WO2016056269A1 - Adhesive tape for protecting semiconductor wafer surface and method for processing semiconductor wafer - Google Patents

Abstract

Provided is an adhesive tape for protecting a semiconductor wafer surface having bumps, said adhesive tape having an ultraviolet curable adhesive layer on a substrate film, wherein the adhesive layer comprises a (meth)acrylic polymer having a weight average molecular weight of 10,000 to 2,000,000 and a radiation curable carbon-carbon double bond-containing group, a hydroxyl group and a carboxy group; the surface free energy of the adhesive layer surface before ultraviolet irradiation is at least 25.5 mN/m and less than 35 mN/m; the surface of the adhesive layer after having been cured with ultraviolet irradiation has a surface free energy that is at least 5 mN/m higher than that of the surface of the adhesive layer before ultraviolet irradiation and has a small contact angle with respect to diiodomethane; the polymer constituting the adhesive layer surface having a hydroxyl value of 30-100 mg KOH/g; and the polymer constituting the adhesive layer surface has an acid value of 5-65 mg KOH/g. Also provided is a method for processing a semiconductor wafer having bumps.

Description

Adhesive tape for protecting semiconductor wafer surface and method for processing semiconductor wafer

The present invention relates to an adhesive tape for protecting a semiconductor wafer surface and a method for processing a semiconductor wafer. More specifically, the present invention relates to an adhesive tape for protecting the surface of a semiconductor wafer used when grinding the semiconductor wafer into a thin film and a method for processing the semiconductor wafer.

A semiconductor package is manufactured by slicing a high-purity silicon single crystal or the like into a semiconductor wafer, and then forming an integrated circuit on the wafer surface by ion implantation, etching, or the like. By grinding or polishing the back surface of the semiconductor wafer on which the integrated circuit is formed, the semiconductor wafer is processed into a desired thickness. At this time, in order to protect the integrated circuit formed on the surface of the semiconductor wafer, a semiconductor wafer surface protective adhesive tape (hereinafter also simply referred to as “surface protective tape”) is used.
The back-ground semiconductor wafer is accommodated in a wafer cassette after the back-side grinding is completed, transported to a dicing process, and processed into semiconductor chips.

Conventionally, it has been required that the thickness of the semiconductor wafer be about 200 to 400 μm by back grinding or the like. However, with recent progress in high-density mounting technology, it is necessary to reduce the size of semiconductor chips, and the semiconductor wafers are becoming thinner. Depending on the type of semiconductor chip, it is necessary to make the semiconductor wafer as thin as about 100 μm. Also, large wafers tend to be used to increase the number of semiconductor chips that can be manufactured by a single process. Until now, wafers with diameters of 5 inches and 6 inches have been mainstream, but in recent years, processing of semiconductor wafers with diameters of 8 to 12 inches into semiconductor chips has become mainstream.
The trend of thinning and increasing the size of semiconductor wafers is particularly remarkable in the field of flash memory where NAND type and NOR type exist, and in the field of DRAM, which is a volatile memory. For example, it is not uncommon to grind a 12-inch diameter semiconductor wafer to a thickness of 150 μm or less.

Usually, a semiconductor wafer is taken out one by one from a dedicated case called a wafer cassette by a robot arm, held by a semiconductor wafer fixing jig in a grinding machine, and backside grinding is performed. The back-ground semiconductor wafer is stored in a wafer cassette by a robot arm and transferred to the next process. At this time, if the warp of the semiconductor wafer is large, problems such as suction failure may occur, and in the worst case, the wafer may fall off the suction arm during the transfer and fall. However, this problem is being solved by the advent of a thin film grinding machine called an inline system and the development of a special tape (for example, see Patent Documents 1 and 2). Therefore, it is considered that the trend toward thin film wafers will accelerate further in the future.

The wafer after grinding is mounted on a dicing tape or a dicing die bonding film, and then the surface protection tape is peeled off. When grinding the back surface of a large semiconductor wafer to make the wafer thin, if the surface protective tape that is applied to the front surface of the wafer is not restrained, the load applied to the wafer when the surface protective tape is peeled off It takes too much and the wafer breaks easily.

Also, in order to improve the performance of discrete wafers, the film thickness is gradually increasing. Since these discrete wafers are subjected to special surface treatments and various surface step sizes, it is easy for adhesive residue to remain when the surface protection tape is peeled off, and improving peelability is a major issue. It has become one.

The surface protection tape is required to have a high wafer holding force in the grinding process on the backside of the wafer and to have a low adhesive force during peeling. Therefore, conventionally, a tape having an ultraviolet curable pressure-sensitive adhesive layer has been widely used as a surface protective tape. A surface protection tape having an ultraviolet curable pressure-sensitive adhesive layer can be bonded to a semiconductor wafer in a state having a high adhesive force, and thus has excellent adhesion and high wafer holding power. On the other hand, since it hardens | cures and can reduce adhesive force by irradiating an ultraviolet-ray before peeling, peelability is also improved. (For example, refer to Patent Document 3).

However, since the ultraviolet curable pressure-sensitive adhesive layer is highly reactive, if the wafer surface is modified, the components of the pressure-sensitive adhesive layer may react with the wafer surface to cause peeling failure or wafer cracking. In addition, an insulating resin layer containing polyimide or the like and a conductor wiring pattern may be provided on the wafer surface. However, if an insulating resin layer is present on the wafer surface, the adhesive strength of the surface protection tape increases and the peelability decreases.
Under such circumstances, as a method for improving the peelability of the surface protection tape from the semiconductor surface, Patent Document 4 discloses that the property of the pressure-sensitive adhesive layer surface is adjusted using the contact angle with diiodomethane (methylene iodide) as an index. It is described to do.

Furthermore, as a method for improving the peelability of the surface protection tape from the semiconductor surface, Patent Document 5 describes not only the contact angle with diiodomethane (methylene iodide) but also the surface free energy of the pressure-sensitive adhesive layer. It is described that it is adjusted as an index.

JP 2011-151355 A JP 2003-261842 A JP-A-9-298173 JP 2009-242776 A International Publication No. 2013/122060 Pamphlet

However, as described in Patent Document 4, when the surface of the adhesive layer of the surface protection tape is made to have a specific property and the peelability from the semiconductor wafer is enhanced, the semiconductor wafer may be used during a transport process or storage in a wafer cassette. In some cases, the outer peripheral portion (edge) of the film is easily peeled off from the tape (that is, the edge is liable to be lifted). When edge lifting occurs, there is a risk that edge cracking or wafer cracking may occur due to pressure applied by a roller during pasting of the dicing tape. In addition, when the surface protective tape is applied to a semiconductor wafer with bumps (electrodes), sufficient adhesion to the wafer surface having the bumps may not be obtained. Air (air) becomes easy to mix.

On the other hand, since the surface protection tape described in Patent Document 5 omits an ultraviolet irradiation process that is complicated in process management, the pressure-sensitive adhesive used for the pressure-sensitive adhesive layer is pressure-sensitive. For this reason, in Patent Document 5, attention is not paid to the improvement of the radiation curable surface protective tape in which the pressure-sensitive adhesive used in the pressure-sensitive adhesive layer is ultraviolet rays or the like.

The present invention has excellent adhesion even when applied to an uneven surface of a semiconductor wafer with bumps, is less likely to cause edge lifting, and there is an insulating layer or conductor wiring pattern on the surface protective tape bonding surface of the semiconductor wafer. Even if it is a case, it can be easily peeled without damaging the wafer, there is little adhesive residue on the wafer surface after peeling, the pressure sensitive adhesive used for the pressure sensitive adhesive layer is a radiation curable adhesive tape for semiconductor wafer surface protection, It is another object of the present invention to provide a method for processing a semiconductor wafer using the tape.

The present inventors have intensively studied in view of the above problems. As a result, when the UV curable adhesive has the property that the surface free energy increases after UV irradiation and the contact angle of diiodomethane is reduced, it is sufficient even on uneven surfaces such as semiconductor wafers with bumps. Adhesion and edge lift are unlikely to occur, and even if an insulating layer or conductor wiring pattern is present on the surface of the semiconductor wafer, the tape can be easily peeled off from the semiconductor wafer. The adhesive residue on the wafer surface was found to be suppressed. The present invention has been further studied based on these findings and has been completed.

That is, the gist of the present invention is as follows.
(1) A bumped semiconductor wafer surface protecting adhesive tape having an ultraviolet curable adhesive layer on a substrate film,
The pressure-sensitive adhesive layer contains a (meth) acrylic polymer having a weight average molecular weight of 10,000 to 2,000,000 and having a radiation-curable carbon-carbon double bond-containing group, a hydroxyl group, and a carboxy group.
The surface free energy of the pressure-sensitive adhesive layer surface before ultraviolet irradiation is 25.5 mN / m or more and less than 35 mN / m,
The surface of the pressure-sensitive adhesive layer after curing by ultraviolet irradiation has a surface free energy higher by 5 mN / m or more than the surface of the pressure-sensitive adhesive layer before ultraviolet irradiation,
The surface of the pressure-sensitive adhesive layer after curing by ultraviolet irradiation has a smaller contact angle with respect to diiodomethane than the surface of the pressure-sensitive adhesive layer before ultraviolet irradiation,
The (meth) acrylic polymer is obtained by reacting a polymer having a hydroxyl group and a carboxy group before introduction of a radiation-curable carbon-carbon double bond group with a compound having a radiation-curable carbon-carbon double bond group. 1 mol% to 10 mol% of (meth) acrylic acid in all the monomer components forming the polymer before the introduction of the radiation curable carbon-carbon double bond group,
The hydroxyl value of the polymer constituting the pressure-sensitive adhesive layer surface is 30 to 100 mgKOH / g,
A pressure-sensitive adhesive tape for protecting a semiconductor wafer with bumps, wherein an acid value of a polymer constituting the surface of the pressure-sensitive adhesive layer is 5 to 65 mgKOH / g.
(2) The bumped semiconductor wafer surface protecting pressure-sensitive adhesive tape according to (1), wherein the compound having a radiation-curable carbon-carbon double bond group is 2- (meth) acryloyloxyethyl isocyanate .
(3) The amount of the 2- (meth) acryloyloxyethyl isocyanate is 1 part by mass to 20 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer. Bumped semiconductor wafer surface protective adhesive tape.
(4) The bumped semiconductor according to any one of (1) to (3), wherein a crosslinking agent is added in an amount of 0.1 to 5 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer. Adhesive tape for wafer surface protection.
(5) The bumped semiconductor wafer surface protecting device according to any one of (1) to (4), wherein the acid value of the polymer constituting the pressure-sensitive adhesive layer surface is 10 to 35 mgKOH / g Adhesive tape.
(6) A method for processing a bumped semiconductor wafer using the bumped semiconductor wafer surface protecting adhesive tape according to any one of (1) to (5), comprising the following steps (A) to (D): A method for processing a semiconductor wafer with bumps, comprising:
Step (A) Step of bonding the bumped semiconductor wafer surface protecting adhesive tape to the bump-formed surface of the semiconductor wafer with bumps Step (B) For protecting the bumped semiconductor wafer surface of the semiconductor wafer with bumps Step of grinding the surface opposite to the bonding surface of the adhesive tape Step (C) Step of curing the bumped semiconductor wafer surface protecting adhesive tape by irradiating the bumped semiconductor wafer surface protecting adhesive tape with ultraviolet rays And (D) peeling the bumped semiconductor wafer surface protecting adhesive tape from the bumped semiconductor wafer (7) bonding the bumped semiconductor wafer with the bumped semiconductor wafer surface protecting adhesive tape. The method for processing a semiconductor wafer with bumps according to (6), wherein an insulating layer is provided on the surface.
(8) The method for processing a semiconductor wafer with bumps according to (6) or (7), wherein the height of the bumps is 15 μm or more.

