JPH09262938A - Mold releasing film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use for a pressure sensitive adhesive tape during the production of a semiconductor device by forming a mold releasing layer containing a curing silicone resin containing fluorine as a main component on the surface of a polyester film which contains silicon dioxide particles of a specified particle size and a specified amount of a germanium element but does not contain other metal components. SOLUTION: A mold releasing layer containing a curing silicone resin containing fluorine as a main component is formed at least on one side of a polyester film which contains 10-200ppm of a germanium element and 0.01-2wt.% of silicon dioxide of 0.01-5μm average particle size but does not contain other metal components substantially. For this purpose, an esterification reaction is adopted for producing polyester, and a germanium compound which scarcely disturbs the normal functions of a semiconductor device is used as a catalyst. As the germanium compound, for example, the oxide, inorganic acid salt, organic acid salt, halide, and sulfide of germanium are named, but germanium dioxide is preferable in particular.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release film, and more particularly to a release film suitable for an adhesive tape used in manufacturing a semiconductor device.

[0002]

2. Description of the Related Art Semiconductors typified by silicon and germanium are used as diodes and transistors in various other applications such as oscillators, integrated circuits, and other devices that handle electrical signals, and are indispensable for current electronic technology. is there. For example, in an integrated circuit, a wafer is manufactured from a single crystal of silicon, a surface is oxidized, and then a photoresist process is performed.
It is manufactured through a background process and a dicing process.

In each of the above steps, an adhesive tape is used for the purpose of protecting and fixing the wafer. For example, in the background step, an adhesive tape is used for the purpose of protecting the circuit when polishing the side opposite to the circuit surface formed on the wafer. This adhesive tape is required to be removable and to have very little contamination on the wafer surface. Regarding the photoresist process, a method of removing the resist with an adhesive tape has been devised, as described in JP-A-6-267893. In this case as well, since the adhesive tape directly contacts the wafer, the amount of ionic impurities contained in the adhesive is required to be extremely small.

Polyester film is usually used as the base material of the pressure-sensitive adhesive tape used in each of the above-mentioned applications. Further, the polyester film is also frequently used as the base material of the release film in contact with the pressure-sensitive adhesive layer. ing. The polyester film used as the base material of the release film is required to have an extremely small amount of ionic impurities in the film.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is that it contains a small amount of ionic impurities and is therefore particularly suitable for an adhesive tape used in the manufacture of semiconductor devices. To provide a release film.

[0006]

That is, the gist of the present invention is to add 10 to 200 ppm of germanium element and 0.01 to 2 silicon dioxide particles having an average particle size of 0.001 to 5 μm.
The release film is characterized in that a release layer containing a fluorine-containing curable silicone resin as a main component is provided on at least one surface of a polyester film containing wt% and containing substantially no other metal component.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
In the present invention, the polyester refers to a polyester having an ethylene terephthalate unit content of 70 mol% or more,
The polyester film, which is the base material of the release film, is produced by biaxially stretching the above polyester by a conventional method.

The first feature of the present invention resides in a catalyst for obtaining a polyester used as a base material of a release film, as described below. Polyester is produced by a polymerization reaction via a transesterification reaction using a lower alkyl ester of terephthalic acid and ethylene glycol as main raw materials. Alternatively, it is produced by a polymerization reaction using terephthalic acid and ethylene glycol as main raw materials and passing through an esterification reaction. And in the case of either manufacturing method,
From an economical point of view, an antimony compound is usually used as a catalyst, and the amount thereof is about 200 to 400 ppm in terms of Sb element based on the polyester.

However, according to the findings of the present inventors, the release film based on the polyester film containing the antimony compound inhibits the normal function of the semiconductor device. That is, the antimony compounds and additives remaining in the polyester film migrate to the pressure-sensitive adhesive layer or release layer, and as a result, when the release film is rolled up, the back surface of the release layer causes rearrangement of the pressure-sensitive adhesive layer surface. As a result, the surface of the wafer is contaminated and the normal operation of the semiconductor device is hindered. Further, according to the findings of the present inventors, the presence of compounds such as Li, Ca, Mg, and Mn used as a transesterification catalyst is also not preferable.

Therefore, in the present invention, an esterification reaction is adopted in the production of polyester, and a germanium (Ge) compound, which has been found to have a significantly low degree of inhibition on the normal function of a semiconductor device, is used as a polymerization catalyst. .

Examples of the Ge compound used in the present invention include Ge oxides, inorganic acid salts, organic acid salts, halides and sulfides. Among them, germanium dioxide (or its derivative) is preferable. It is preferably used. The amount used is 10 to 200 ppm, preferably 20 to 150 pp, as the amount of Ge element remaining in the polyester.
m, more preferably 25 to 90 ppm. If this amount is less than 10 ppm, the polymerization reaction does not proceed smoothly,
If it exceeds 200 ppm, it is not suitable for use in the present invention.

