JP5603453B1 - Adhesive tape for semiconductor wafer protection - Google Patents

Abstract

An adhesive tape for protecting a semiconductor wafer having heat resistance and heat shrinkage resistance, which is not fused or excessively shrunk to a chuck table even when exposed to high heat in a gas etching process or a plasma dicing process. provide.
A base film 3 and an adhesive layer 5 formed on one side of the base film 3 are provided. The base film 3 includes a cast film layer 7 containing a cured resin. The adhesive tape 1 for protecting a semiconductor wafer is used, which is provided in the outermost layer on the side where it is not formed, and the tack force of the cast film layer 7 is 100 kPa or less at 200 ° C. Moreover, you may use the adhesive tape 1a for semiconductor wafer protection which a base film consists only of the cast film layer 7. FIG.
[Selection] Figure 1

Description

  The present invention relates to an adhesive tape for protecting a semiconductor wafer used in a gas etching process and a plasma dicing process.

  After a circuit is formed on the surface of a semiconductor wafer, grinding is performed on the back side of the wafer, and a back grinding process for adjusting the thickness of the wafer and a dicing process for dividing the wafer into a predetermined chip size are performed. .

  In recent years, with the spread of IC cards and the rapid increase in capacity of USB memories, further reduction in thickness is desired as the number of stacked chips increases. For this reason, it is necessary to reduce the thickness of a semiconductor chip, which has conventionally been about 200 μm to 350 μm, to a thickness of 50 to 100 μm or less.

  On the other hand, as the necessity of stacking chips has increased for improving performance, the thinning of chips has progressed. However, the amount of chips used has increased accordingly, so an increase in the number of chips that can be manufactured in one process is desired. ing. On the other hand, the diameter of the wafer has been increased, and currently, processing is performed mainly on a 12 inch (300 mm) wafer. However, processing of 18-inch (450 mm) wafers has also been studied for further improving chip processing efficiency.

  FIGS. 3A and 3B are chip layout diagrams of the small-diameter semiconductor wafer 21 and the large-diameter semiconductor wafer 31. FIG. In the chip arrangement in which the chips 23 are arranged in a grid pattern as shown in FIG. 3A, dicing by a conventional dicing blade was possible. However, with a wafer diameter of 300 mm or more, when wiring is written on a large-sized chip such as a memory device, the area that cannot be used increases if patterning is performed on the wafer surface, and many chips cannot be used as products. To do. Therefore, in order to increase the yield of chips, the system is changing to a method in which the chips 33 are densely arranged on the outer peripheral portion of the semiconductor wafer 31 as shown in FIG. Since the conventional method of arranging the chips at equal intervals (FIG. 3A) is a method in which the chips are arranged in various directions (FIG. 3B) instead of the same direction, scribe (dicing) Line) is not a straight line, and linear dicing with a blade becomes difficult.

  In response to the above problems, dicing can be performed in cases other than straight lines using a laser or the like, and a dicing line is formed by selectively irradiating the inside of the semiconductor wafer with laser light to form a modified portion. A so-called stealth dicing method is proposed in which a semiconductor wafer is cut starting from the above (Patent Document 1). However, since the cutting of the chip with a laser damages the chip, there is a problem that the anti-deposition strength of the chip does not increase.

A method called plasma dicing has been proposed for the above problem (Patent Document 2). Plasma dicing is a method of dividing a semiconductor wafer by selectively etching a portion not covered with a mask with plasma. When this dicing method is used, the chip can be selectively divided, and even if the scribe line is bent, it can be divided without any problem. In addition, since the etching rate is very high, it has been regarded as one of the most suitable processes for chip cutting in recent years. However, in plasma dicing, a fluorine-based gas having a very high reactivity with a wafer, such as sulfur hexafluoride (SF ₆ ) or carbon tetrafluoride (CF ₄ ), is used as a plasma generating gas. From the etching rate, it is essential to protect the non-etched surface with a mask, and the mask must be masked with a resist or tape in advance. In addition, since the film remains after the plasma etching, a large amount of solvent is used for resist removal, and when the resist cannot be removed, adhesive residue is left, resulting in defective chips. Since the problem has not been solved, it is not popular.

