JPH1161079A - Temporary adhesive for precision processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive which is soluble in an aq. alkali soln. and hence is excellent in peelabiliy after temporary adhesion work by incorporating a novolak epoxy resin contg. an acid anhydride added thereto, a shellac resin and a plasticizer, each in a specified amt., into the same. SOLUTION: This adhesive is soluble in an aq. alkali soln. and contains 100 pts.wt. resin mixture of a novolak epoxy resin (A) contg. an acid anhydride added thereto and a shellac resin (B) in a wt. ratio of A/B of (100/3)-(100/20) and 3-35 pts.wt. plasticizer. Ingredient A is obtd. by adding an acid anhydride (e.g. hexahydrophthalic anhydride) to a reaction product of a phenol novolak epoxy resin or the like with a mono- or polyhydric phenol and pref. has a softening point of 60-120 deg.C, an acid value of 80-200 mgKOH/g and a metal ion content of 50 ppb or lower. Ingredient B pref. has an acid value of 70 mgKOH/g or higher. Ingredient C is selected from among toluenesulfonic acid ethylamide, phthalic ester compds., oxy-acid ester compds., etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temporary processing adhesive used for temporary processing of silicon, gallium arsenide, glass materials, magnetic materials, metal materials, quartz, optical lenses, and the like. The present invention relates to an adhesive useful for temporary attachment in various processes such as cutting, drilling, polishing, and temporary attachment between a wafer and a surface plate.

[0002]

2. Description of the Related Art Conventionally, as an adhesive for the above-mentioned applications, petroleum resin, paraffin wax, modified rosin, for example, polymerized rosin, maleated rosin, rosin ester, shellac resin, carnauba, beeswax, Animals and plants, such as montan wax, and minerals have been used.

[0003]

However, these modified adhesives based on natural raw materials contain a large amount of impurities of metal ions. The remaining ions have led to a decrease in the device function of the semiconductor. As a countermeasure, a method of removing metal ions by an ion exchange method or a chelating treatment method is known. However, it is difficult to remove metal ions such as Al and Sn, and it has not been possible to respond to a requirement of several tens of ppb order. In addition, many conventional adhesives require the use of an organic solvent to remove the adhesive, and in this case, there has been a major problem in environmental hygiene such as air pollution and destruction of the natural environment. .

A first object of the present invention is to provide a temporary bonding for precision processing which is excellent in surface smoothness, adhesiveness, detergency, etc., has a very low content of metal ions and has little influence on semiconductor devices. To provide an agent.

[0005] A second object of the present invention is to provide a temporary processing adhesive for precision processing which has excellent releasability after the temporary bonding operation.

A third object of the present invention is to provide a temporary processing adhesive for precision processing which does not require an organic solvent for removal and can solve environmental health problems.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a novolak-type epoxy resin and a shellac-based resin to which an acid anhydride has been added in a temporary bonding adhesive for precision processing. Is a main component and a predetermined amount of a plasticizer is blended in the temporary adhesive, the amount of residual metal ions can be easily maintained at a level that does not affect the function of the semiconductor device, and the releasability after the temporary attaching operation is excellent. The present invention has been found to exhibit excellent performance as a temporary adhesive, and to be safe in terms of environmental hygiene, and completed the present invention.

[0008] The first temporary processing adhesive for precision processing of the present invention is:
The resin mixture 100 is mainly composed of a novolak type epoxy resin to which an acid anhydride is added and a shellac resin.
A plasticizer is contained in a range of 3 parts by weight to 35 parts by weight with respect to parts by weight, and is soluble in an aqueous alkali solution.

It is characterized in that the shellac resin is contained in the range of 3 to 20 parts by weight based on 100 parts by weight of the novolak type epoxy resin to which the acid anhydride is added.

The plasticizer is one or a mixture of two or more selected from the group consisting of toluenesulfonic acid ethylamide, phthalic ester compounds, oxyester compounds and aliphatic dibasic ester compounds. There is a feature.