The second feature of the present invention is that silicon dioxide is blended with polyester in consideration of the slipperiness of the film. The particle size of silicon dioxide is 0.001 to
It is necessary to select from the range of 5 μm, preferably 0.01 to 3 μm, and the blending amount with respect to polyester is
It is necessary to select from the range of 0.01 to 2% by weight, preferably 0.02 to 0.5% by weight. When the particle size or content of silicon dioxide is less than the above range, the slipperiness of the film is not improved, and when it exceeds the above range, it is unsuitable for use in the present invention.

As the silicon dioxide particles used in the present invention, synthetic silicon dioxide particles are preferable because they have a relatively uniform particle size and contain few ionic impurities. The synthetic silicon dioxide particles may be produced by either a wet method or a dry method, and the metal element other than Si contained in the particles is preferably 500 ppm or less.

The polyester film of the present invention must contain substantially no metal compound other than Ge and Si compounds. That is, in the present invention,
A transesterification reaction catalyst represented by an alkali metal compound or an alkaline earth metal compound, and an additive capable of causing ionic impurities (for example, calcium carbonate, barium carbonate, kaolin, talc, zeolite, etc.) are substantially not used. The total amount of metal compounds other than Ge and Si compounds is 30 ppm with respect to polyester as a metal element.
Or less, preferably 10 ppm or less, more preferably 5 p
pm or less.

In the present invention, a phosphorus (P) compound may be used in combination if necessary. The phosphorus compound generally has the effect of deactivating the metal compound and improving the thermal stability of the polyester. It may be convenient to allow the phosphorus compound to be present in the polyester as P element in an amount of about 5 to 200 ppm. However, this amount is also preferably as small as possible, and specifically, 5 to 50 ppm is preferable.

In the present invention, two or more kinds of polyesters may be used to achieve the polyester film satisfying the above requirements. For example, blending a polyester containing silicon dioxide particles and having a Ge element compound content of more than 200 ppm with a polyester containing no silicon dioxide particles and having a Ge element compound content of less than 200 ppm to form a film. Is also possible.

In the present invention, as a method for producing the polyester film, a conventionally known method can be adopted. For example, after melt-extruding the above polyester into a sheet at 270 to 320 ° C., it is cooled and solidified at 40 to 70 ° C. to form an amorphous sheet, and then biaxially stretched longitudinally and laterally sequentially or simultaneously. , A method such as heat treatment at 160 to 240 ° C. (for example, the method described in JP-B 30-5639) can be used. Usually, the stretching temperature is 8
0 to 140 ° C., and the draw ratio is selected within the range of 2.5 to 5 times in each of the length and width. In the present invention, the thickness of the polyester film is usually 25 to 10 from the viewpoint of workability.
It is selected from the range of 0 μm, preferably 30 to 75 μm.

The polyester film of the present invention is
The thickness unevenness calculated from the difference between the maximum value and the minimum value of the thickness is usually 2.5% or less, and the heat shrinkage ratio in the longitudinal direction when held at 100 ° C for 5 minutes is usually 0.8% or less. Is preferred.
The preferable range of the thickness unevenness is 2.0% or less, and the preferable range of the heat shrinkage ratio is 0.4% or less. In order to improve the flatness of the film, it is effective to apply an electrostatic cooling method during the production of the amorphous sheet and appropriately select the stretching ratio during film formation. For improvement,
The heat treatment temperature after stretching is slightly increased (for example, 220 to 245).
It is effective to set to (° C).

In the present invention, it is necessary to use a fluorine-containing curable silicone resin for the release layer. When non-curable silicone resin or silicone adhesive is used,
As described above, migration of silicone to the pressure-sensitive adhesive layer increases. Further, when a curable silicone resin containing no fluorine is used, peeling at the time of mold release becomes heavy, and in some cases there is a problem that the peeling cannot be performed.

The fluorine-containing curable silicone resin has a structure in which a fluorine atom is introduced into the main chain or side chain, and the excellent solvent resistance, water repellency, heat resistance, and weather resistance of fluorine are the coating film characteristics. Reflected. Examples of the fluorine-containing curable silicone resin include a copolymer (fluorosilicone resin) type of γ-trifluoropropylmethylsiloxane monomer and dimethylsiloxane monomer, a fluorine-based vinyl monomer and a silicone-based vinyl. There is a copolymer type of a monomer and a vinyl monomer (JP-A-61-228078).
In the above copolymer, by manipulating the copolymerization ratio of each monomer, it is determined whether the characteristics of silicone are strongly reflected or the characteristics of fluorine are strongly reflected.

