters.

The high polymer is a polyalkyl acrylate which contains repeating units in the molecular structure.

a homopolymer or interpolymer, wherein R ₁ is a C _1-2 aliphatic hydrocarbon or an aromatic hydrocarbon, and R ₂ is a C _1-3 aliphatic hydrocarbon or an aromatic hydrocarbon. For example, polymethyl methacrylate. When the number of carbon atoms in R ₁ is 1, and the number of carbon atoms in R ₂ is 1, (ie, PMMA), the glass transition temperature T _g is 105 ° C; the number of carbon atoms in R ₁ is 2, and the number of carbon atoms in R ₂ is 1. (ie PEMA), the T _g is 65 ° C; the number of carbon atoms in R ₁ is 4, and the number of carbon atoms in R ₂ is 1 (ie PBMA), the T _g is 20 ° C, and its thermal decomposition temperature in air is higher. Low (220 ° C only). As the number of R ₁ carbon atoms increases, the flexibility of the polymer increases, the T _g becomes lower and lower, the viscous flow temperature (T _f ) also decreases, and the T _{f is} too small, which affects the use temperature of the temporary bonding adhesive. The number of carbon atoms of R ₂ is preferably from 1 to 3, and may be an aromatic hydrocarbon. It is worth noting that the number of carbon atoms in R ₂ may not be less than 1, and the methyl acrylate obtained when the number of carbon atoms of R ₂ is zero Tg is too low (only 6 ° C).

Polyphenylene, which contains repeating units in the molecular structure

a homopolymer or interpolymer, wherein R ₁ and R _{2 are} preferably C _1-3 aliphatic hydrocarbons or aromatic hydrocarbons. If both R ₁ and R ₂ are aliphatic hydrocarbon groups, the olefin polymer formed on the one hand has a low T _g due to the absence of a side chain group in its molecular structure, and on the other hand it is easily crystallized (for example, PE, PP, PMP have High crystallinity), which may affect the performance of the base resin as an adhesive material; if the aliphatic hydrocarbon chain is too long, it will increase the flexibility of the polymer and lower its T _g , which will affect the use temperature of the bonding adhesive. .

Polyester, which contains repeating units in the molecular structure

a homopolymer or interpolymer, wherein R is cyclohexane, phenyl or hexyloxy,

which is

Here, as the polyester, a physical blend of three polyesters of A, B and C can be used. The mass content ranges of A, B, and C are 10 to 60%, 10 to 80%, and 0 to 50%, respectively, and the molecular weight ranges of A, B, and C are 8,000 to 30,000, 5,000 to 50,000, and 5,000 to 100,000, respectively.

It should be noted that, for example, the blended polymer may be one or more polyalkyl acrylates, and may be one or more polyphenylenes or one or more polyesters. Also can be one A mixture of a polyalkyl acrylate and a polyphenylene, or a mixture of a polyalkyl acrylate and a polyester, and the like. As an embodiment, for example, a polyacrylate having a molecular weight of 5,000 to 30,000,000 and a poly-α-methylstyrene having a molecular weight of 3,000 to 20,000 may be used, and the mass ratio of the two is 2:1 to 20:1.

The boiling point of the solvent is preferably above 80 ° C and the polarity is similar to 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, decene, mesitylene, cyclododecene, and cyclopentanone. .

Further, the total mass of the temporary bonding adhesive is 100 parts, and further includes 0.05 to 0.07 parts of a leveling agent and 0 to 0.15 parts of an antioxidant.

Here, the leveling agent is preferably an acrylate-based leveling agent modified with fluorine. The antioxidant is preferably composed of a multi-hindered phenolic antioxidant as a main antioxidant and a phosphite antioxidant as an auxiliary antioxidant, and the combination of the two helps to improve the heat of the bonding adhesive. stability.

In the above temporary bonding glue, a preferred formulation comprises 20-30 parts of PMMA, 10-15 parts of poly-α-methylstyrene, 55-70 parts of solvent and 0.05-0.07 parts of FC-4430 leveling. More preferably, the raw material comprises 24 parts of PMMA, 12 parts of poly-α-methylstyrene, 64.95 parts of DMAc and 0.05 parts of a type IV-4430 leveling agent.

According to still another aspect of the present invention, a method for preparing a temporary bonding adhesive is provided, and a temporary bonding adhesive having high thermal stability and high corrosion resistance can be obtained by the preparation method.

A preparation method of the above temporary bonding glue, wherein 30 to 45 parts of the base resin, 55 to 70 parts of the solvent and 0.05 to 0.07 parts of the leveling agent are stirred and mixed under heating conditions, and then cooled and degassed. , get temporary bonding glue.