  In the plasma dicing method, there is a problem that the wafer is exposed to plasma and generates heat and becomes high temperature, and the adhesive tape for protecting the semiconductor wafer is thermally deteriorated. The heat-degraded adhesive tape for protecting a semiconductor wafer does not use the adhesive tape for protecting a semiconductor wafer because the adhesive remains on the adherend or the peeling performance is lost.

On the other hand, recently, a processing method combining a gas cluster etching method in which the energy applied to the wafer is suppressed and the etching rate is controlled after the processing by the stealth dicing method described above has been proposed. Gas cluster etching is a method of processing a wafer by spraying gas toward a vacuum atmosphere to form a cluster of gas molecules and colliding with the wafer (Patent Document 3). The clusters that collide with the wafer give kinetic energy to the wafer, and then are decomposed and scattered as gas molecules. Thereby, the wafer surface can be etched. By performing this etching treatment after processing by the stealth dicing method, the modified portion by the laser is removed, and the bending strength can be expected to be improved. In the gas cluster etching method, chlorine trifluoride (ClF ₃ ) gas is used as a reactive gas, and since the bond of Cl—F is very small, plasma such as carbon tetrafluoride (CF ₄ ) is generated. Since it is not necessary to ionize in advance like the working gas, the damage to the substrate is extremely small, and protection with a mask is not required, and the chip can be easily cut.

  In the gas etching process using the gas cluster etching method or the like, as in the plasma dicing process, heat is generated due to a chemical reaction between the wafer and gas molecules when performing wafer processing. This heat generation may exceed 200 ° C., and in the processing method involving such heat generation, the base film is fused by heat to the chuck table holding the semiconductor wafer protection tape, or the base film shrinks. Therefore, it is necessary to prevent the semiconductor wafer from being damaged.

Japanese Patent Laid-Open No. 2003-33887 JP 2007-19386 A JP 2011-171484 A

  The present invention provides a heat-resistant and heat-shrinkable adhesive tape for protecting a semiconductor wafer that does not melt or shrink excessively even when exposed to high heat in a gas etching process or a plasma dicing process. The purpose is to provide.

In order to achieve the above-mentioned object, the following invention is provided.
(1) having a base film and an adhesive layer formed on one side of the base film;
The base film has a cast film layer containing a cured resin as an outermost layer on the side where the pressure-sensitive adhesive layer is not formed, and a speed of 30 mm when bringing a 3.0 mm diameter SUS304 probe into contact with a measurement sample. / Min, the contact load is 980 mN (100 gf) , and the contact time is 1 second. The cast film layer measured by the probe tack when the probe is peeled upward at a peeling rate of 600 mm / min. The peak value of the tack force of 100 kPa or less at 200 ° C. is a pressure-sensitive adhesive tape for protecting a semiconductor wafer.
(2) The adhesive tape for protecting a semiconductor wafer according to (1), wherein the base film consists only of a cast film layer.
(3) The adhesive tape for protecting a semiconductor wafer according to (1) or (2), wherein the cast film layer contains a cured acrylic copolymer or polyester resin.
(4) The said cast film layer is comprised with the acrylic copolymer hardened | cured with the hardening | curing agent or the radiation, For semiconductor wafer protection in any one of (1)-(3) characterized by the above-mentioned. Adhesive tape.
(5) The adhesive tape for protecting a semiconductor wafer according to any one of (1) to (4), wherein the breaking strength is 0.5 N / mm or more and the breaking elongation is 200% or more.
(6) Under the conditions that the speed at which a SUS304 probe having a diameter of 3.0 mm is brought into contact with the measurement sample is 30 mm / min, the contact load is 980 mN (100 gf) , and the contact time is 1 second, the probe is 600 mm / min. The peak value of the tack force of the pressure-sensitive adhesive layer measured by probe tack when peeled upward at a peeling rate of min is 50 to 400 kPa at 25 ° C. (1) to (5) The adhesive tape for semiconductor wafer protection in any one of.

  According to the present invention, even when exposed to high heat in a gas etching process or a plasma dicing process, the adhesive tape for protecting a semiconductor wafer has heat resistance and heat shrinkage resistance, and does not melt or shrink excessively to the chuck table. Can be provided.