In the present invention, as a method for providing a fluorine-containing curable silicone resin coating film on a polyester film, a conventionally known coating such as bar coating, reverse roll coating, gravure coating, rod coating, air doctor coating, doctor blade coating, etc. The engineering method can be adopted. As a coating solvent, considering Freon regulations,
It is preferable to use a general-purpose hydrocarbon solvent. Specific examples of the coating solvent include n-hexane, xylene, toluene, ethyl acetate and the like, as well as ether type and isooctane type (industrial gasoline type).

The release layer containing a fluorine-containing curable silicone resin as a main component may be provided on only one side of the polyester film or on both sides. When the release layer is provided on only one surface, an antistatic layer or the like can be provided on the opposite surface, if necessary. The thickness of the release layer is preferably 0.01 to 4 μm from the viewpoint of coatability. When the thickness of the release layer is less than 0.01 μm, it is difficult to obtain a uniform coating film due to lack of stability in view of coating property, and conversely, 4 μm.
When it exceeds, it is too thick and not preferable in practical use.

[0023]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to the following examples. In the examples and comparative examples, “parts” means “parts by weight” as solid content. The evaluation method used in the present invention is as follows.

(1) Peelability evaluation: The release layer of the sample film was coated with a silicone adhesive tape (“No.
903UL "), the peeled state when peeled in the direction of 180 ° was evaluated according to the following three grades shown in Table 1.

[0025]

[Table 1] Good ... Peelable. Δ: Peelable but heavy peeling. ×: Cannot be peeled off.

(2) Evaluation of coating film adhesion (lab-off test): The degree of coating film drop-off after rubbing the release layer after coating and drying five times with a finger is evaluated according to the following three levels. did.

[0027]

[Table 2] O ... Almost no coating film is removed. Δ: The coating film is whitish, but has not fallen off. X: The fall of the coating film can be confirmed.

(3) Evaluation of residual adhesive ratio: The residual adhesive force was measured according to the following method. That is, a silicone adhesive tape (Nitto Denko's "N
o. 903UL ") is pressed back and forth once with a 2 kg rubber roller, and heat-treated at 100 ° C for 1 hour. Then, the sample film is peeled off from the pressure-bonded sample, and the adhesive tape is
IS-C-2107 (Adhesion to stainless steel plate: 1
Measure the adhesive strength according to the method of 80 ° peeling method),
This is the residual adhesive strength. The measurement is performed under the conditions of a temperature of 20 ± 2 ° C. and a relative humidity of 65 ± 5%.

The basic adhesive strength was measured according to the following method.
That is, the same adhesive tape (No.
903 UL), a sample film is pressure-bonded to a stainless steel plate according to JIS-C-2107, and the measurement is performed in the same manner as in the case of the residual adhesive force, which is taken as the basic adhesive force. The measurement is performed under the conditions of a temperature of 20 ± 2 ° C. and a relative humidity of 65 ± 5%.

From the above values, the residual adhesion ratio is calculated according to the formula: residual adhesion ratio = (residual adhesion / basic adhesion) × 100.

(4) Evaluation method for substituting the amount of ionic impurities: The surface of a silicon substrate was oxidized by a conventional method, and electrodes were formed by a photoresist method to prepare a large number of Zener diodes. At this time, a release film obtained by using the germanium-based polymerization catalyst described above and using a film made of polyester containing silicon dioxide particles was used as a separator. Then, the adhesive tape was peeled off, the adhesive layer was overlaid on a silicon substrate having a resist, and a resist peeling step was performed.

The variation in Zener voltage between the elements in the substrate obtained as described above was measured. The voltage variation is expressed in% of the standard Zener voltage. The evaluation of substitution of the amount of ionic impurities was performed in two stages shown in Table 3 below. The base material used for the adhesive tape used this time also uses the above-mentioned polyester film containing a germanium-based polymerization catalyst and silicon dioxide particles.

[0033]

[Table 3] Low ...- Zener voltage variation is 2.0% or less. Many: The variation in Zener voltage exceeds 2.0%.

Example 1 86 parts of terephthalic acid and 70 parts of ethylene glycol were placed in a reactor and an esterification reaction was carried out at about 250 ° C. for 4 hours. Next, 0.012 parts of germanium dioxide, 0.1 part of silicon dioxide (wet method) having an average particle size of 1.5 μm, and 0.01 part of phosphoric acid (32 p as a P element relative to the polymer)
pm) was added, the temperature was gradually raised from 250 ° C. to 285 ° C., and the pressure was gradually reduced to 0.5 mmHg. Four
After a lapse of time, the polymerization reaction was stopped, and polyethylene terephthalate having an intrinsic viscosity of 0.65 was obtained. The amounts of Ge and P elements remaining in the obtained polyester are
It was 45 ppm and 25 ppm.