In the above preparation method, the heating method is a water bath at 60 to 70 ° C; the stirring method is mechanical stirring at a speed of 100 to 1000 rpm; and the degassing treatment is vacuum degassing by a vacuum deaerator.

In still another aspect of the present invention, there is provided a method of bonding a thin wafer using the temporary bonding adhesive having good thermal stability and corrosion resistance as described above.

A method for bonding a thin wafer by using the above temporary bonding glue, specifically: after the temporary bonding glue is spin-coated on the surface of the carrier wafer, and the solvent is dried, the device wafer is covered on the surface Then, the temporary bonding glue is heated to melt and cool to form a bonding layer.

In the above bonding method, the manner of heating the temporary bonding glue may be a baking method. The other surface of the wafer that is not coated with the bonding adhesive can be directly transferred by baking. During the heating of the bonding glue, the solvent in the bonding adhesive first volatilizes, and then with the continuation of the heating, the base resin slowly melts at about 200 ° C, and is cooled and solidified to form a bonding layer, thus carrying the wafer and the device wafer. The surface is keyed. After curing to form the bonding layer, the DMAc is used to clean the remaining adhesive layer on the periphery of the device wafer, and similarly, DMAc can be used as a cleaning agent to dissolve the bonding layer during the debonding of the device wafer.

The temporary bonding adhesive of the present invention comprises 55 to 70 parts of a solvent and 30 to 45 parts of a base resin dissolved or dispersed in a solvent, the base resin is a thermal decomposition temperature, based on 100 parts by mass of the total mass of the temporary bonding glue. a polymer having a melt index of 24 or more or a blend of high polymers at 320 ° C or higher, whereby the temporary bonding adhesive has the advantages of high thermal stability and high corrosion resistance, and has high bonding/debonding efficiency and residual viscosity. The layer is easy to clean and the preparation cost is economical.

DRAWINGS

1 is a graph showing a thermogravimetric change of a dry film of a coating of a temporary bonding adhesive according to Embodiment 1 of the present invention;

2 is a graph showing the thermogravimetric change of the dry film of the coating of the temporary bonding adhesive of Example 2 of the present invention;

Figure 3 is a graph showing the viscosity and temperature of a solvent-free temporary bonding adhesive of Example 2 of the present invention;

Figure 4 is a graph showing the thickness distribution of the temporary bonding adhesive coating dry film of Example 2 of the present invention;

Figure 5 is an ultrasonic scanning micrograph of a temporary bonding glue bonded wafer of Example 2 of the present invention.

detailed description

The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

Example 1

2.4 g of polymethyl methacrylate, 1.2 g of poly-α-methylstyrene, 5 mg of FC-4430 type leveling agent, and 6.395 g of DMAc were placed in a hot-dissolving vessel equipped with a stirring apparatus and a water bath heating system. The temperature of the water bath is controlled at 60-70 ° C, and the mixer is started, and the rotation speed is adjusted to 100-1000 rpm. When the raw materials are fully stirred and uniformly taken out, they are naturally cooled and cooled, placed in a vacuum degassing machine, deaerated under vacuum, and finally sealed and stored.

Example 2

In this example, the raw materials specifically include: 4 g of homemade polyester, 5 mg of 4430 leveling agent, and 5.995 g of solvent PGMEA; and stirred at room temperature for 1 hour.

Except for the above conditions, the same applies to Example 1.

Example 3

In this example, the raw material specifically comprises: 2.0 g of polymethyl methacrylate, 1.0 g of poly-α-methylstyrene, 5 mg of FC-4430 type leveling agent, and 5.5 g of DMAc; example 1.

Example 4

In this example, the raw material specifically includes: 3.0 g of polymethyl methacrylate, poly 1.5 g of α-methyl styrene, 7 mg of FC-4430 type leveling agent, and 7.0 g of DMAc; otherwise, the same applies to the examples. 1.

The test results of the corrosion resistance of Example 1 and Example 2 are as follows in Table 1 and Table 2 below (in view of the specific test methods are well known to those skilled in the art, the method will not be described in detail herein):

Table 1

Table 2

As shown in Fig. 1 and Fig. 2, the thermogravimetric change curves of Examples 1 and 2, respectively, can be seen from the figure, the phenomenon of decomposed weight loss occurs in the dry film from 300 ° C, and the weight loss rate at 450 ° C is 80%. That is, most of the decomposition occurs, and thus it can be seen that the temporary bonding adhesive of the present invention has good thermal stability.

As shown in FIG. 3, it is a viscosity graph of the temporary bonding adhesive of Example 1. As can be seen from the figure, the overall change in viscosity with temperature is mild, thus indicating that the temporary bonding adhesive of the present invention has better viscosity stability.