In the present specification, the term “surface of the pressure-sensitive adhesive layer” or “surface of the pressure-sensitive adhesive layer” means a surface opposite to the bonding surface of the base film unless otherwise specified.
In this specification, bonding a semiconductor wafer surface protective adhesive tape to a semiconductor wafer means bonding the adhesive layer surface toward the semiconductor wafer surface.
In this specification, the term “(meth) acryl” is used to mean including one or both of acrylic and methacrylic. The same applies to the terms “(meth) acryloyl” and “(meth) acrylamide”.

Even when the adhesive tape for protecting a semiconductor wafer surface of the present invention is applied to an uneven surface of a bumped semiconductor wafer such as a solder bump or a gold bump, the air is hardly mixed and the adhesiveness is excellent, and the edge is hardly lifted. Moreover, the adhesive tape for protecting the surface of a semiconductor wafer of the present invention is excellent in releasability, and even when it is bonded to the surface of a large semiconductor wafer and the back surface of the wafer is ground and processed into a thin film wafer of 100 μm or less, the wafer is damaged. Can be easily peeled off, and adhesive residue on the wafer surface after peeling can be suppressed. In addition, good peelability is also exhibited for those having an insulating layer or a conductor wiring pattern on the surface of the semiconductor wafer surface protecting adhesive tape.
Therefore, the adhesive tape for protecting the surface of a semiconductor wafer according to the present invention is applied to a semiconductor wafer having a relatively large surface difference, such as a discrete wafer, a semiconductor wafer with a bump electrode comprising an insulating layer and a conductor wiring pattern, and a flip chip mounting method. It is suitable as an adhesive tape for surface protection such as a solder bump or a semiconductor wafer with a gold bump.
Moreover, according to the semiconductor wafer processing method of the present invention, a thin film semiconductor wafer can be obtained with a high yield. That is, the semiconductor wafer processing method of the present invention is suitable as a method for manufacturing a thin film semiconductor wafer.

The above and other features and advantages of the present invention will become more apparent from the following description with reference to the accompanying drawings as appropriate.

FIG. 1 is a cross-sectional view showing an embodiment of the adhesive tape for protecting a semiconductor wafer surface according to the present invention.

<< Semiconductor wafer surface protective adhesive tape >>
A preferred semiconductor wafer surface protecting pressure-sensitive adhesive tape of the present invention (hereinafter simply referred to as “the pressure-sensitive adhesive tape of the present invention”) of the present invention will be described with reference to the drawings. As shown in a schematic cross-sectional view in FIG. 1, the pressure-sensitive adhesive tape 10 of the present invention is used by forming a pressure-sensitive adhesive layer 12 on at least one surface of a base film 11 and bonding the pressure-sensitive adhesive layer 12 to a semiconductor wafer 13. .

Hereinafter, embodiments of the present invention will be described in detail.

<Adhesive layer>
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the present invention may be a single layer or a multilayer structure in which two or more types of pressure-sensitive adhesive layers having different compositions are laminated. It is preferable that at least the surface of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the present invention is ultraviolet curable, and all the pressure-sensitive adhesive layers are ultraviolet curable. In the pressure-sensitive adhesive tape of the present invention, the surface of the pressure-sensitive adhesive layer after curing by ultraviolet irradiation has a surface free energy higher by 5 mN / m or more than the surface of the pressure-sensitive adhesive layer before ultraviolet irradiation, and the surface of the pressure-sensitive adhesive layer before ultraviolet irradiation. Is smaller in contact angle with diiodomethane (CH ₂ I ₂ ).

(Surface free energy on the adhesive layer surface)
In the present invention, the surface free energy of the pressure-sensitive adhesive layer surface is a value obtained by using the Owens and Wendt method, and the contact angle of the pressure-sensitive adhesive layer surface with pure water and diiodomethane is measured (droplet volume: pure water). 2 μL, 3 μL of diiodomethane, reading time: 30 seconds after dropping, measurement atmosphere: temperature 23 ° C., relative humidity 50%), and solving the simultaneous equations of the following formula 1. The “solid surface” in the following refers to the pressure-sensitive adhesive layer surface in this specification.

Here, in the formula (1) is Fowkes-Owens type, surface which was divided component of free energy, the surface free energy gamma _s is the polar component of the surface free energy gamma _s ^p (London forces only) and surface free energy Of the dispersion component γ _s ^d (including Debye force and hydrogen bonding force). The above formulas (2a) and (2b) are relational expressions obtained by combining Young's formula with the relational expression of the extended Fowkes model for the interfacial tension γsl of the interface such as the solid s and the liquid l. Expression (2a) is a relational expression in the case of pure water, and Expression (2b) is a relational expression in the case of diiodomethane.
The surface tension γ _l , the surface tension polar component γ _l ^p , and the surface tension dispersion component γ _l ^d of pure water are 72.8 mN / m, 51.0 mN / m, and 21.8 mN / m, respectively. The surface tension γ _l , surface tension polar component γ _l ^p , and surface tension dispersion component γ _l ^d are 50.8 mN / m, 2.3 mN / m, and 48.5 mN / m, respectively. These values are incorporated in 2a) and (2b).

Note that, since pure water and diiodomethane have different polar components and dispersed components, the surface tensions are different as described above. This is because pure water and diiodomethane differ in the presence or absence of hydrogen bonds and the difference in electronegativity, and the polarities differ greatly accordingly. In particular, in the case of water, hydrogen bonds such as —OH and —O— are strong, and the proportion of polar components is large.

In the pressure-sensitive adhesive, the polar component can be changed by adding a hydroxyl group or a carboxy group to the polymer. Thereby, since the contact angle with respect to water changes, surface free energy can be changed. When the adhesive tape is peeled off, if the adhesive remains due to insufficient aggregation, the dispersed component is dominant, and if the adhesive remains on the surface subjected to special activation treatment, the polar component is dominant. Guessed. Therefore, in order to solve the problem of adhesive residue on surfaces having various properties, it is important to control the contact angle with water or diiodomethane, that is, the surface free energy on the surface of the pressure-sensitive adhesive layer.

An ultraviolet curable pressure sensitive adhesive has a reduced adhesive strength when irradiated with ultraviolet light, thereby improving the peelability from the semiconductor wafer. Thus, unlike the pressure-sensitive adhesive layer, the UV curable adhesive layer undergoes changes in physical properties and structure of the adhesive layer before and after UV irradiation.

Since the ultraviolet curable pressure-sensitive adhesive layer usually contains a photopolymerization initiator, it may react and adhere to the wafer surface, for example, under the influence of heat or light even before ultraviolet curing. This adhesion causes glue residue at the time of peeling. By suppressing the surface free energy of the surface of the pressure-sensitive adhesive layer before UV curing to a certain level, the present inventors suppress the reaction before UV irradiation while maintaining the adhesiveness, and the wafer and the pressure-sensitive adhesive tape over time It has been found that adhesion of can be prevented.
On the other hand, it has been found by the present inventors that after the irradiation with ultraviolet rays, even if the surface free energy on the surface of the pressure-sensitive adhesive layer is high to some extent, peeling failure is unlikely to occur. This is because the adhesive is cured by UV irradiation and the adhesive strength is lowered, and the photopolymerization initiator is consumed by the curing reaction by UV irradiation, so that the reactivity with the wafer surface is reduced. It is thought that. Furthermore, the present inventors have found that the surface free energy on the surface of the pressure-sensitive adhesive layer after ultraviolet irradiation is increased to a certain extent, so that edge lifting can be effectively prevented during conveyance in the apparatus and cassette storage. When the edge float occurs, as described above, the edge crack is likely to occur due to the pressure by the roller at the time of dicing tape bonding, and in the worst case, the wafer crack occurs.
In the pressure-sensitive adhesive tape of the present invention, the surface free energy on the surface of the pressure-sensitive adhesive layer after being cured by ultraviolet irradiation is preferably 6 mN / m or more higher than the surface free energy on the surface of the pressure-sensitive adhesive layer before ultraviolet irradiation, and is 7 mN / m or higher. Higher is more preferable. Further, in the pressure-sensitive adhesive tape of the present invention, the difference between the surface free energy on the surface of the pressure-sensitive adhesive layer after curing by ultraviolet irradiation and the surface free energy of the pressure-sensitive adhesive layer before ultraviolet irradiation is usually 15 mN / m or less, It is also preferable that it is 12 mN / m or less.
In the pressure-sensitive adhesive tape of the present invention, the surface free energy on the surface of the pressure-sensitive adhesive layer before ultraviolet irradiation is 25.5 mN / m or more and less than 35 mN / m, more preferably 28 to 33 mN / m.