The temporary processing adhesive for precision processing described above is a temporary bonding adhesive for wafer precision processing and has a metal ion content of 50 p.
pb or less.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a description will be given mainly of a case where a temporary bonding adhesive for precision processing of the present invention is used for wafer precision processing. A novolak type epoxy resin to which an acid anhydride as a main component of the adhesive is added (hereinafter referred to as an epoxy resin) is composed of a novolak type epoxy resin such as a phenol novolak epoxy resin and a monovalent or polyvalent phenol or alcohol. Is obtained by further adding an acid anhydride such as hexahydrophthalic anhydride to the reaction product of the above, and has a softening point of 60 ° C. to 120 ° C. and an acid value of 80 mg KOH.
/ G to 200 mgKOH / g. Softening point is 1
If the temperature exceeds 20 ° C., thermal distortion of the wafer occurs during bonding, which is not preferable. If the acid value is lower than 80 mgKOH / g, alkali solubility decreases.

[0013] The content of metal ions in the epoxy resin is preferably 50 ppb or less. Also, unlike natural resins, the content of metal ions can be easily reduced. , The control of the metal ion content becomes easy. Examples of such a resin include AX311M (solid concentration 70%, acid value 120 mgKOH / g) manufactured by Toto Kasei Co., Ltd.

The shellac resin is added to the above-mentioned epoxy resin for the purpose of lowering the melting point, improving the razor peeling property, improving the alkali cleaning property, improving the smoothness, improving the solvent release (drying property), and the like. In any case, the acid value is preferably 70 mgKOH / g or more. 70mg
If it is less than KOH / g, the alkali solubility decreases. The content of metal ions in the shellac resin is usually 2
Since it is of the order of × 10 ⁴ ppb, the metal removal treatment is carried out by a usual method, and it is preferable to set the order to 100 ppb or less, preferably 50 ppb or less.

Examples of the shellac resin include natural shellac resin and synthetic shellac resin. Commercially available products include "trade name, shellac GS" manufactured by Gifu Cyerac Co., Ltd. and "trade name, shellac HK" manufactured by Koyo Chemical Co., Ltd. 65
８０80 mgKOH / g.

The shellac resin is used in an amount of 3 to 20 parts by weight, preferably 5 to 15 parts by weight, based on 100 parts by weight of the epoxy resin. If the amount is less than 3 parts by weight, the melting point decreases and the razor peels off. There is no effect such as improvement of the property, improvement of alkali cleaning property, improvement of smoothness, improvement of solvent separation (drying property), and more than 20 parts by weight increases the concentration of metal ions in the adhesive, Further, it is not preferable because the coating smoothness and the alkali cleaning property are reduced as an adhesive.

Examples of the plasticizer include one or a mixture of two or more selected from the group consisting of toluenesulfonic acid ethylamide, phthalic acid ester compounds, oxyacid ester compounds and aliphatic dibasic acid ester compounds. And preferred is toluenesulfonic acid ethylamide. The plasticizer may be contained in an amount of 3 to 35 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the mixed resin of the epoxy resin and the shellac resin. If it is less than 3 parts by weight, the softening point of the adhesive is too high,
Also, the coating smoothness is poor, and if it exceeds 35 parts by weight, the releasability after adhesion processing is deteriorated.

A rosin-based resin may be added as required in addition to the shellac resin. Rosin resin, like shellac resin, is similar to epoxy resin in lowering melting point, improving razor releasability, improving smoothness, and removing solvent (drying).
For example, rosin, rosin ester, partially or hydrogenated rosin, polymerized rosin, or modified rosin of these rosin resins with a dibasic acid such as maleic acid, or an ester derivative thereof And the like, and it is advisable to add it in an amount of 0 to 200 parts by weight, preferably 0 to 100 parts by weight, based on 100 parts by weight of the shellac resin. Since the content of metal ions in the rosin-based resin is usually on the order of 2,000 ppb, it is preferable to perform a metal removal treatment by a usual method, and to set the content on the order of several hundred ppb, preferably on the order of 30 ppb.

The components such as epoxy resin, shellac resin, and plasticizer are used as a temporary processing adhesive according to the present invention as a solution having a solid content of 20% to 50% in a solvent such as isopropyl alcohol or toluene. .