(A) Sectional drawing which shows the adhesive tape 1 for semiconductor wafer protection which concerns on this embodiment, (b) Sectional drawing which shows the adhesive tape 1a for semiconductor wafer protection concerning this embodiment. The figure explaining the gas etching process using the adhesive tape 1 for semiconductor wafer protection which concerns on this embodiment. (A) Arrangement of chips on a small-diameter semiconductor wafer. (B) Arrangement | positioning drawing of the chip | tip in a large diameter semiconductor wafer.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1A is a cross-sectional view showing an adhesive tape 1 for protecting a semiconductor wafer according to this embodiment, and FIG. 1B is a cross-sectional view showing an adhesive tape 1a for protecting a semiconductor wafer according to this embodiment. is there.
The adhesive tape 1 for protecting a semiconductor wafer has a base film 3 and an adhesive layer 5 provided on the base film 3. Each layer may be cut (precut) into a predetermined shape in advance according to the use process and the apparatus. Further, the adhesive tape 1 for protecting a semiconductor wafer according to the present embodiment may be cut for each wafer, or may be a roll of a long sheet rolled up. Good. Below, the structure of each layer is demonstrated.

<Base film>
The base film 3 has a cast film layer 7 containing a cured resin as an outermost layer on the side where the pressure-sensitive adhesive layer 5 is not formed. 1A shows the base film 3 in which the cast film layer 7 and the resin film layer 9 are laminated. As long as the outermost layer is the cast film layer 7, the base film 3 has the resin film layer 9 on the base film 3. Other resin layers may be laminated.

  Since the cast film layer 7 uses a resin having a three-dimensional network structure by cross-linking, it is difficult to soften even when exposed to a high temperature and hardly cause fusion to the chuck table. In addition, since the cast film layer 7 is formed by coating, there is little residual stress, there is little thermal shrinkage even when exposed to high temperatures, and chip position misalignment hardly occurs in the gas etching process.

  In addition, as shown in FIG.1 (b), the base film 3 is comprised only by the cast film layer 7, and the adhesive tape 1a for semiconductor wafer protection which has the adhesive layer 5 on the single side | surface side of the cast film layer 7 is used. Also good. When the base film 3 is composed only of the cast film layer 7, the entire base film 3 is composed of the cast film. Therefore, the adhesive tape 1 a for protecting a semiconductor wafer includes the resin film layer 9, the cast film layer 7, and the like. Compared to the adhesive tape 1 for protecting a semiconductor wafer that uses the base film 3 laminated with the film, the adhesive tape has a low thermal shrinkage rate. Since the semiconductor wafer protecting adhesive tape 1a has a low thermal shrinkage rate, even in a gas etching process exposed to a high temperature, displacement of the position of a chip as an adherence hardly occurs and kerf shrink hardly occurs.

Moreover, the tack force of the cast film layer 7 is 100 kPa or less at 200 ° C., preferably 50 kPa, more preferably 30 kPa or less. The tack force here is a peak value of the tack force measured by the probe tack. When the tack force of the cast film layer 7 exceeds 100 kPa at 200 ° C., the cast film layer 7 tends to adhere to the chuck table when heated in a gas etching step or the like.
Moreover, it is preferable that the tack force of the cast film layer 7 is 20 kPa or less at 25 degreeC. When the tack force of the cast film layer 7 exceeds 20 kPa at 25 ° C., peeling from the chuck table at room temperature becomes worse. Further, when the pressure-sensitive adhesive tape is rolled, blocking may occur.

  Although there is no restriction | limiting in particular as the resin film 9, As a resin to be used, polyethylene, a polypropylene, ethylene-propylene copolymer, polybutene-1, poly-4-methylpentene-1, ethylene-vinyl acetate copolymer, ethylene -Acrylic acid copolymer, homopolymer or copolymer of α-olefin such as ionomer, or a mixture thereof, engineering plastics such as polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polyurethane, styrene-ethylene-butene or pentene copolymer A thermoplastic elastomer such as a polymer can be listed.

As thickness of the base film 3, it is preferable that it is 50-200 micrometers.
Moreover, when making the base film 3 into lamination | stacking of the resin film layer 9 and the cast film layer 7, as thickness of the cast film layer 7, it is preferable that it is 5-100 micrometers, and it is more preferable that it is 5-50 micrometers. preferable.
When a base film is comprised only by the cast film layer 7, it is preferable that the thickness of the cast film layer 7 is 50-200 micrometers, and it is more preferable that it is 50-100 micrometers.
Although there is no restriction | limiting in particular as the thickness of the resin film layer 9, Generally, it exists in the range of 50-150 micrometers.