(Contact angle for diiodomethane)
Focusing on the contact angle with diiodomethane, a large contact angle with diiodomethane on the surface of the pressure-sensitive adhesive layer means that the dispersed component is large. In this case, the intermolecular force of the polymer constituting the pressure-sensitive adhesive increases. It becomes difficult to stretch. Since the cross-linking density of the pressure-sensitive adhesive has increased significantly after UV irradiation, it becomes hard and brittle if the intermolecular force of the polymer constituting the pressure-sensitive adhesive is too strong. It tends to occur. Conversely, when the contact angle to the diiodomethane on the surface of the pressure-sensitive adhesive layer is small, the intermolecular force of the polymer constituting the pressure-sensitive adhesive is weak. Even when peeling off the protrusions, the glue does not hold the protrusions such as the bumps, and it is easy to come off. Therefore, after the pressure-sensitive adhesive layer is cured by ultraviolet irradiation, the contact angle of the pressure-sensitive adhesive layer surface with diiodomethane is preferably small to some extent.
On the other hand, when the surface protection tape is bonded to a wafer having large protrusions such as bumps or high steps on the surface, if the adhesion between the wafer and the adhesive layer is insufficient, air is involved and the wafer is bonded. Sometimes. When air is entrained, it may not be cured even when irradiated with ultraviolet rays due to inhibition of curing by oxygen in the air. In such a case, cross-linking between polymer molecules constituting the pressure-sensitive adhesive becomes insufficient, and therefore, if the intermolecular force of the polymer before ultraviolet irradiation is not high, the polymer is easily agglomerated and broken. That is, before the curing reaction by ultraviolet irradiation, it is preferable that the contact angle of the surface of the pressure-sensitive adhesive layer with diiodomethane is large to some extent.
In the pressure-sensitive adhesive tape of the present invention, the contact angle (I) with respect to diiodomethane on the surface of the pressure-sensitive adhesive layer before ultraviolet irradiation and the contact angle (II) with respect to diiodomethane on the surface of the pressure-sensitive adhesive layer after cured by ultraviolet irradiation are (I)> ( II) is satisfied, and the difference (I-II) is preferably 5 to 20 degrees.
In the pressure-sensitive adhesive tape of the present invention, the contact angle with respect to diiodomethane on the surface of the pressure-sensitive adhesive layer before ultraviolet irradiation is preferably 50 to 80 degrees, more preferably 55 to 75 degrees, and particularly preferably 55 to 66.5 degrees.

In the present invention, “ultraviolet irradiation” for curing the pressure-sensitive adhesive layer, which is performed to measure the surface free energy of the pressure-sensitive adhesive layer after curing and the contact angle with diiodomethane, is an integrated irradiation dose of 500 mJ / cm ^{2 for} ultraviolet light. The entire pressure-sensitive adhesive layer is irradiated so that For example, a high-pressure mercury lamp can be used for the ultraviolet irradiation.

The configuration of the pressure-sensitive adhesive layer in the present invention will be described first in the case where the pressure-sensitive adhesive layer has a single layer structure.
In the pressure-sensitive adhesive tape of the present invention, the pressure-sensitive adhesive layer has a composition curable by ultraviolet irradiation. The pressure-sensitive adhesive layer contains a polymer, and preferably contains a photopolymerization initiator and a crosslinking agent. The pressure-sensitive adhesive layer may contain additives or plasticizers for preventing wetting or improving slipping properties, if necessary.

(Adhesive)
The pressure-sensitive adhesive used in the pressure-sensitive adhesive layer in the pressure-sensitive adhesive tape of the present invention is not particularly limited as long as it is cured by ultraviolet irradiation, but a polymer having at least one reactive group capable of undergoing a polymerization reaction by ultraviolet irradiation (hereinafter, At least one kind of “ultraviolet curable polymer”.
The pressure-sensitive adhesive preferably contains an ultraviolet curable polymer as a main component. More specifically, the ultraviolet curable polymer is preferably contained in an amount of 50% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass or more.

The reactive group capable of undergoing a polymerization reaction upon irradiation with ultraviolet rays is preferably an ethylenically unsaturated group, that is, a group having a carbon-carbon double bond, such as a vinyl group, an allyl group, a styryl group, (Meth) acryloyloxy group, (meth) acryloylamino group, etc. are mentioned.

The ultraviolet curable polymer is not particularly limited, and examples thereof include (meth) acrylic polymer, polyester, ethylene or styrene copolymer, and polyurethane. In the present invention, these ultraviolet curable polymers may be used alone or in combination.

The pressure-sensitive adhesive layer in the present invention contains, as an essential component, a (meth) acrylic polymer having a weight average molecular weight of 10,000 to 2,000,000 as an ultraviolet curable polymer. Has a double bond, hydroxyl group and carboxy group.

In the present invention, as the (meth) acrylic polymer having a weight average molecular weight of 10,000 to 2,000,000, a commercially available product may be used, or a polymer synthesized by a conventional method may be used. When synthesizing, a (meth) acrylic polymer reacts with a polymer having a hydroxyl group and a carboxy group before the introduction of the radiation curable carbon-carbon double bond group and a compound having a radiation curable carbon-carbon double bond group. It is preferable that it is the polymer obtained by making it. In this case, it is preferable that 1 mol% to 10 mol% of (meth) acrylic acid is contained in all the monomer components forming the polymer before the introduction of the radiation curable carbon-carbon double bond group.

In the present invention, as the compound having a radiation-curable carbon-carbon double bond group, a compound obtained by reacting a hydroxyl group-containing polymer described later with a later-described 2- (meth) acryloyloxyethyl isocyanate is preferable.
In the present invention, the blending amount of 2- (meth) acryloyloxyethyl isocyanate is preferably 1 part by mass to 20 parts by mass and more preferably 6 parts by mass to 20 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer. preferable.

As a method for synthesizing the ultraviolet curable polymer, for example, (a) in the case of a polymer having an ethylenically unsaturated group, the compound having the ethylenically unsaturated group is reacted with the polymer to introduce the ethylenically unsaturated group And (b) a method using an oligomer having an ethylenically unsaturated group (for example, a urethane (meth) acryl oligomer which is a kind of a crosslinking agent) is simple and easy. Of these, the method (a) is preferred.
In the method (a), a compound having a structure having a reactive group (referred to as a reactive group α) different from the ethylenically unsaturated group is used as the compound having an ethylenically unsaturated group, and the ethylenically unsaturated group is used. As the polymer into which the group is introduced, a polymer having a structure having a reactive group β that reacts with the reactive group α of the compound having an ethylenically unsaturated group (hereinafter referred to as “polymer having a reactive group β”). Is used to react the reactive groups α and β.

For such reactive groups α and β, for example, one is preferably a group that undergoes a nucleophilic attack, and the other is a group that undergoes a nucleophilic attack or a group that undergoes an addition reaction. Examples of such reactive groups include hydroxyl groups, amino groups, mercapto groups, carboxy groups, epoxy groups, oxetanyl groups, isocyanate groups, groups forming cyclic acid anhydrides, halogen atoms, alkoxy or aryloxycarbonyls. Groups and the like.
Here, when one of the reactive groups α and β is a hydroxyl group, an amino group, a mercapto group, or a carboxy group, the other reactive group forms an epoxy group, an oxetane group, an isocyanate group, or a cyclic acid anhydride. Group, halogen atom, alkoxy or aryloxycarbonyl group.

The reactive group α of the compound having an ethylenically unsaturated group is preferably a group that undergoes a nucleophilic attack or a group that undergoes an addition reaction. For example, an epoxy group, an oxetanyl group, an isocyanate group, or a cyclic acid anhydride. A group that forms, a halogen atom, an alkoxy or aryloxycarbonyl group is preferable, an epoxy group, an oxetane group, an isocyanate group, or a group that forms a cyclic acid anhydride is more preferable, and an epoxy group, an oxetanyl group, or an isocyanate group further Preferred is an isocyanate group.

On the other hand, the reactive group β of the polymer into which the ethylenically unsaturated group is introduced is preferably a group that undergoes nucleophilic attack, for example, preferably a hydroxyl group, an amino group, a mercapto group, or a carboxy group, and a hydroxyl group, an amino group, or A mercapto group is more preferable, a hydroxyl group, an amino group, or a carboxy group is more preferable, a hydroxyl group or a carboxy group is further preferable, and a hydroxyl group is particularly preferable.

Examples of the compound having a reactive group β used for the synthesis of a compound having an ethylenically unsaturated group and a reactive group α or a polymer having a reactive group β include the following compounds.

-Compound whose reactive group is a carboxy group-
(Meth) acrylic acid, cinnamic acid, itaconic acid, fumaric acid, etc.

-Compounds whose reactive groups are hydroxyl groups-
Hydroxyalkyl (meth) acrylate having a hydroxyl group in the alcohol part [for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, trimethylolpropane mono (meth) acrylate, glycol mono (meth) acrylate, diethylene glycol Mono (meth) acrylate], N- (hydroxyalkyl) alkyl (meth) acrylamide of an alkylamine having a hydroxyl group in the amine part [for example, N-methylol (meth) acrylamide, N, N-bismethylol (meth) acrylamide], Allyl alcohol, etc.

-Compounds whose reactive groups are amino groups-
Aminoalkyl (meth) acrylate having an amino group in the alcohol part [for example, 2- (alkylamino) ethyl (meth) acrylate, 3- (alkylamino) propyl (meth) acrylate], (meth) acrylamide, etc.

-Compounds whose reactive groups are cyclic acid anhydrides-
Maleic anhydride, itaconic anhydride, fumaric anhydride, phthalic anhydride, etc.

-Compounds whose reactive groups are epoxy groups or oxetanyl groups-
Glycidyl (meth) acrylate, allyl glycidyl ether, 3-ethyl-3-hydroxymethyloxetane, etc.

-Compounds whose reactive groups are isocyanate groups-
(Meth) acryloyloxyalkyl isocyanate [for example, 2- (meth) acryloyloxyethyl isocyanate, 2- (meth) acryloyloxypropyl isocyanate], a part of the isocyanate group of a polyvalent isocyanate compound, a hydroxyl group or a carboxy group, and ethylene Urethanes with compounds having functional unsaturated groups (for example, 2- to 10-functional (meth) acrylic urethane acrylate oligomers), etc.

Examples of the urethane acrylate oligomer include hydroxyalkyl (meth) having a hydroxyl group in an alcohol part such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, pentaerythritol tri (meth) acrylate, and the like. Isocyanates obtained by reacting acrylates with diisocyanates such as toluene diisocyanate, methylene bisphenyl diisocyanate, hexamethylene diisocyanate, naphthalene diisocyanate, methylene biscyclohexyl isocyanate, isophorone diisocyanate or trifunctional or higher isocyanates Oligomers having at least one group are preferred. Moreover, in addition to a hydroxyalkyl (meth) acrylate and a polyvalent isocyanate, an oligomer obtained by reacting a polyol compound, a polyether diol compound or a polyester diol compound may be used.

-Compounds whose reactive group is a halogen atom-
Halogenated triazines such as 2,4,6-trichloro-1,3,5-triazine, 2,4-dichloro-6-methoxy-1,3,5-triazine, etc.