Next, after drying the above polyester,
It was extruded at 290 ° C. and cooled and solidified on a casting drum while applying an electrostatic applied cooling method to obtain an unstretched sheet.
Then, the unstretched sheet is stretched in the longitudinal (longitudinal) direction at 95 ° C. by 3.5 times, and in the transverse direction at 110 ° C. by 4.0 times, 235
A heat treatment was performed at 2 ° C. for 2 seconds to obtain biaxially stretched polyester film having thicknesses of 38 μm and 50 μm. The resulting film has a thickness variation of 1.6% and a longitudinal heat shrinkage of 0.2.
%Met.

The polyester film (38 μm) obtained by the above-mentioned production method was coated with the following release agent by a bar coating method so that the coating thickness after drying was 0.1 g / m ² to obtain a release film. Obtained. Table 4 shows the evaluation results of the release film.

The composition of the release agent is 10% fluorine-containing curable silicone resin ("X-70-1801" manufactured by Shin-Etsu Chemical Co., Ltd.).
0 parts, curing agent (“cat-PL-50” manufactured by Shin-Etsu Chemical Co., Ltd.
T ") 1 part and n-hexane 400 parts.

Example 2 In Example 1, the composition of the release agent was changed, and 100 parts of a fluorine-containing curable silicone resin (“Sirotex 3062” manufactured by Dow Corning Asia Co.) and a curing agent (Dow Corning "FSXK3020" manufactured by Asia Ltd.) 1
Parts, catalyst 1 part, n-hexane 200 parts, and acetic acid ethyl ester 200 parts were obtained in the same manner as in Example 1 to obtain a release film. Table 4 shows the evaluation results of the release film.

Comparative Example 1 In Example 1, antimony trioxide 0.0 was used instead of germanium dioxide as a polymerization catalyst for polyester production.
Release films were obtained in the same manner as in Example 1 and Example 1 except that 3 parts were used. In the polyester of this example, in addition to silicon dioxide particles, Sb element is 245 ppm and P element is 2
It was contained at 7 ppm. Table 4 shows the evaluation results of the release film.
Shown in

Comparative Example 2 In Example 1, 100 parts of the curable silicone resin (1) (“KS-723A” manufactured by Shin-Etsu Chemical Co., Ltd.) containing no fluorine was used, except that the composition of the release agent was changed.
25 parts of fluorine-free curable silicone resin (2) ("KS-723B" manufactured by Shin-Etsu Chemical Co., Ltd.), 5 parts of curing agent ("cat-PS-3" manufactured by Shin-Etsu Chemical Co., Ltd.), 700 parts of methyl ethyl ketone, 800 parts of toluene , N-heptane was prepared in the same manner as in Example 1 except that the release film was obtained. Table 4 shows the evaluation results of the release film.

Comparative Example 3 In Example 1, the composition of the release agent was changed, 100 parts of polyether-modified silicone oil (“KF-3501” manufactured by Shin-Etsu Chemical Co., Ltd.) as a non-reactive silicone resin, and an acrylic water dispersion. 20 parts, water 200 parts, ethanol 1000
A release film was obtained in the same manner as in Example 1 except that the parts were used. Table 4 shows the evaluation results of the release film.

[0042]

[Table 4] ─────────────────────────────────── Example Comparative Example 1 2 1 2 3 3 Film Thickness 38 (38) 38 38 38 38 38 Release layer thickness (μm) 0.1 0.1 0.1 0.1 0.1 Peelability 〇 〇 〇 △ × Residual adhesion rate (%) 90 90 90 85 65 Release layer adhesion 〇 〇 〇 〇 × Amount of ionic impurities Small Small Small Small Large ────────────────────────────────────

[0043]

The release film of the present invention is suitable as a release film for a pressure-sensitive adhesive tape substrate, which is used particularly in the production of semiconductor devices, because it uses a polyester film having extremely small ionic impurities as a base material.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 67/02 KJS C08L 67/02 KJS C09J 7/02 JHR C09J 7/02 JHR JKV JKV JKY JKY JLE JLE

Claims (2)

[Claims] 1. A germanium element in an amount of 10 to 200 ppm
And a fluorine-containing curable silicone resin as a main component on at least one side of a polyester film containing 0.01 to 2% by weight of silicon dioxide particles having an average particle size of 0.001 to 5 μm and substantially not containing other metal components. A release film, which is provided with a release layer. 2. The release film according to claim 1, which is for an adhesive tape substrate used in manufacturing a semiconductor device.