  The cast film layer 7 is preferably composed of a coating of an acrylic polymer or a polyester resin composition and further curing with a curing agent or radiation. The cast film layer 7 formed by coating has less residual stress and less heat shrinkage even when exposed to high temperatures, compared to a stretched film formed by extrusion and further thinned by a stretching process. In addition, the cast film layer 7 according to the present embodiment has a three-dimensional network structure by cross-linking and has a small tack force at 200 ° C., and therefore does not fuse to the chuck table even when exposed to high temperatures.

  Moreover, it is preferable that the breaking strength of the adhesive tapes 1 and 1a for protecting a semiconductor wafer is 0.5 N / mm or more and the elongation at break is 200% or more. By providing such characteristics, problems such as breakage do not occur when sticking to or peeling off from a semiconductor wafer.

(Resin constituting the cast film layer)
The cast film layer 7 is formed of a cured resin, and is particularly formed of a resin obtained by curing an acrylic copolymer or a polyester resin. The acrylic polymer or polyester resin is not particularly limited, and an energy beam curable resin, a curing agent curable resin, a thermosetting resin, or the like is used, preferably an energy beam curable resin or a curing agent curable resin. Resin is used. When using an energy ray curable resin, the resin is cured by irradiating energy rays after coating. In the case of using a curing agent-curable resin, a crosslinking agent is added to the resin and cured by application and drying. When a thermosetting resin is used, the resin is cured by heating after application.

  When laminating the cast film layer 7 and the resin film layer 9, a method of applying a curable resin to the resin film layer 9 and curing it, or a method of adhering the cured cast film through an adhesive or the like Etc. In the case of obtaining a cast film layer 7 that is not laminated, the cast film layer 7 is obtained by applying a curable resin to a peelable film, then curing and peeling the film from the film.

(Acrylic copolymer)
The acrylic copolymer for forming the cast film layer 7 is not particularly limited. For example, when an energy ray curable resin is used, the acrylic copolymer and the energy ray polymerizable compound are the main components. . Specific examples of these acrylic pressure-sensitive adhesives and energy beam polymerizable compounds are as follows.

  The acrylic pressure-sensitive adhesive contains a (meth) acrylic copolymer and a curing agent as components. Examples of the (meth) acrylic copolymer include a polymer having (meth) acrylic acid ester as a polymer constituent unit, a copolymer of (meth) acrylic acid ester and a functional monomer, and these polymers. And the like. As the molecular weight of these polymers, those having a low molecular weight with a weight average molecular weight of about 10,000 to 200,000 are suitable from the viewpoint of stretchability of the base film.

  Moreover, a hardening | curing agent is used in order to make it react with the functional group which a (meth) acrylic-type copolymer has, and to adjust adhesive force and cohesion force. For example, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, 1,3-bis (N, N-diglycidylaminomethyl) toluene, 1,3-bis (N, N-diglycidylaminomethyl) ) Epoxy compounds having two or more epoxy groups in the molecule such as benzene, N, N, N, N'-tetraglycidyl-m-xylenediamine, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate , 1,3-xylylene diisocyanate, 1,4-xylene diisocyanate, diphenylmethane-4,4'-diisocyanate, etc., an isocyanate compound having two or more isocyanate groups in the molecule, tetramethylol-tri-β-aziridini Lupropionate, trimethylol-tri-β-aziridinylpropionate, Examples include aziridin compounds having two or more aziridinyl groups in the molecule, such as limethylolpropane-tri-β-aziridinylpropionate and trimethylolpropane-tri-β- (2-methylaziridine) propionate. . What is necessary is just to adjust the addition amount of a hardening | curing agent according to desired adhesive force, and 0.1-5.0 mass parts is suitable with respect to 100 mass parts of (meth) acrylic-type copolymers.