The compound having the ethylenically unsaturated group and the reactive group α is preferably a compound in which the reactive group is an isocyanate group, while the monomer used for the synthesis of the polymer having the reactive group β is the above-described monomer. A compound in which the reactive group is a carboxy group or a compound in which the reactive group is a hydroxyl group is preferred, and a compound in which the reactive group is a hydroxyl group is more preferred.

The method (b) uses the urethane (meth) acrylate oligomer (the oligomer is also a kind of crosslinking agent as described later), and a (meth) acrylic copolymer and a urethane (meth) acrylate oligomer. Can coexist with the UV curable pressure-sensitive adhesive layer. The (meth) acrylic copolymer is preferably obtained by polymerizing (meth) acrylic acid and (meth) acrylic acid ester. The preferable form of the (meth) acrylic acid ester component constituting the (meth) acrylic copolymer is the same as that described as the copolymerizing component in the polymer having the reactive group β described later.

The ratio of the monomer component having the reactive group β to the total monomer component constituting the polymer having the reactive group β is preferably 5 to 50 mol%, and more preferably 20 to 40 mol%.

In addition, when a compound having an ethylenically unsaturated group and a reactive group α is reacted with a polymer having a reactive group β to introduce an ethylenically unsaturated group into the polymer having a reactive group β, The compound having a reactive group α is preferably reacted in an amount of 1 to 40 parts by mass, more preferably 1 to 30 parts by mass, with respect to 100 parts by mass of the polymer having a reactive group β. It is more preferable to carry out a partial reaction, and it is particularly preferred to carry out a reaction of 1 to 10 parts by mass.
By leaving the unreacted reactive group β after the reaction of the reactive groups α and β, the resin characteristics can be adjusted with a crosslinking agent or the like described later.

The polymer having the reactive group β preferably has a (meth) acrylic acid ester component as a copolymer component together with the monomer component having the reactive group β as a constituent component.
As the (meth) acrylic acid ester, one or more alkyl (meth) acrylates are preferable. The alcohol part of the (meth) acrylic acid ester does not have the reactive group β. Preferably, the alcohol part of the (meth) acrylic acid ester is unsubstituted.
In such (meth) acrylic acid ester, the alcohol part preferably has 1 to 12 carbon atoms. The number of carbon atoms in the alcohol part is more preferably 1 to 10, more preferably 4 to 10, and the alcohol part is preferably a branched alkyl group, and 2-ethylhexyl (meth) acrylate is particularly preferable.

In addition, when the UV-polymerizable polymer contains a plurality of (meth) acrylic acid ester components as constituent components, the (meth) acrylic acid ester component contains (meth) acrylic having 1 to 8 carbon atoms in the alcohol part. It is preferable that an acid ester component is contained, and among them, an ethyl (meth) acrylate component is preferably contained.

Hereinafter, specific examples of the monomer incorporated in the polymer as the copolymerization component will be given.

-(Meth) acrylic acid alkyl ester-
As the alkyl ester of (meth) acrylic acid, those having 1 to 12 carbon atoms in the alcohol part are preferable. For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth) Butyl acrylate, isobutyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, (meth ) Isodecyl acrylate and the like. These may be used singly or in combination of two or more. By using two or more types in combination, various functions as the pressure-sensitive adhesive can be exhibited, and furthermore, it is possible to achieve both the followability to the step on the surface of the semiconductor wafer and the non-contamination property including prevention of adhesive residue.

-Monomers other than alkyl esters of (meth) acrylic acid-
Examples of monomers other than (meth) acrylic acid alkyl esters include vinyl acetate, styrene, and (meth) acrylic acid amides such as N, N-diethylacrylic acid amide, N, N-diethylacrylic acid amide, and N-isopropylacrylic acid. And acid amides and N-acryloylmorpholine. These may be used singly or in combination of two or more.

The ratio of the copolymerization component to the total monomer components constituting the polymer having the reactive group β is preferably 5 to 50 mol%, more preferably 20 to 40 mol%.

In the present invention, the surface free energy and the contact angle of the pressure-sensitive adhesive layer surface with diiodomethane or water can be freely controlled by adjusting the type and content of the ultraviolet curable polymer and the polymer used in combination with the polymer.
Among them, control by adjusting the monomer component having a reactive group β constituting the ultraviolet curable polymer, a copolymer component such as an alkyl (meth) acrylate component, a (meth) acrylic acid component, and the content ratio is preferable. .

For example, when the reactive group β of the polymer having the reactive group β is a hydroxyl group, a carboxy group, or an amino group (an amide-containing group), the reactive group β includes a reactive group α and an ethylenically unsaturated group. Although it reacts with the compound it has, unreacted hydroxyl groups, carboxy groups, or amino groups can remain. In addition, there are two types of reactive groups β (for example, a carboxy group and a hydroxyl group) in a polymer having a reactive group β, and only one of them (for example, only a part of a hydroxyl group) is a reactive group. By reacting with α, a part of one reactive group (hydroxyl group) and the other reactive group (carboxyl group) can be left, and depending on the type and amount of the remaining reactive group, surface free energy and adhesion The contact angle of the agent layer surface with water can be controlled.

In this case, for example, the carboxy group has a higher polarity than the hydroxyl group and amino group, and the surface free energy and the contact angle change greatly.
Further, for example, the cohesive force is improved by pseudo-crosslinking including association by hydrogen bonding between carboxy groups and amino groups (amide-containing groups), so that the contact angle with diiodomethane can also be adjusted.
On the contrary, when the remaining reactive group β is mainly a hydroxyl group, the polarity is not as high as that of the carboxy group. Therefore, although the influence on the surface free energy of the pressure-sensitive adhesive layer surface and the contact angle to water of the pressure-sensitive adhesive layer surface is small, The surface free energy can be adjusted with little influence on the contact angle with diiodomethane because the pseudo-crosslinking due to is hardly formed.

The amount of the reactive group β remaining in the ultraviolet curable polymer depends on the compounding amount of the compound having the reactive group α, but can also be adjusted by the type and the compounding amount of the crosslinking agent described later. That is, the surface free energy of the pressure-sensitive adhesive layer surface can be adjusted by the crosslinking agent.
In the present invention, the crosslinking agent is preferably added in an amount of 0.1 to 5 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer.

In the pressure-sensitive adhesive tape of the present invention, in order to control the polar component of the surface free energy of the pressure-sensitive adhesive layer, the ultraviolet curable polymer contained in the pressure-sensitive adhesive layer is a hydroxyl group, a hydroxyl group and a carboxy group, or a hydroxyl group and an amino group (amide-containing amide). Group). Especially, it is preferable to contain a hydroxyl group and a carboxy group.
The hydroxyl value of the polymer constituting the pressure-sensitive adhesive layer surface is preferably 5 to 100 mgKOH / g, more preferably 10 to 100 mgKOH / g, still more preferably 20 to 100 mgKOH / g, and particularly preferably 30 to 100 mgKOH / g. By setting it within this range, it becomes possible to control the cohesive force by the crosslinking agent and the surface free energy by the residual hydroxyl group not involved in crosslinking. The acid value of the polymer constituting the surface of the pressure-sensitive adhesive layer is preferably 0 to 70 mgKOH / g, more preferably 5 to 65 mgKOH / g, further preferably 10 to 65 mgKOH / g or 5 to 35 mgKOH / g, and more preferably 10 to 35 mgKOH / g. / G is particularly preferred, and 15 to 35 mg KOH / g is most preferred. Among them, the hydroxyl value of the polymer constituting the surface of the pressure-sensitive adhesive layer is preferably 10 to 100 mgKOH / g, the acid value is preferably 5 to 65 mgKOH / g, the hydroxyl value of the polymer is 20 to 100 mgKOH / g, and the acid value is 10 to 10 mg. 65 mgKOH is more preferable, the hydroxyl value of the polymer is 30 to 100 mgKOH / g, the acid value is more preferably 10 to 35 mgKOH, the hydroxyl value of the polymer is 30 to 100 mgKOH / g, and the acid value is particularly preferably 15 to 35 mgKOH. In the present invention, when the hydroxyl value of the polymer is 30 to 100 mgKOH / g, the acid value of the polymer is preferably 5 to 65 mgKOH / g (preferably 5 to 35 mgKOH / g). Moreover, the carboxy group is preferable as the acid group mainly contained in the polymer constituting the pressure-sensitive adhesive layer surface.

The acid value is measured in accordance with JIS K5601-2-1: 1999 using a polymer before ultraviolet irradiation (before curing) as a sample. The hydroxyl value is measured according to JIS K 0070.
In the present specification, the “hydroxyl value” is a hydroxyl value of solid content of a polymer before ultraviolet irradiation (before curing), that is, a hydroxyl value obtained by KOH of a hydroxyl group necessary for acylation. The acid value of the solid content of the polymer before ultraviolet irradiation (before curing), that is, the acid value determined with KOH, which is an alkali necessary for neutralizing acidic groups such as carboxy groups.

The weight average molecular weight of the ultraviolet curable polymer used in the pressure-sensitive adhesive layer is 10,000 to 2,000,000, preferably 50,000 to 2,000,000. When the polymer and another polymer are used in combination, the weight average molecular weight of the polymer used in combination is also It is preferable to be within the range.
When the weight average molecular weight of the polymer used for the pressure-sensitive adhesive layer is too large, polymerization is difficult and the degree of dispersion becomes high, and a low molecular weight polymer is contained, so that the cohesive force may be lowered. On the other hand, if the molecular weight is too small, the cohesive force of the polymer itself is lowered, and this tends to cause adhesive residue. In the pressure-sensitive adhesive tape of the present invention, the polymer used for the pressure-sensitive adhesive layer preferably has a weight average molecular weight of 200,000 to 800,000.
The weight average molecular weight is a value obtained by dissolving a 1% solution obtained by dissolving in tetrahydrofuran by gel permeation chromatography (trade name: 150-C ALC / GPC, manufactured by Waters Co., Ltd.) as a weight average molecular weight in terms of polystyrene. It is calculated.

(Photopolymerization initiator)
The pressure-sensitive adhesive layer of the present invention particularly preferably contains a photopolymerization initiator. The adhesive force after crosslinking can be controlled by adjusting the blending amount of the photopolymerization initiator in the adhesive layer. Specific examples of such a photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl diphenyl sulfide, tetramethyl thiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, β-chloranthraquinone and the like can be mentioned. The photopolymerization initiator is usually used at a ratio of 0.1 to 10 parts by mass with respect to 100 parts by mass of the total amount of the polymer having an ethylenically unsaturated group and the compound having an ethylenically unsaturated group. By irradiating the ultraviolet curable pressure-sensitive adhesive layer thus formed with ultraviolet rays, the adhesive force can be greatly reduced, and the pressure-sensitive adhesive tape can be easily peeled off from the adherend.