The temporary processing adhesive for precision processing of the present invention is applied on a wafer or a surface plate by a spin coater method, a spray method or the like, and after the solvent is removed, it is heat-pressed or the solvent is removed. The solid adhesive is melt-coated on the wafer or the surface plate, and then heated and pressed to securely fix the wafer on the surface plate. The wafer fixed in this way is subjected to polishing with an alkaline polishing liquid, and after the processing, the wafer is peeled off from the surface plate using a screver, a knife or the like.

The adhesive is required to bond and fix the wafer to the surface plate, to withstand the temperature rise of 40 ° C. to 50 ° C. and the alkali polishing solution during polishing, to reach mirror polishing, and to perform polishing. Later, for example, it is required that the blade of a razor be inserted into the bonding surface of the wafer and be peeled off at once, but in order to achieve both, the bonding strength is 25 kg.
/ Cm ^{2 to} about 35 kg / cm ² . The adhesive adhering to the peeled wafer is removed by performing primary cleaning with an alkaline cleaning agent and then performing a final rinse with pure water.

As the alkaline cleaning agent, an aqueous solution of an organic amine such as tetramethylammonium oxide, alkanolamine, amino alcohol, or water-soluble amine, an inorganic alkali, or a salt thereof may be used.
It is preferable to avoid mixing metal ions.

Further, the temporary bonding adhesive for precision processing of the present invention is
When used for cutting or polishing a crystal oscillator, a ferrite material, a metal material, a glass material, or the like, it is preferable to use a solid state and use as a hot melt type.

[0024]

Next, the present invention will be described in detail with reference to examples and comparative examples.

Example 1 (1) Novolak type epoxy resin solution to which hexahydrophthalic anhydride was added (AX311 manufactured by Toto Kasei Co., Ltd.)
M, an acid value of 120 mg KOH / g, a solid content of 70% by weight, and a solvent of 30%) were diluted with a solvent {isopropyl alcohol / toluene (weight ratio) = 2/1} to obtain a solution containing 300 parts by weight of a solid content of 36% by weight. , (2) Shellac resin {manufactured by Koyo Chemical Co., Ltd., acid value 65-85 mgKOH / g} was dissolved in a solvent {normal propyl alcohol / toluene (weight ratio) =
Solution 100 diluted by 3/7% to a solid content of 38% by weight
Parts by weight of toluene sulfonic acid ethylamide (Fujiamide Chemical Co., Ltd., Topsizer No.
3), 21 parts by weight of a mixed solvent {isopropyl alcohol / toluene (weight ratio) = 2/1} is added, and a temporary bonding adhesive for precision processing of a 40% by weight solid content solution (metal Content of 50 ppb or less).

The content of metal ions in the epoxy resin is 8 ppb for sodium ions, 0 ppb for aluminum ions, 2 ppb for zinc ions, and 16 ppb for iron ions.
ppb, nickel ion 1ppb, copper ion 2ppb,
Chromium ion is 2 ppb. Moreover, the above-mentioned shellac resin used was one subjected to a metal removal treatment by a cation ion exchange method.

(Comparative Example 1) A novolak-type epoxy resin solution (AX311M manufactured by Toto Kasei Co., Ltd., acid value 120 mgKOH / g, solid content 70% by weight, solvent 30%) to which hexahydrophthalic anhydride was added was mixed with a solvent isopropyl. The mixture was diluted with alcohol / toluene (weight ratio) = 2/1% to obtain a solution having a solid content of 40% by weight, which was used as an adhesive.

Comparative Example 2 An adhesive was prepared by changing the addition amount of the plasticizer in Example 1 to 40 parts by weight with respect to 100 parts by weight of the epoxy resin, and adjusting the total solid content to 40% by weight.

(Evaluation of Coating Smoothness) The liquid adhesive obtained in Example 1 and Comparative Examples 1 and 2 was applied to a glass wafer under the following conditions, and then used at 80 ° C. × 5 minutes using an electric oven. Heat and dry.

Coating conditions Apparatus: Mikasa spin coater 1H360 type Conditions: Initial rotation 1000 rpm / 2 sec to full rotation 3
000 rpm / 10 sec Coating thickness: 4 ± 0.5 μm After drying, the flatness of the coating surface was measured using a stylus-type surface roughness meter {Surfcom 574A, manufactured by Tokyo Seimitsu Co., Ltd.} to determine coating smoothness.