  In the case of using a curing agent-curable resin, in order to suppress tack force and ensure strength and elongation as a film, the functional group reacts with the curing agent in the (meth) acrylic copolymer. It is desirable to add an equal amount of curing agent, for example, 2.0 to 30 parts by mass is appropriate for 100 parts by mass of the (meth) acrylic copolymer

  The energy ray curable resin generally contains the acrylic pressure-sensitive adhesive and the energy ray polymerizable compound as main components. As the energy ray polymerizable compound, for example, a low molecular weight compound having at least two photopolymerizable carbon-carbon double bonds in a molecule that can be three-dimensionally reticulated by ultraviolet irradiation is widely used. Specifically, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, 1,4-butylene glycol diacrylate, 1,6 hexanediol diacrylate, polyethylene glycol diacrylate, oligoester acrylate, and the like are widely applicable.

  In addition to the acrylate compounds as described above, urethane acrylate oligomers can also be used as the acrylic pressure-sensitive adhesive. The urethane acrylate oligomer includes a polyol compound such as a polyester type or a polyether type, and a polyvalent isocyanate compound (for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diene). A terminal isocyanate urethane prepolymer obtained by reacting isocyanate, 1,4-xylylene diisocyanate, diphenylmethane 4,4-diisocyanate, etc.) with an acrylate or methacrylate having a hydroxyl group (for example, 2-hydroxyethyl) Acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, polyethylene glycol acrylate, polyethylene glycol methacrylate, etc.) Obtained by the reaction.

As a compounding ratio of the acrylic pressure-sensitive adhesive and the energy beam polymerizable compound in the energy ray curable resin, the energy ray polymerizable compound is 50 to 200 parts by mass, preferably 50 to 100 parts by mass with respect to 100 parts by mass of the acrylic pressure-sensitive adhesive. It is desirable to blend in the range of 150 parts by mass. In the case of this blending ratio range, the tack force of the energy beam curable resin is greatly reduced after the energy beam irradiation.
Furthermore, the energy ray curable resin may be an energy ray polymerizable acrylate copolymer instead of blending the energy ray polymerizable compound with the acrylic adhesive as described above. Is possible.

  In the case of polymerizing an energy ray curable resin by energy rays, a photopolymerization initiator such as isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, Michler's ketone, chlorothioxanthone, benzyl methyl ketal, α-hydroxycyclohexyl phenyl ketone, 2-hydroxymethylphenylpropane or the like can be used in combination. By adding at least one of these to the energy ray curable resin, the polymerization reaction can be efficiently advanced. The energy beam referred to here refers to a light beam such as an ultraviolet ray or an ionizing energy beam such as an electron beam.

(Polyester resin)
The polyester resin for forming the cast film layer 7 is not particularly limited. For example, when a curing agent curable resin is used, a curing agent curable polyester resin composition and a curing agent are used as main components.

The curing agent-curable polyester resin composition is a composition containing a polyester resin having a functional group capable of reacting with a curing agent, and preferably a polyester polyol having a hydroxyl group can be used.
Moreover, a hardening | curing agent reacts with the functional group which a hardening | curing agent hardening type polyester resin composition has, and is used in order to adjust adhesive force and cohesion force. Preferably, an isocyanate compound having two or more isocyanate groups in the molecule can be used.

<Adhesive layer>
The pressure-sensitive adhesive layer 5 can be formed by applying a pressure-sensitive adhesive to the base film 3. The pressure-sensitive adhesive layer 5 constituting the semiconductor wafer protecting pressure-sensitive adhesive tape 1 according to the present embodiment only needs to have a retaining property that does not cause separation from the chip during the gas etching step. In addition, it is desirable that the amount of outgas is small so as not to contaminate the wafer and the apparatus during heating.

  In particular, the tack force of the pressure-sensitive adhesive layer 5 before being irradiated with energy rays or the like is preferably 50 to 400 kPa at 25 ° C. Such tack force does not cause separation between the semiconductor wafer and the chip that are the adherends.

  In the present embodiment, the configuration of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 5 is not particularly limited, but in order to improve the peelability, an energy ray curable material is preferable, and peeling from the chip 21 is facilitated after curing. A material is preferred. As a pressure-sensitive adhesive having energy ray curability, for example, a pressure-sensitive adhesive composition having an acrylic pressure-sensitive adhesive used for forming the cast film layer 7 and an energy ray polymerizable compound as main components can be used. When an energy ray curable adhesive is used, energy ray curing may be performed before the gas etching step in order to increase heat resistance.