(Crosslinking agent)
In this invention, it is preferable to contain a crosslinking agent in an adhesive layer. The reactive group that is the crosslinkable group of the crosslinker is preferably a crosslinker that reacts with the reactive group β of the polymer having the reactive group β.
For example, when the reactive group β of the resin having the reactive group β is a carboxy group or a hydroxyl group, the reactive group that is a crosslinking group of the crosslinking agent is a cyclic acid anhydride, an isocyanate group, an epoxy group, or a halogen atom. It is preferable that it is an isocyanate group or an epoxy group.

By using such a crosslinking agent, the residual amount of the reactive group β of the polymer having the reactive group β can be adjusted depending on the blending amount, and the surface free energy can be controlled within a desired range.
Moreover, the cohesive force of an adhesive layer can also be controlled by using a crosslinking agent.

Examples of the crosslinking agent preferably used for the pressure-sensitive adhesive layer include polyvalent isocyanate compounds, polyvalent epoxy compounds, polyvalent aziridine compounds, chelate compounds and the like. Specific examples of the polyvalent isocyanate compound include toluylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and adduct types thereof.

Examples of the polyvalent epoxy compound include ethylene glycol diglycidyl ether and terephthalic acid diglycidyl ester acrylate. Polyvalent aziridine compounds include tris-2,4,6- (1-aziridinyl) -1,3,5-triazine, tris [1- (2-methyl) -aziridinyl] phosphine oxide, hexa [1- (2- Methyl) -aziridinyl] triphosphatriazine and the like. Examples of the chelate compound include ethyl acetoacetate aluminum diisopropylate and aluminum tris (ethyl acetoacetate).

Further, the pressure-sensitive adhesive used in the present invention uses a crosslinking agent having at least two ethylenically unsaturated groups in the molecule, preferably an oligomer or polymer crosslinking agent, and the crosslinking agent itself is used as an ultraviolet curable resin. May be.

Examples of low molecular weight compounds having at least two ethylenically unsaturated groups in the molecule include trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, and dipentaerythritol monohydroxypentaacrylate. And dipentaerythritol hexaacrylate, 1,4-butylene glycol diacrylate, 1,6 hexanediol diacrylate, polyethylene glycol diacrylate, oligoester acrylate, and the like.

In addition, urethane acrylate oligomers can also be used. Specifically, 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, etc. A (meth) acrylate having a hydroxy group (for example, a terminal isocyanate urethane prepolymer obtained by reacting diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane 4,4-diisocyanate, etc.) , 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, polyethylene glycol (meth) acrylate] can be widely applied.

The content of the crosslinking agent is preferably 0.1 to 5.0 parts by mass, more preferably 0.5 to 4.0 parts by mass with respect to 100 parts by mass of the polymer constituting the pressure-sensitive adhesive layer.

(Additive)
In this invention, the adhesive layer may contain the additive other than the above.
Examples of such additives include silicone acrylates (for example, silicone diacrylate and silicone hexaacrylate) and ultraviolet curing accelerators as additives for preventing wetting or improving slip properties. Moreover, you may contain the aminoacrylate as a water-resistant agent as the said additive. Further, a plasticizer may be included as the additive. Moreover, the surfactant used in the case of superposition | polymerization of a polymer may be included.

(Storage modulus)
The storage elastic modulus of the pressure-sensitive adhesive or pressure-sensitive adhesive layer of the present invention is not particularly limited, but considering the followability to the adhesive residue and uneven shape, the storage elastic modulus before ultraviolet irradiation is preferably 30000-75000 Pa, More preferably, it is 35000 to 60000 Pa. The storage elastic modulus of the pressure-sensitive adhesive after curing by ultraviolet irradiation (after curing the whole pressure-sensitive adhesive layer so that the total irradiation amount is 500 mJ / cm ² ) is preferably 100,000 Pa or more.

In the pressure-sensitive adhesive tape of the present invention, the pressure-sensitive adhesive layer may have a multilayer structure in which two or more pressure-sensitive adhesives having different compositions are laminated as described above. In the case where the pressure-sensitive adhesive layer has a multilayer structure, the configuration of the layer constituting at least the surface of the pressure-sensitive adhesive layer has been described as the configuration of the above-mentioned pressure-sensitive adhesive layer (that is, the configuration of the pressure-sensitive adhesive layer having a single-layer structure) ). Moreover, it is preferable that all the adhesive layers of a multilayer structure are the structures of the above-mentioned adhesive layer (namely, the aspect demonstrated as a structure of the adhesive layer of a single layer structure).

(Adhesive layer thickness)
The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably 10 to 300 μm, more preferably 30 to 200 μm, and further preferably 40 to 200 μm.
Moreover, you may provide an adhesive layer on both surfaces of a base film according to the objective.
In order to form the pressure-sensitive adhesive layer on the base film, at least one type of pressure-sensitive adhesive can be applied to at least one surface of the base film by a conventional method as described above.

(Other layers)
In this invention, you may provide intermediate | middle layers, such as a primer layer, as needed between a base film and an adhesive layer.

<Release liner>
The pressure-sensitive adhesive tape of the present invention may have a release liner on the pressure-sensitive adhesive layer. As the release liner, a polyethylene terephthalate film subjected to silicone release treatment or the like is used. If necessary, a polypropylene film that is not subjected to silicone release treatment may be used.

<Base film>
The material of the base film used in the present invention is mainly intended to protect against impact when grinding the back surface of a semiconductor wafer, and is particularly resistant to water washing and the like and retainability of processed parts. It is important to have Examples of such a base film include those described in JP-A No. 2004-186429.
As the base film used in the present invention, those usually used for an adhesive tape can be used. For example, polyethylene, polypropylene, ethylene-propylene copolymer, polybutene, ethylene-vinyl acetate copolymer, Homopolymers or copolymers of α-olefins such as ethylene-acrylic acid ester copolymers and ionomers, engineering plastics such as polyethylene terephthalate, polycarbonate and polymethyl methacrylate, polyurethane, styrene-ethylene-butene or pentene copolymer Examples thereof include thermoplastic elastomers such as coalesced ones, which may be a mixture of two or more selected from these groups, or a multilayered one.

Among these, in the present invention, an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid ester copolymer, and a copolymer of a urethane acrylate oligomer and isobornyl acrylate are preferable. In addition, the copolymer of a urethane acrylate oligomer and isobornyl acrylate can manufacture a urethane acrylate oligomer and isobornyl acrylate with a photoinitiator as demonstrated in the adhesive layer.

The base film is preferably visible light transmissive, and more preferably UV transmissive. The thickness of the base film is not particularly limited, but is preferably 50 to 500 μm. When the thickness of the substrate film is 50 μm or less, the thickness accuracy is liable to be deteriorated during the production, and the rigidity is low, so that the wafer holding ability is insufficient, and a conveyance error may occur. On the other hand, if the thickness of the base film exceeds 500 μm, warpage after grinding becomes large, which may cause a conveyance error or may not be taped because the rigidity is too strong. The thickness of the base film is more preferably 80 to 300 μm, and further preferably 100 to 300 μm.

Further, the base film may be a film obtained by UV curing an adhesive. For example, those produced by a method such as JP-A-11-343469 can be used.

<< Semiconductor wafer and processing method of semiconductor wafer >>
There is no restriction | limiting in particular in the semiconductor wafer which applies the adhesive tape of this invention, It can apply to the semiconductor wafer of all forms.
A semiconductor wafer processing method using the adhesive tape of the present invention (hereinafter referred to as “the processing method of the present invention”) includes at least the following steps (A) to (D).

(A) The process of bonding the adhesive tape of this invention on the surface of a semiconductor wafer (B) The process of grinding the surface (back surface of a wafer) on the opposite side to the bonding surface of the adhesive tape of this invention of the said semiconductor wafer. (C) Step of irradiating the pressure-sensitive adhesive tape of the present invention with radiation to cure the pressure-sensitive adhesive tape of the present invention (D) Step of peeling the pressure-sensitive adhesive tape of the present invention from the semiconductor wafer;
The radiation irradiated in the step (C) refers to light rays such as ultraviolet rays or ionizing radiations such as electron beams. It is preferable that the radiation irradiated at the said process (C) is an ultraviolet-ray. The cumulative radiation dose in the step (C) is preferably about 300 to 1000 mJ / cm ² .

The pressure-sensitive adhesive tape of the present invention is also suitable as a surface protection tape for a semiconductor wafer having an insulating layer on the bonding surface of the pressure-sensitive adhesive tape. That is, even if an insulating layer containing a polyimide resin or the like is present on the surface of the semiconductor wafer, both good adhesion and good peelability can be achieved.
Moreover, even if it has bumps, such as an electrode, on the bonding surface of an adhesive tape, it can make favorable adhesiveness and favorable peelability compatible. For example, even when the height of bumps such as electrodes is 15 μm or more, and even 50 μm or more, both good adhesion and good peelability can be achieved. The height of the bump is practically 300 μm or less.
Further, the thickness of the thin film semiconductor wafer ground by the processing method of the present invention is preferably 20 to 500 μm, and more preferably 50 to 200 μm.
By using the processing method of the present invention, a thin film semiconductor wafer can be obtained with a high yield. That is, the semiconductor wafer processing method of the present invention is suitable as a method for manufacturing a thin film semiconductor wafer.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1
50 parts by mass of urethane acrylate oligomer having a weight average molecular weight of 3500 (manufactured by Shin-Nakamura Chemical Co., Ltd.), 50 parts by mass of isobornyl acrylate, and 5.0 parts by mass of Irgacure 184 (manufactured by BASF) as a photopolymerization initiator. An ultraviolet curable resin composition was obtained by blending. The obtained ultraviolet curable resin composition was coated on a PET film (Toray Industries, Inc .: thickness 38 μm) as a process sheet for casting by a fountain die method so as to have a thickness of 270 μm. A layer was formed. Immediately after coating, the same PET film is further laminated on the resin composition layer, and then UV irradiation is performed using a high-pressure mercury lamp (160 W / cm, height 10 cm) under the condition of a light amount of 500 mJ / cm ^2. Thus, the resin composition layer was crosslinked and cured to obtain a base film having a thickness of 270 μm.