As shown in FIG. 4, it is a thickness distribution diagram of the dry film of the temporary bonding adhesive coating of Example 2 of the present invention. It can be seen from the figure that the thickness of the temporary bonding adhesive coating is relatively uniform, thereby indicating that the average thickness of the bonding layer is 22.7 μm and the standard deviation is 0.5, indicating that the thickness of the bonding layer is appropriate and the bonding layer is flat. The better coating effect, the process requirements of the coating are not critical.

As shown in FIG. 5, an ultrasonic scanning micrograph after bonding a wafer using the temporary bonding glue of Example 2 of the present invention. As can be seen from the figure, it can be seen that the bonding layer between the two bonded silicon wafers has no voids (no white spots) and is evenly distributed.

Although the numerical ranges of the various process parameters involved in the present invention are not fully exemplified in the above embodiments, those skilled in the art can fully imagine that the present invention can be implemented by any numerical value falling within the above numerical range. It is of course also intended to include any combination of specific values within a range of values. Herein, for the sake of consideration, embodiments that give specific values within a certain numerical range or values are omitted, and should not be considered as a sufficient embodiment for the formulation and process scope claimed in the technical solution of the present invention. Support for understanding.

The Applicant declares that the present invention illustrates the detailed process equipment and process flow of the present invention by the above embodiments, but the present invention is not limited to the above detailed process equipment and process flow, that is, does not mean that the present invention must rely on the above detailed process equipment and The process can only be implemented. It should be apparent to those skilled in the art that any modifications of the present invention, equivalent substitution of the various materials of the products of the present invention, addition of auxiliary components, selection of specific means, and the like, are all within the scope of the present invention.

Claims

A temporary bonding adhesive for thin wafer processing, characterized in that the total mass of the temporary bonding adhesive is 100 parts, and comprises 55 to 70 parts of a solvent and 30 to 45 dissolved or dispersed in a solvent. The base resin is a high polymer or a blended polymer having a thermal decomposition temperature of 320 ° C or higher.
The temporary bonding adhesive according to claim 1, wherein the high polymer is a polyalkyl acrylate having a repeating unit in a molecular structure
a homopolymer or interpolymer, wherein R 1 is a C 1-2 aliphatic or aromatic hydrocarbon, and R 2 is a C 1-3 aliphatic or aromatic hydrocarbon;

Or polyphenylene, which contains repeating units in the molecular structure
a homopolymer or interpolymer, wherein R 1 , R 2 are C 1-3 aliphatic or aromatic hydrocarbons;

Or a polyester, which contains repeating units in the molecular structure
a homopolymer or interpolymer, wherein R is cyclohexane, phenyl or hexyloxy.
The temporary bonding adhesive according to claim 2, wherein the blended high polymer is at least two of the polyalkyl acrylates, polyphenylenes, and polyesters.
The temporary bonding adhesive according to claim 2, wherein the base resin has a weight average molecular weight of 5 × 10 3 to 5 × 10 5 ;

Preferably, the base resin has a melt index of 24 or more.
The temporary bonding adhesive according to claim 1, wherein the solvent is propylene glycol monomethyl ether acetate, dimethylacetamide, propylene glycol monomethyl ether, ethyl lactate, decene, mesitylene, One or at least two of cyclododecene and cyclopentanone.
The temporary bonding adhesive according to claim 1, wherein the total of the temporary bonding glue is based The mass is 100 parts, and further comprises 0.05 to 0.07 parts of a leveling agent and 0 to 0.15 parts of an antioxidant;

Preferably, the leveling agent is a fluorine-modified acrylate leveling agent;

Preferably, the antioxidant is a mixture of a multi-hindered phenolic antioxidant and a phosphite antioxidant.
A method for preparing a temporary bonding adhesive according to any one of claims 1 to 6, wherein 30 to 45 parts of the base resin and 55 to 30 parts by total mass of the temporary bonding adhesive are 100 parts by weight. 70 parts of the solvent and 0.05 to 0.07 parts of the leveling agent and 0 to 0.15 parts of the antioxidant are stirred and mixed under heating, and then cooled and degassed to obtain a temporary bonding gel.
The preparation method according to claim 7, wherein the heating is performed at 60 to 70 ° C in a water bath;

Preferably, the stirring is performed by mechanical stirring at a speed of 100 to 1000 rpm;

Preferably, the degassing treatment is performed by vacuum degassing using a vacuum degasser.
A method of bonding a thin wafer using the temporary bonding adhesive according to any one of claims 1 to 6, characterized in that the first substrate and the first substrate bonded by the temporary bonding adhesive are provided a laminate of two substrates; and heating the temporary bonding adhesive to cure to form a bonding layer.
The method according to claim 9, wherein said step of heating the temporary bonding adhesive to form a bonding layer further comprises the step of cleaning the remaining adhesive layer on the periphery of the device wafer with DMAc.