<Application>
The adhesive tape 1 for protecting a semiconductor wafer according to the present embodiment is suitably used for an etching process step using a gas to chips separated by a stealth dicing step.

(Gas etching process)
A method for using the tape when the adhesive tape 1 for protecting a semiconductor wafer according to the present embodiment is applied to a gas etching step will be described with reference to FIG.

  FIG. 2 is a cross-sectional view showing a gas etching process in which etching is performed on the chip 11 from which the semiconductor wafer has been separated into pieces by the stealth dicing process. As shown in FIG. 2, a plurality of chips 11 in which a semiconductor wafer is separated into pieces by a stealth dicing process are fixed to the adhesive tape for protecting a semiconductor wafer fixed to the ring frame 15. The chip 11 is held by a chuck table 17. Thereafter, the etching gas 13 is irradiated to etch the exposed surface of the chip 11.

The modified region by the laser beam remaining in the chip cross section is removed by the gas etching process. Since the modified region is brittle, if the modified region remains on the chip 11, the chip 11 is broken from the modified region. The bending strength of the chip 11 is increased by removing the modified region and the unevenness on the surface of the chip 11. An example of gas etching is a method in which chlorine trifluoride (ClF ₃ ) gas heated to 200 ° C. is blown into a chamber whose pressure is reduced to about 1 kPa at a pressure of 0.3 to 2.0 MPa.

  At this time, the heated etching gas 13 is irradiated, or a chemical reaction occurs between the etching gas 13 and the chip 11, whereby the semiconductor wafer protecting adhesive tape 1 is heated. The portion in contact with the chuck table 17 is cooled by circulating cooling water through the chuck table 17. However, when the portion where the chuck table 17 does not contact or the generated heat exceeds the cooling, the adhesive tape 1 for protecting the semiconductor wafer is , It may be heated to about 200 ° C.

(Effect according to this embodiment)
In this embodiment, since the tack force is below a predetermined value even when the cast film layer 7 in contact with the chuck table 17 is heated to 200 ° C., the adhesive tape 1 for protecting a semiconductor wafer according to this embodiment is the chuck table 17. Gas etching is possible without fusing.

  Moreover, in this embodiment, since the base film 3 has the cast film layer 7, the thermal contraction rate of the adhesive tape for semiconductor wafer protection becomes small, and the position of the chip is shifted or the chips are in contact in the gas etching process. Can be prevented.

  In particular, in this embodiment, when forming a base film only with a cast film layer, the heat shrinkage rate of the adhesive tape for protecting a semiconductor wafer is further reduced.

  Next, in order to further clarify the effects according to the present embodiment, examples and comparative examples will be described in detail, but the present invention is not limited to these examples.

[Production of adhesive tape for semiconductor wafer protection]
(1) Production of base film (laminated film of cast film A and resin film A)
A resin film A having a thickness of 100 μm was formed by T-die method using Sumitomo Chemical's ethylene methyl methacrylate (EMMA) resin “Aclift WD201 (trade name)”.
The UV curable acrylic copolymer A is coated on the release film so that the thickness after drying is 30 μm, and is bonded to the resin film A, irradiated with UV light, and cured to have a total thickness of 130 μm. A laminated film of resin film A and cast film A was obtained.

Composition of UV curable acrylic copolymer composition A is as follows: Acrylic ester copolymer 100 parts by mass Curing agent ("Coronate L" (trade name) manufactured by Nippon Polyurethane) 2 parts by mass Radiation polymerizable Compound 150 parts by mass Photopolymerization initiator ("Irgacure 184" (trade name) manufactured by Ciba Geigy Japan) 5 parts by mass

The acrylic ester copolymer and the radiation polymerizable compound are as follows.
Acrylic ester copolymer:
A copolymer obtained by copolymerizing 2-ethylhexyl acrylate, methyl acrylate, and 2-hydroxyethyl acrylate, having a weight average molecular weight of 100,000 and a glass transition point of -10 ° C.
Radiation polymerizable compounds:
Urethane acrylate oligomer with a weight average molecular weight of 1100

(Cast film B)
The curing agent-curable polyester resin composition is coated on a release film, dried, bonded to another release film, cured and cured for 1 week, and then peeled off from the release film. Got. The thickness of the cast film B after drying was 70 μm.