A polymer solution was obtained by blending 1.5 mol% of methacrylic acid, 64 mol% of 2-ethylhexyl acrylate and 34.5 mol% of 2-hydroxyethyl acrylate, and polymerizing in solution. 2-Methacryloyloxyethyl isocyanate is mixed in 18 parts by mass (Showa Denko Co., Ltd., Karenz MOI) solution with respect to 100 parts by mass of this polymer, and ethylenically unsaturated groups are introduced into hydroxy groups. A group-containing acrylic copolymer polymer (weight average molecular weight: 400,000, hydroxyl value 99.1 mgKOH / g, acid value 10.5 mgKOH / g) was synthesized.
In this ethylenically unsaturated group-containing acrylic copolymer polymer, 2.5 parts by mass of Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent and 5.0 parts by mass of Irgacure 184 (manufactured by BASF) as a photopolymerization initiator. Partially blended to obtain a pressure-sensitive adhesive composition.
The pressure-sensitive adhesive composition was applied to the base film from which the PET film laminated on both sides was peeled off so that the thickness of the pressure-sensitive adhesive was 40 μm, and bonded to a transparent release liner (thickness 50 μm). A 310 μm adhesive tape was obtained.

<Example 2>
A polymer solution was obtained by blending 2.0 mol% of methacrylic acid, 70 mol% of 2-ethylhexyl acrylate, and 28 mol% of 2-hydroxyethyl acrylate, and polymerizing in solution. Ethylenically unsaturated by introducing 10 parts by mass of 2-methacryloyloxyethyl isocyanate in 100 parts by mass of this polymer (Showen Denko Co., Ltd., Karenz MOI) solution and introducing ethylenically unsaturated groups into hydroxy groups. A group-containing acrylic copolymer polymer (weight average molecular weight: 500,000, hydroxyl value: 50.8 mgKOH / g, acid value: 10.5 mgKOH / g) was synthesized.
In this ethylenically unsaturated group-containing acrylic copolymer polymer, 0.5 parts by mass of Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent and 5.0 parts by mass of Irgacure 184 (manufactured by BASF) as a photopolymerization initiator. Partially blended to obtain a pressure-sensitive adhesive composition.
The obtained pressure-sensitive adhesive composition was coated on a transparent release liner (thickness 50 μm) so that the thickness of the pressure-sensitive adhesive was 130 μm, and was bonded to an ethylene vinyl acetate (EVA) film having a thickness of 100 μm. A 230 μm adhesive tape was obtained.

<Example 3>
A polymer solution was obtained by blending 4.0 mol% of methacrylic acid, 76 mol% of 2-ethylhexyl acrylate, and 20 mol% of 2-hydroxyethyl acrylate, and polymerizing in solution. 2-acryloyloxyethyl isocyanate is mixed in 10 parts by mass (Showa Denko Co., Ltd., Karenz AOI) solution with respect to 100 parts by mass of this polymer, and ethylenically unsaturated groups are introduced into the hydroxy groups. An acrylic copolymer polymer containing a saturated group (weight average molecular weight: 350,000, hydroxyl value: 33.8 mgKOH / g, acid value: 19.9 mgKOH / g) was synthesized.
As a crosslinking agent, 1.5 parts by mass of Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.) and 0.3 parts by mass of TETRAD-X (manufactured by Mitsubishi Gas Chemical Co., Ltd.) are used as a crosslinking agent for the ethylenically unsaturated group-containing acrylic copolymer polymer. As a photopolymerization initiator, 5.0 parts by mass of Irgacure 651 (manufactured by BASF) was blended to obtain a pressure-sensitive adhesive composition.
The obtained pressure-sensitive adhesive composition was applied onto a transparent release liner so that the thickness of the pressure-sensitive adhesive was 130 μm, and the formed pressure-sensitive adhesive layer was bonded to a low-density polyethylene (LDPE) film having a thickness of 100 μm. An adhesive tape having a thickness of 230 μm was obtained.

<Example 4>
A polymer solution was obtained by blending 6.0 mol% of methacrylic acid, 74 mol% of ethyl acrylate, and 20 mol% of 2-hydroxyethyl acrylate, and polymerizing in solution. Ethylenically unsaturated by introducing 10 parts by mass of 2-methacryloyloxyethyl isocyanate in 100 parts by mass of this polymer (Showen Denko Co., Ltd., Karenz MOI) solution and introducing ethylenically unsaturated groups into hydroxy groups. A group-containing acrylic copolymer polymer (weight average molecular weight: 700,000, hydroxyl value: 33.7 mgKOH / g, acid value: 33.1 mgKOH / g) was synthesized.
In this ethylenically unsaturated group-containing acrylic copolymer polymer, 0.9 part by mass of Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent, and 5.0 of Esacure KIP-150 (manufactured by Lamberte) as a photopolymerization initiator. An adhesive composition was obtained by blending parts by mass.
The obtained pressure-sensitive adhesive composition was coated on a transparent release liner (thickness 50 μm) so that the thickness of the pressure-sensitive adhesive was 130 μm, and bonded to a 100 μm-thick EVA film, and a 230 μm-thick pressure-sensitive adhesive tape was attached. Obtained.

<Example 5>
A polymer solution was obtained by mixing 1.0 mol% of methacrylic acid, 78 mol% of 2-ethylhexyl acrylate, and 21 mol% of 2-hydroxyethyl acrylate, and polymerizing in solution. Ethylenically unsaturated by introducing 10 parts by mass of 2-methacryloyloxyethyl isocyanate in 100 parts by mass of this polymer (Showen Denko Co., Ltd., Karenz MOI) solution and introducing ethylenically unsaturated groups into hydroxy groups. A group-containing acrylic copolymer polymer (weight average molecular weight: 750,000, hydroxyl value: 33.7 mgKOH / g, acid value: 5.6 mgKOH / g) was synthesized.
To this ethylenically unsaturated group-containing acrylic copolymer polymer, 2.0 parts by mass of Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent and 5.0 of Esacure KIP-150 (manufactured by Lamberte) as a photopolymerization initiator are used. An adhesive composition was obtained by blending parts by mass.
The obtained pressure-sensitive adhesive composition was coated on a transparent release liner (thickness 50 μm) so that the thickness of the pressure-sensitive adhesive was 150 μm, and bonded to a polypropylene (PP) film having a thickness of 80 μm. An adhesive tape was obtained.

<Example 6>
A polymer solution was obtained by mixing 1.0 mol% of methacrylic acid, 78 mol% of 2-ethylhexyl acrylate, and 21 mol% of 2-hydroxyethyl acrylate, and polymerizing in solution. 2-Methacryloyloxyethyl isocyanate is mixed in 6 parts by mass (Showa Denko Co., Ltd., Karenz MOI) solution with 100 parts by mass of this polymer, and ethylenically unsaturated groups are introduced into the hydroxy groups. A group-containing acrylic copolymer polymer (weight average molecular weight: 600,000, hydroxyl value: 55.6 mgKOH / g, acid value: 5.9 mgKOH / g) was synthesized.
To this ethylenically unsaturated group-containing acrylic copolymer polymer, 0.5 parts by mass of Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent, and 5.0 of Esacure KIP-150 (manufactured by Lamberte) as a photopolymerization initiator are used. An adhesive composition was obtained by blending parts by mass.
The obtained pressure-sensitive adhesive composition was coated on a transparent release liner (thickness 50 μm) so that the thickness of the pressure-sensitive adhesive was 150 μm, and bonded to an EVA film having a thickness of 150 μm, and a pressure-sensitive adhesive tape having a thickness of 300 μm was attached. Obtained.

<Comparative Example 1>
A polymer solution having a weight average molecular weight of 700,000 was obtained by blending 78 mol% of 2-ethylhexyl acrylate, 21 mol% of 2-hydroxyethyl acrylate, and 1 mol% of methacrylic acid, followed by polymerization in the solution. Ethylenically unsaturated by introducing 10 parts by mass of 2-methacryloyloxyethyl isocyanate in 100 parts by mass of this polymer (Showen Denko Co., Ltd., Karenz MOI) solution and introducing ethylenically unsaturated groups into hydroxy groups. A group-containing acrylic copolymer polymer (weight average molecular weight: 600,000, hydroxyl value: 50.1 mgKOH / g, acid value: 6.1 mgKOH / g) was synthesized.
In this ethylenically unsaturated group-containing acrylic copolymer polymer, 1.5 parts by mass of Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent and 3.0 parts by mass of Irgacure 184 (manufactured by BASF) as a photopolymerization initiator As an additive, 0.3 part by mass of Ebecryl 350 (manufactured by Daicel Ornex Co., Ltd.) was blended to obtain an adhesive composition.
The obtained pressure-sensitive adhesive composition was coated on a transparent release liner so that the thickness of the pressure-sensitive adhesive became 130 μm, and the formed pressure-sensitive adhesive layer was bonded to an EVA film having a thickness of 100 μm, and a pressure-sensitive adhesive having a thickness of 230 μm. I got a tape.

<Comparative example 2>
20 mol% of methacrylic acid, 30 mol% of 2-ethylhexyl acrylate, 10 mol% of 2-hydroxyethyl acrylate, and 40 mol% of methyl acrylate were blended and polymerized in the solution to obtain a polymer solution having a weight average molecular weight of 600,000. The polymer had a hydroxyl value of 28.1 mgKOH / g and an acid value of 60.8 mgKOH / g.
To 100 parts by mass of the polymer in the polymer solution, 100 parts by mass of a hexafunctional urethane acrylate oligomer (made by Shin-Nakamura Chemical Co., Ltd.) as a UV-reactive resin and a trifunctional urethane acrylate oligomer (Shin Nakamura Chemical Co., Ltd.) 50 parts by mass), 4.0 parts by mass of Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent, 10 parts by mass of Irgacure 184 (manufactured by BASF) as a photopolymerization initiator, and Ebecryl 350 as an additive 0.5 parts by mass (manufactured by Daicel Ornex Co., Ltd.) was blended to obtain an adhesive composition.
The obtained pressure-sensitive adhesive composition was applied onto a transparent release liner so that the thickness of the pressure-sensitive adhesive was 130 μm, and the formed pressure-sensitive adhesive layer was bonded to a 100 μm-thick LDPE (low density polyethylene) film, An adhesive tape having a thickness of 230 μm was obtained.