(Evaluation of Adhesive Strength) The liquid adhesive obtained in Example 1 and Comparative Examples 1 and 2 was applied to a stainless steel plate under the same application conditions as described above, and then heated and dried in the same manner. 120 ℃, 0.1k
The laminate was bonded under a heat / pressure condition of g / cm ² . The tensile shear strength of the bonded product was measured with a strograph (R-1 manufactured by Toyo Seiki Co., Ltd.).
The adhesive force (kg / cm ² ) was measured.

(Evaluation of Detergency) The adhesive adhered to the stainless steel plate peeled off in the above evaluation of the adhesive strength was washed with a 4% ammonium carbonate aqueous solution using a washing apparatus (Olympus Corporation).
30 ° C, 10 min. The cleaning property was evaluated.

(Evaluation of Softening Point) Example 1 and Comparative Example 1
The solvent was volatilized with a vacuum drier set at 80 ° C. for the liquid adhesive obtained in the above to obtain a solid adhesive, and the softening point (° C.) was determined by the ring and ball method.

Regarding the evaluation of coating smoothness and detergency, VG indicates a very good result, G indicates a good result, F indicates a normal result, and P indicates a poor result.

The results are shown in Table 1.

[0036]

[Table 1]

From Table 1, it can be seen that the temporary tack adhesive for precision processing of the present invention is superior in coating smoothness and adhesive strength as compared with Comparative Example 1 (without adding a plasticizer). In addition, it can be seen that Comparative Example 2 (containing 40 parts by weight of the plasticizer with respect to 100 parts by weight of the resin) has reduced adhesive strength.

Example 2 In place of the plasticizer used in Example 1, a mixture of toluene sulfonic acid ethyl amide (Topsizer No. 3 manufactured by Fujiamide Chemical Co., Ltd.): Oleic acid (weight ratio) = 2: 1 was used. Except for using, a temporary adhesive for precision processing was prepared in the same manner as in Example 1.

(Examples 3 to 5) The amount of the plasticizer added in Example 1 was changed to 5 with respect to 100 parts by weight of the epoxy resin.
The total solid concentration was adjusted to 40% by weight instead of 10 parts by weight (Example 3), 10 parts by weight (Example 4), and 25 parts by weight (Example 5) to prepare a temporary processing adhesive for precision processing. .

(Embodiments 6 to 9) The above embodiments 2 to 9
With respect to the liquid adhesive obtained in Example 5, the solvent was volatilized by a vacuum dryer set at 80 ° C., and the solid adhesive (Example 6)
To 9) were obtained.

(Comparative Examples 3 and 4) The liquid adhesives obtained in Comparative Examples 1 and 2 were volatilized by a vacuum dryer set at 80 ° C. to obtain solid adhesives (Comparative Examples 3 and 4). .

(Evaluation of Coating Smoothness) After the solid adhesives obtained in Examples 6 to 9 and Comparative Examples 3 and 4 were melted at 130 ° C., glass was placed on a hot plate set at 130 ° C. under the following conditions. The wafer was heated, coated with a spin coater, and cooled.

Coating conditions Apparatus: Mikasa spin coater 1H360 type Conditions: Initial rotation 1000 rpm / 2 sec to full rotation 3
500 rpm / 5 sec Coating thickness: 4 ± 0.5 μm The flatness of the coating surface was measured using a stylus type surface roughness meter (Surfcom 574A, manufactured by Tokyo Seimitsu Co., Ltd.) to determine the coating smoothness.

(Evaluation of Adhesive Strength) The solid adhesives obtained in Examples 6 to 9 and Comparative Examples 3 and 4 were melted at 120 ° C., and then applied to a stainless steel plate under the same application conditions as above. Another stainless steel plate was combined with the coated surface, and the stainless steel plates were bonded together at 120 ° C. under a heat and pressure condition of 0.1 kg / cm ² .
The tensile shear strength of the bonded product was measured using a strograph (R-1 manufactured by Toyo Seiki Co., Ltd.), and the adhesive force (kg / kg) was measured.
cm ² ).