The composition of the curing agent-curable polyester resin composition is as follows: Polyester resin composition (weight average molecular weight: 15,000, glass transition point: 40 ° C.) 100 parts by mass Curing agent (Nippon Polyurethane “Coronate L” (Product name)) 10 parts by mass

(Resin film B)
A 100 μm polyethylene terephthalate film (manufactured by Teijin DuPont Films, G2: trade name) was used as the resin film B.

(2) Preparation of pressure-sensitive adhesive composition A In 400 g of toluene as a solvent, a mixed solution of 446.5 g of 2-ethylhexyl acrylate, 45 g of methyl methacrylate, 3.4 g of methacrylic acid, and 0.5 g of benzoyl peroxide as a polymerization initiator was added. While dripping over time, it was made to react at the temperature of 100 degreeC for 4 hours, and the solution of the polymer (2) which has a functional group was obtained. Next, to this polymer solution (2), as a compound (1) having a photopolymerizable carbon-carbon double bond and a functional group, 5.1 g of 2-hydroxyethyl methacrylate and 0.1 g of hydroquinone as a polymerization inhibitor are added, After reacting for 6 hours at a temperature of 120 ° C., the solution was neutralized with acetic acid to obtain a solution of the compound (A). 1 part by mass of polyisocyanate (manufactured by Nippon Polyurethane Co., Ltd .: Coronate L) (B), photopolymerization initiator (Irgacure 184, manufactured by Ciba Geigy Japan) 0 to 100 parts by mass of compound (A) in the compound (A) solution .5 parts by mass was added to the compound (A) solution and mixed to prepare an acrylic energy ray-curable pressure-sensitive adhesive composition A.

<Example 1>
The pressure-sensitive adhesive composition A prepared on the resin film A side of the film obtained by laminating the cast film A and the resin film A was applied and dried to prepare an adhesive tape for protecting a semiconductor wafer.

<Example 2>
The adhesive composition A was applied to the cast film B and dried to prepare an adhesive tape for protecting a semiconductor wafer.

<Comparative Example 1>
The adhesive composition A was applied to the resin film A and dried to prepare an adhesive tape for protecting a semiconductor wafer.

<Comparative example 2>
The adhesive composition A was applied to the resin film B and dried to prepare an adhesive tape for protecting a semiconductor wafer.

[Physical properties and evaluation of adhesive tape for semiconductor wafer protection]
(1) Measurement of tack force It was carried out using a tacking tester TAC-II from Reska Co., Ltd. As the measurement mode, Constant Load was used in which the probe was pushed down to the set pressure value and kept controlled until the set time passed. After the separator was peeled off, the base film was placed on the plate with the side where the pressure-sensitive adhesive layer was not formed facing up, and a probe made of SUS304 having a diameter of 3.0 mm was contacted from above. The speed at which the probe is brought into contact with the measurement sample is 30 mm / min, the contact load is 980 mN (100 gf) , and the contact time is 1 second. Thereafter, the probe was peeled upward at a peeling speed of 600 mm / min, the force required for peeling was measured, and the peak value was taken as the tack force. In accordance with the temperature at which the tack force is to be measured, for example, the tack force at 200 ° C. was set at 200 ° C. for the probe and plate temperatures.

(2) Evaluation in gas etching process Adhesive tape for processing semiconductor wafers is bonded to a mirror wafer with a diameter of 6 inches and a thickness of 100 μm, and a 6-inch wafer is diced into a 10 mm square from the wafer surface. 20 μm), a semiconductor wafer processing adhesive tape is adsorbed to the chuck table in a vacuum chamber, and ClF ₃ gas etching is performed for 30 seconds. At this time, hot water at 70 ° C. is passed through the chuck table to cool the semiconductor wafer processing adhesive tape and the wafer. After this step, it was evaluated whether the adhesive tape could be easily peeled from the chuck table.
○ and X in the table mean the following.
“○”: The adhesive tape could be easily peeled off from the chuck table after the gas etching step. “×” —The adhesive tape could not be easily peeled off from the chuck table after the gas etching step. Or the adhesive tape broke and melted.

(3) Chip shift evaluation For those that could be processed and peeled off from the chuck table by gas etching evaluation, the chip interval due to dicing was not shifted in the gas etching process. Confirmed. For example, when the interval between chips after the gas etching step is 22 μm with respect to the cut width of 25 μm by dicing, the deviation is 3 μm. ◎ if the deviation was within ± 1μm in all locations, ○ if the deviation was within ± 2.5μm in all locations, ○ if the deviation was ± 2.5μm or more in one of the five locations Was x.

(4) Breaking strength, breaking elongation The pressure-sensitive adhesive tape was punched out with a No. 1 dumbbell shape (JIS K 6301) to prepare a test piece, and measured using a tensile test apparatus (JIS B 7721). After putting a 40 mm marked line into the test piece, the load (tensile strength) and elongation at the time of cutting between marked lines were measured using a tensile tester. However, the tensile speed was 300 mm / min.

  As shown in Table 1, in the adhesive tapes for protecting semiconductor wafers of Examples 1 and 2, the side where the adhesive layer is not formed is the cast film layers A to B, and the tack force of the outermost layer is 100 kPa or less even at 200 ° C. Therefore, the base film of the adhesive tape was not fused to the chuck table in the gas etching process.

  In particular, in Example 2, since the base film was only a cast film, the shrinkage was small even by heating, and the chip shift was further reduced during the gas etching process.

  In Comparative Example 1, since the outermost layer on the side where the adhesive of the base film is not formed is the resin film A, the base film of the adhesive tape is fused to the chuck table in the gas etching step. It was difficult to peel off the base film from the chuck table after the gas etching step.

  In Comparative Example 2, the tack force of the outermost layer on the side on which the adhesive of the base film was not formed was 100 kPa or less even at 200 ° C., but it was shrunk due to the residual stress at the time of film forming due to the influence of heating in the etching process. However, since the adhesive tape floated from the chuck table and was not cooled by the chuck table, discoloration of the wafer and deterioration of the adhesive were observed.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the technical idea disclosed in the present application, and these are naturally within the technical scope of the present invention. Understood.

DESCRIPTION OF SYMBOLS 1, 1a ......... Adhesive tape 3 for semiconductor wafer protection ......... Base film 5 ......... Adhesive layer 7 ......... Cast film layer 9 ......... Resin film layer 11 ......... Chip 13 ......... Etching Gas 15 ......... Ring frame 17 ......... Chuck table 21 ......... Semiconductor wafer 23 ......... Chip 31 ......... Semiconductor wafer 33 ......... Chip

Claims (6)

Having a base film and an adhesive layer formed on one side of the base film,
The base film has a cast film layer containing a cured resin in the outermost layer on the side where the pressure-sensitive adhesive layer is not formed,
The probe was peeled off at 600 mm / min under the conditions that the speed when contacting a probe made of SUS304 having a diameter of 3.0 mm to the measurement sample was 30 mm / min, the contact load was 980 mN (100 gf) , and the contact time was 1 second. A pressure-sensitive adhesive tape for protecting a semiconductor wafer, wherein a peak value of tack force of the cast film layer measured by probe tack when peeled upward at a speed is 100 kPa or less at 200 ° C.   The adhesive tape for protecting a semiconductor wafer according to claim 1, wherein the base film consists only of a cast film layer.   The adhesive tape for protecting a semiconductor wafer according to claim 1 or 2, wherein the cast film layer contains a cured acrylic copolymer or polyester resin.   The said cast film layer is comprised with the acrylic copolymer hardened | cured with the hardening | curing agent or the radiation, The adhesive tape for semiconductor wafer protection of any one of Claims 1-3 characterized by the above-mentioned.   The adhesive strength tape for protecting a semiconductor wafer according to any one of claims 1 to 4, wherein the breaking strength is 0.5 N / mm or more, and the breaking elongation is 200% or more. The probe was peeled off at 600 mm / min under the conditions that the speed when contacting a probe made of SUS304 having a diameter of 3.0 mm to the measurement sample was 30 mm / min, the contact load was 980 mN (100 gf) , and the contact time was 1 second. The peak value of the tack force of the pressure-sensitive adhesive layer measured by probe tack when peeled upward at a speed is 50 to 400 kPa at 25 ° C. 6. The adhesive tape for semiconductor wafer protection as described in 2.

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