<Comparative Example 3>
20 mol% of methacrylic acid, 30 mol% of 2-ethylhexyl acrylate, 10 mol% of 2-hydroxyethyl acrylate, and 40 mol% of methyl acrylate were blended and polymerized in the solution to obtain a polymer solution having a weight average molecular weight of 600,000. The polymer had a hydroxyl value of 33.5 mgKOH / g and an acid value of 48.6 mgKOH / g.
To 100 parts by mass of the polymer in the polymer solution, 100 parts by mass of a pentafunctional urethane acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd.) as a UV-reactive resin and trifunctional urethane acrylate oligomer (Shin Nakamura Chemical Co., Ltd.) 10 parts by mass) and 30 parts by mass of a bifunctional urethane acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd.) and 4.0 parts by mass of Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a cross-linking agent. 5 parts by mass of Irgacure 184 (manufactured by BASF) as an initiator and 0.5 part by mass of Ebecryl 350 (manufactured by Daicel Ornex Co., Ltd.) as an additive were blended to obtain a pressure-sensitive adhesive composition.
The obtained pressure-sensitive adhesive composition was applied onto a transparent release liner so that the thickness of the pressure-sensitive adhesive was 130 μm, and the formed pressure-sensitive adhesive layer was bonded to an LDPE film having a thickness of 100 μm, and a pressure-sensitive adhesive having a thickness of 230 μm. I got a tape.

<Comparative example 4>
20 mol% of methacrylic acid, 35 mol% of 2-ethylhexyl acrylate, 5 mol% of 2-hydroxyethyl acrylate, and 40 mol% of methyl acrylate were blended and polymerized in the solution to obtain a polymer solution having a weight average molecular weight of 200,000. The polymer had a hydroxyl value of 5.5 mgKOH / g and an acid value of 60.8 mgKOH / g.
80 parts by mass of a hexafunctional urethane acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd.) and a bifunctional urethane acrylate oligomer (Shin Nakamura Chemical Co., Ltd.) as an ultraviolet-reactive resin with respect to 100 parts by mass of the polymer in the polymer solution. 20 parts by mass), 4.0 parts by mass of Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent, 2.5 parts by mass of Irgacure 184 (manufactured by BASF) as a photopolymerization initiator, and additives 0.5 parts by mass of Ebecryl 350 (manufactured by Daicel Ornex Co., Ltd.) was blended to obtain an adhesive composition.
The obtained pressure-sensitive adhesive composition was coated on a transparent release liner so that the thickness of the pressure-sensitive adhesive was 150 μm, and the formed pressure-sensitive adhesive layer was bonded to an LDPE film having a thickness of 100 μm, and a pressure-sensitive adhesive having a thickness of 250 μm. I got a tape.

<Comparative Example 5>
20 mol% of methacrylic acid, 60 mol% of 2-ethylhexyl acrylate and 20 mol% of methyl acrylate were blended and polymerized in the solution to obtain a polymer solution having a weight average molecular weight of 400,000. The polymer had a hydroxyl value of 0 mgKOH / g and an acid value of 48.8 mgKOH / g.
The polymer solution contains 1.0 part by mass of Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.) and 1.0 part by mass of TETRAD-X (manufactured by Mitsubishi Gas Chemical Co., Ltd.) as crosslinks with respect to 100 parts by mass of the polymer. A pressure-sensitive adhesive composition was obtained.
The obtained pressure-sensitive adhesive composition was applied onto a transparent release liner so that the thickness of the pressure-sensitive adhesive was 130 μm, and the formed pressure-sensitive adhesive layer was bonded to an LDPE film having a thickness of 100 μm, and a pressure-sensitive adhesive having a thickness of 230 μm. I got a tape.

<Comparative Example 6>
A polymer solution having a weight average molecular weight of 700,000 was obtained by blending 78 mol% of 2-ethylhexyl acrylate, 21 mol% of 2-hydroxyethyl acrylate, and 1 mol% of methacrylic acid, followed by polymerization in the solution. By mixing 2-methacryloyloxyethyl isocyanate in 5.0 parts by mass (Showa Denko KK, Karenz MOI) solution with respect to 100 parts by mass of this polymer and introducing ethylenically unsaturated groups into hydroxy groups, An acrylic copolymer polymer containing an unsaturated group (weight average molecular weight: 700,000, hydroxyl value: 38.0 mgKOH / g, acid value: 6.5 mgKOH / g) was synthesized.
As a crosslinking agent, 1.0 part by mass of Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.) and 0.5 part by mass of TETRAD-X (manufactured by Mitsubishi Gas Chemical Co., Ltd.) are used as a crosslinking agent for the ethylenically unsaturated group-containing acrylic copolymer polymer. In addition, 5.0 parts by mass of Irgacure 184 (manufactured by BASF) as a photopolymerization initiator was blended to obtain a pressure-sensitive adhesive composition.
The obtained pressure-sensitive adhesive composition was coated on a transparent release liner so that the thickness of the pressure-sensitive adhesive became 130 μm, and the formed pressure-sensitive adhesive layer was bonded to an EVA film having a thickness of 100 μm, and a pressure-sensitive adhesive having a thickness of 230 μm. I got a tape.

<Comparative Example 7>
95 parts by mass of 2-ethylhexyl acrylate, 5 parts by mass of 2-hydroxyethyl acrylate, 0.2 parts by mass of Irgacure 651 (manufactured by BASF, 50% ethyl acetate solution) as a photo radical generator, and 0.01 parts by mass of lauryl mercaptan Was dissolved in ethyl acetate to obtain a solution. Polymerization was performed by irradiating this solution with ultraviolet rays to obtain an ethyl acetate solution of the polymer. Further, 3.5 parts by mass of 2-methacryloyloxyethyl isocyanate (manufactured by Showa Denko KK, Karenz MOI) was reacted with 100 parts by mass of the solid content of this solution, the weight average molecular weight was 700,000, An acrylic copolymer which was a crosslinked (meth) acrylic resin containing an ethylenically unsaturated group having a value of 11.1 mgKOH / g and an acid value of 0.9 mgKOH / g was synthesized.
1.0 parts by mass of Irgacure 184 (manufactured by BASF) as a photopolymerization initiator and U-324A as a urethane acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd.) 2 0.0 parts by mass was blended to obtain an adhesive composition.
The obtained pressure-sensitive adhesive composition was coated on a transparent release liner so that the thickness of the pressure-sensitive adhesive became 130 μm, and the formed pressure-sensitive adhesive layer was bonded to an EVA film having a thickness of 100 μm, and a pressure-sensitive adhesive having a thickness of 230 μm. I got a tape.

<Comparative Example 8>
95 parts by mass of 2-ethylhexyl acrylate, 5 parts by mass of 2-hydroxyethyl acrylate, 0.2 parts by mass of Irgacure 651 (manufactured by BASF, 50% ethyl acetate solution) as a photo radical generator, and 0.01 parts by mass of lauryl mercaptan Was dissolved in ethyl acetate to obtain a solution. Polymerization was performed by irradiating this solution with ultraviolet rays to obtain an ethyl acetate solution of the polymer. Further, 3.5 parts by mass of 2-methacryloyloxyethyl isocyanate (manufactured by Showa Denko KK, Karenz MOI) was reacted with 100 parts by mass of the solid content of this solution, the weight average molecular weight was 700,000, An acrylic copolymer that was a crosslinked (meth) acrylic resin containing an ethylenically unsaturated group having a value of 12.2 mgKOH / g and an acid value of 0.9 mgKOH / g was synthesized.
1.0 part by mass of Irgacure 184 (manufactured by BASF) as a photopolymerization initiator and U-324A as a urethane acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd.) 2 0.040 parts by mass and 150 parts by mass of SE4050 (manufactured by Admatechs Co., Ltd.) as a filler were blended to obtain an adhesive composition.
The obtained pressure-sensitive adhesive composition was coated on a transparent release liner so that the thickness of the pressure-sensitive adhesive became 130 μm, and the formed pressure-sensitive adhesive layer was bonded to an EVA film having a thickness of 100 μm, and a pressure-sensitive adhesive having a thickness of 230 μm. I got a tape.

<Comparative Example 9>
A polymer solution having a weight average molecular weight of 200,000 was obtained by blending 2.0 mol% of methacrylic acid, 71 mol% of 2-ethylhexyl acrylate and 27 mol% of 2-hydroxyethyl acrylate, and polymerizing in the solution. 2-acryloyloxyethyl isocyanate is mixed in a solution of 20 parts by mass (produced by Showa Denko KK, Karenz AOI) with respect to 100 parts by mass of this polymer, and an ethylenically unsaturated group is introduced into the hydroxy group. An acrylic copolymer polymer containing a saturated group (weight average molecular weight: 300,000, hydroxyl value 12.3 mg KOH / g, acid value 7.8 mg KOH / g) was synthesized.
In this ethylenically unsaturated group-containing acrylic copolymer polymer, 1.5 parts by mass of Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent and 5.0 parts by mass of Irgacure 184 (manufactured by BASF) as a photopolymerization initiator. Partially blended to obtain a pressure-sensitive adhesive composition.
The obtained pressure-sensitive adhesive composition was coated on a transparent release liner so that the thickness of the pressure-sensitive adhesive was 150 μm, and the formed pressure-sensitive adhesive layer was bonded to an LDPE film having a thickness of 100 μm, and a pressure-sensitive adhesive having a thickness of 250 μm. I got a tape.

<Comparative Example 10>
96 mol% of butyl acrylate and 4 mol% of 2-hydroxyethyl acrylate were blended and polymerized in the solution to obtain a polymer solution having a weight average molecular weight of 700,000. The polymer had a hydroxyl value of 16.7 mgKOH / g and an acid value of 0 mgKOH / g.
To 100 parts by mass of the polymer, 2.5 parts by mass of Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.) was blended into the polymer solution to obtain an adhesive composition.
The obtained pressure-sensitive adhesive composition was applied onto a transparent release liner so that the thickness of the pressure-sensitive adhesive was 130 μm, and the formed pressure-sensitive adhesive layer was bonded to an LDPE film having a thickness of 100 μm, and a pressure-sensitive adhesive having a thickness of 230 μm. I got a tape.

The following tests were performed on the adhesive tapes produced in the above examples and comparative examples, and their performance was evaluated. The evaluation results are shown in Tables 1 and 2 below.

<Measurement and analysis>
Contact angle measurement and surface free energy calculation:
The surface of the base film on which the adhesive layer was not provided was fixed to a wafer with a flat surface using a double-sided tape.
Thereafter, the release liner was peeled off, and diiodomethane and pure water were dropped onto the pressure-sensitive adhesive layer at different positions, and the respective contact angles θ were measured using a FACE contact angle meter CA-S150 type manufactured by Kyowa Chemical Industry Co., Ltd. .
Next, in order to measure the contact angle of the pressure-sensitive adhesive layer cured by ultraviolet irradiation to diiodomethane and pure water, the pressure-sensitive adhesive tape was fixed to a wafer having a flat surface by the same method as described above. Subsequently, UV irradiation was performed from the release liner side using a high-pressure mercury lamp so that the integrated irradiation amount was 500 mJ / cm ² . After being left for 1 hour after UV irradiation, the release liner is peeled off, diiodomethane and pure water are dropped at different positions, and the respective contact angles θ are measured using the FACE contact angle meter CA-S150 type manufactured by Kyowa Chemical Industry Co., Ltd. Measured.
The value of the contact angle θ obtained above was substituted into the simultaneous equations of <Formula 1> described above, and the surface free energy of the pressure-sensitive adhesive layer surface was calculated.

Hydroxyl value:
The measurement was performed according to JIS K 0070.

Acid value:
It was measured according to JIS K5601-2-1: 1999.

<Test Example 1> Evaluation of Edge Floating Using a DR8500III (trade name) manufactured by Nitto Seiki Co., Ltd., a polyimide film [HD-8820 (trade name, Hitachi Chemical Co., Ltd.) having a thickness of 725 μm and a diameter of 8 inches on a silicon wafer. DuPont Microsystems) was formed, and the wafer surface was cleaned by etching with O ₂ plasma. The tape produced by the said Example and comparative example was bonded to this polyimide-attached wafer. Then, it grind | polished to 250 micrometers in thickness using the grinder [DFG8760 (brand name) by DISCO Corporation] with an in-line mechanism. This operation was performed 25 times on each tape. The ground wafer was stored in a transfer cassette, the lid of the cassette was closed, and the floating of the edge was visually observed.

(Edge lift evaluation criteria)
A: All the 25 sheets are not lifted. B: The floats are observed to be 12 sheets or less. C: The floats are observed to be 13 sheets or more.

<Test Example 2> Peelability test Peelability test on a wafer without bumps:
The pressure-sensitive adhesive tapes prepared in Examples and Comparative Examples were bonded to the surface of a polyimide-coated wafer prepared by the same method as in Test Example 1. After that, using a grinder having an inline mechanism [DFG8760 (trade name) manufactured by DISCO Corporation] until the thickness becomes 75 μm, a mounter RAD2700 having a inline mechanism (trade name, manufactured by Lintec Corporation) is used. Then, the adhesive tape was peeled from the ground wafer. Here, the adhesive tape of Comparative Example 5 to which the pressure-sensitive adhesive was applied was subjected to heat peeling at 50 ° C. In addition, the adhesive tapes of Examples 1 to 6 and Comparative Examples 1 to 4 and 6 to 10 to which the ultraviolet curable adhesive was applied were irradiated with ultraviolet rays using a high-pressure mercury lamp so that the cumulative irradiation amount was 500 mJ / cm ^2. And then peeled off.

(Peelability evaluation criteria)
A: All adhesive tapes can be peeled B: Peeling error (heat seal adhesion failure or tape cutting) occurs or cannot be peeled

Peelability test on bumped wafer:
A silicon wafer with bumps of 8 inches in diameter with solder bumps with a height of 100 μm and a bump pitch of 200 μm, and a copper pillar bump with a height of 50 μm and a bump pitch of 100 μm and an additional 7 μm polyimide film [HD-8820 (trade name, Hitachi Chemical DuPont Micro (Made by Systems Co., Ltd.)] The pressure-sensitive adhesive tapes produced in the above examples and comparative examples were bonded to the surface of the attached wafer. In the same manner as in the wafer without bumps, the wafers with solder bumps are ground to 100 μm thickness, and the wafers with copper pillar bumps are ground to 50 μm thickness. Was peeled off.

(Peelability evaluation criteria)
A: All adhesive tapes can be peeled B: Peeling error (peeling error due to heat seal adhesion or adhesive tape cutting) occurs or cannot be peeled

<Test Example 3> Evaluation of adhesive residue The wafer surface of the wafer with solder bumps and the wafer with copper pillar bumps from which the adhesive tape was peeled in Test Example 2 was observed with an optical microscope to evaluate the presence or absence of adhesive residue.

(Adhesive residue evaluation criteria)
A: No adhesive residue B: Adhesive residue on either wafer with copper pillar bump or solder bump C: Adhesive residue on either solder bump wafer or wafer with copper pillar bump

<Test Example 4> Adhesion test Using a DR8500III (trade name) manufactured by Nitto Seiki Co., Ltd. on the surface of a silicon wafer with bumps of 8 inches in diameter having solder bumps having a height of 100 μm and a bump pitch of 200 μm, the table temperature and the roller temperature. : Normal pressure (23 degreeC), Bonding pressure: The adhesive tape produced in the said Example and comparative example was bonded on the conditions of 0.4 MPa.
The adhesion at that time was confirmed visually, and the presence or absence of air mixing between the adhesive tape and the wafer was examined.

(Adhesion evaluation criteria)
A: No air mixing even after 48 hours after bonding B: Air mixing between 24 and 48 hours after bonding C: Air mixing between 24 and 24 hours after bonding

The results are shown in Table 1 below.

The pressure-sensitive adhesive tapes of Comparative Examples 1 to 4 are examples in which the surface free energy of the pressure-sensitive adhesive surface after ultraviolet (UV) irradiation is reduced. When the tapes of Comparative Examples 1 to 4 were used, edge floating due to cassette storage occurred with a high probability. Furthermore, the adhesive tapes of Comparative Examples 1 to 4 were inferior in at least one of the evaluation items of peelability, adhesive residue and adhesion.
The pressure-sensitive adhesives of Comparative Examples 5 and 10 use a pressure-sensitive adhesive, and edge floating tends to occur (Comparative Example 5), and a large amount of adhesive residue is generated at the time of peeling (Comparative Examples 5 and 10). As a result.
The pressure-sensitive adhesive tapes of Comparative Examples 6 to 8 are examples in which the surface free energy of the pressure-sensitive adhesive surface after UV irradiation increases, but the degree thereof is smaller than specified in the present invention. When the pressure-sensitive adhesive tapes of Comparative Examples 6 to 8 were used, adhesive residue was generated after peeling. Furthermore, the adhesive tapes of Comparative Examples 6 to 8 were inferior in at least one of the evaluation items of edge floating, peelability, and adhesion.
In the pressure-sensitive adhesive tape of Comparative Example 9, the surface free energy of the pressure-sensitive adhesive before UV irradiation is lower than the value specified in the present invention. Although the peeling force from the bump wafer was insufficient and no paste remained on the wafer with solder bumps, the paste remained on the copper pillar bump wafer with the polyimide film.

On the other hand, when the adhesive tapes of Examples 1 to 6 were used, there was no edge floating. Moreover, the adhesiveness which was excellent also with respect to the surface which has a 100-micrometer-high bump was shown, and even if it exceeded 48 hours after bonding, air mixing was not recognized. Furthermore, the adhesive tape was not cut at the time of peeling, and no adhesive residue was produced.

While this invention has been described in conjunction with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified and are contrary to the spirit and scope of the invention as set forth in the appended claims. I think it should be interpreted widely.

This application claims priority based on Japanese Patent Application No. 2014-205465 filed in Japan on October 6, 2014, which is hereby incorporated herein by reference. Capture as part.

DESCRIPTION OF SYMBOLS 10 Adhesive tape 11 Base film 12 Adhesive layer 13 Semiconductor wafer

Claims (8)

1. A bumped semiconductor wafer surface protecting adhesive tape having an ultraviolet curable adhesive layer on a substrate film,
   The pressure-sensitive adhesive layer contains a (meth) acrylic polymer having a weight average molecular weight of 10,000 to 2,000,000 and having a radiation-curable carbon-carbon double bond-containing group, a hydroxyl group, and a carboxy group.
   The surface free energy of the pressure-sensitive adhesive layer surface before ultraviolet irradiation is 25.5 mN / m or more and less than 35 mN / m,
   The surface of the pressure-sensitive adhesive layer after curing by ultraviolet irradiation has a surface free energy higher by 5 mN / m or more than the surface of the pressure-sensitive adhesive layer before ultraviolet irradiation,
   The surface of the pressure-sensitive adhesive layer after curing by ultraviolet irradiation has a smaller contact angle with respect to diiodomethane than the surface of the pressure-sensitive adhesive layer before ultraviolet irradiation,
   The (meth) acrylic polymer is obtained by reacting a polymer having a hydroxyl group and a carboxy group before introduction of a radiation-curable carbon-carbon double bond group with a compound having a radiation-curable carbon-carbon double bond group. 1 mol% to 10 mol% of (meth) acrylic acid in all the monomer components forming the polymer before the introduction of the radiation curable carbon-carbon double bond group,
   The hydroxyl value of the polymer constituting the pressure-sensitive adhesive layer surface is 30 to 100 mgKOH / g,
   A pressure-sensitive adhesive tape for protecting a semiconductor wafer with bumps, wherein an acid value of a polymer constituting the surface of the pressure-sensitive adhesive layer is 5 to 65 mgKOH / g.
2. 2. The bumped semiconductor wafer surface protecting adhesive tape according to claim 1, wherein the compound having a radiation curable carbon-carbon double bond group is 2- (meth) acryloyloxyethyl isocyanate.
3. 3. The bumped semiconductor according to claim 2, wherein the compounding amount of the 2- (meth) acryloyloxyethyl isocyanate is 1 to 20 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer. Adhesive tape for wafer surface protection.
4. 4. The bumped semiconductor wafer surface protecting adhesive according to claim 1, wherein a crosslinking agent is added in an amount of 0.1 to 5 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer. tape.
5. The adhesive tape for protecting a semiconductor wafer surface with bumps according to any one of claims 1 to 4, wherein the acid value of the polymer constituting the surface of the adhesive layer is 10 to 35 mgKOH / g.
6. A bumped semiconductor wafer processing method using the bumped semiconductor wafer surface protecting adhesive tape according to any one of claims 1 to 5, comprising the following steps (A) to (D): A method for processing a bumped semiconductor wafer.
   Step (A) Step of bonding the bumped semiconductor wafer surface protecting adhesive tape to the bump-formed surface of the semiconductor wafer with bumps Step (B) For protecting the bumped semiconductor wafer surface of the semiconductor wafer with bumps Step of grinding the surface opposite to the bonding surface of the adhesive tape Step (C) Step of curing the bumped semiconductor wafer surface protecting adhesive tape by irradiating the bumped semiconductor wafer surface protecting adhesive tape with ultraviolet rays And (D) peeling off the bumped semiconductor wafer surface protecting adhesive tape from the bumped semiconductor wafer.
7. The method for processing a semiconductor wafer with bumps according to claim 6, wherein the semiconductor wafer with bumps has an insulating layer on a bonding surface with the adhesive tape for protecting the surface of the semiconductor wafer with bumps.
8. The method for processing a semiconductor wafer with bumps according to claim 6 or 7, wherein the height of the bumps is 15 µm or more.

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