(Evaluation of Detergency) The adhesive adhered to the stainless steel plate peeled off in the above evaluation of the adhesive strength was washed with a 4% ammonium carbonate aqueous solution using a washing apparatus (Olympus Corporation).
30 ° C, 10 min. The cleaning property was evaluated under the following conditions.

The evaluation method of the coating smoothness and the cleaning property is the same as the evaluation method of Example 1. Table 2 shows the results
Shown in

[0047]

[Table 2]

From Table 2, it can be seen that the temporary tacking adhesive for precision processing of the present invention improves the adhesive strength as a solid adhesive by adding a plasticizer. It can be seen that Example 4 (containing 40 parts by weight of the plasticizer with respect to 100 parts by weight of the resin) has a reduced adhesive strength.

Example 10 (1) Novolak type epoxy resin solution to which hexahydrophthalic anhydride was added (AX311 manufactured by Toto Kasei Co., Ltd.)
M, an acid value of 120 mg KOH / g, a solid content of 70% by weight, and a solvent of 30%) were diluted with a solvent {isopropyl alcohol / toluene (weight ratio) = 2/1} to obtain a solution containing 300 parts by weight of a solid content of 36% by weight. , (2) shellac resin {manufactured by Koyo Chemical Co., Ltd., acid value 65-80 mgKOH / g}, solvent {normal propyl alcohol / toluene (weight ratio) =
50 parts by weight of a solution diluted with 3/7% to a solid content of 38% by weight, and (3) a modified rosin ester (Arakawa Chemical Co., Ltd.)
And an acid value of 67 mg KOH / g) were diluted with a solvent {normal propyl alcohol / toluene (weight ratio) = 3/7} to obtain a solid content of 38% by weight. (Fujiamide Chemical Co., Ltd., Top Sider No. 3) 14
Parts by weight were mixed to prepare a temporary processing adhesive (metal content: 46 ppb) for a precision processing of a solution having a solid content of 40% by weight.

The content of metal ions in the above-mentioned epoxy resin and shellac resin is the same as in Example 1.

Example 11 The liquid adhesive obtained in Example 10 was volatilized with a vacuum dryer set at 80 ° C. to obtain a solid adhesive.

The liquid adhesive obtained in Example 10 was obtained by the same method as in Example 1 described above, and the solid adhesive obtained in Example 11 was obtained by the same method as in Examples 2 to 5 described above. evaluated. The results are shown in Table 3 below.

[0053]

[Table 3]

From Table 3, it was found that the addition of the shellac resin and the rosin-based resin to the epoxy resin resulted in excellent coating smoothness and cleaning properties, and also excellent drying properties and peelability.

[0055]

The temporary adhesive for precision processing of the present invention comprises epoxy resin and shellac resin as main components and a predetermined amount of a plasticizer. Adhesive with excellent properties, detergency and softening point. Further, by reducing the content of metal ions as impurities, the function of the semiconductor device can be prevented from being affected. Furthermore, since an alkaline aqueous solution can be easily used for the removal, an organic solvent is not required, and an environmentally safe adhesive free from poisoning and fire can be obtained.

Claims (4)

[Claims] 1. A novolak-type epoxy resin to which an acid anhydride has been added, and a shellac-based resin as main components, and a plasticizer in a range of 3 parts by weight to 35 parts by weight based on 100 parts by weight of the resin mixture. Temporary adhesive for precision processing characterized by being soluble in an aqueous alkaline solution. 2. The precision processing according to claim 1, wherein the shellac resin is contained in the range of 3 to 20 parts by weight based on 100 parts by weight of the novolak type epoxy resin to which the acid anhydride is added. For temporary adhesive. 3. The plasticizer is one or a mixture of two or more selected from the group consisting of toluenesulfonic acid ethylamide, phthalic acid ester compounds, oxyacid ester compounds, and aliphatic dibasic acid ester compounds. The temporary adhesive for precision processing according to claim 1 or 2, wherein the adhesive is used. 4. The temporary processing adhesive for precision processing is a temporary bonding adhesive for wafer precision processing, and has a metal ion content of 50 ppb.
The temporary processing adhesive according to any one of claims 1 to 3, wherein: