JP2016164972A - Adhesive tape for semiconductor wafer surface protection and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive tape for semiconductor wafer surface protection which can adhere tightly to a semiconductor wafer, in processing of the semiconductor wafer, and can be peeled without breakage of the semiconductor wafer and an adhesive deposit in peeling; and provide a semiconductor wafer processing method using the same.SOLUTION: An adhesive tape for semiconductor wafer is heated and bonded to the surface of a wafer having unevenness of 20 μm or more at a temperature of 60°C or higher, and includes at least three layers of a base material film, an intermediate resin layer and an adhesive layer. The base material film is formed of a polystyrene resin, has a melting point of higher than 90°C, and a bending modulus of 1-10 GPa. The intermediate resin layer has a thickness which is equal to the height of a bump or higher, a melting point in a range of 50-90°C, and a bending modulus of 1-100 MPa.SELECTED DRAWING: None

Description

  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, the thickness of the semiconductor wafer has been required to be about 200 to 400 μm by back grinding or the like. However, with the recent progress of high-density mounting technology, it is necessary to reduce the size of the semiconductor chip, and accordingly, the semiconductor wafer is becoming thinner. Depending on the type of semiconductor chip, it is necessary to make the semiconductor wafer as thin as about 100 μm. On the other hand, the diameter of the original wafer tends to be increased in order to increase the number of semiconductor chips that can be manufactured by one processing. 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 to increase the diameter of a semiconductor wafer simultaneously with the thinning of the semiconductor wafer is particularly remarkable in the field of flash memory in which 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.

  In addition to this, especially in recent years, with the spread of smartphones, mobile phone performance improvement, music player miniaturization, and performance improvement, wafers used for flip chip mounting using electrode wafers that take impact resistance into consideration However, the demand for thin film is increasing. In addition, with regard to the wafer with bumps, it has become necessary to perform thin film grinding of the wafer portion to 100 μm or less. Bumps for flip-chip connection have been densified to improve transfer speed, and the bump height (projection height from the wafer surface) has become lower, and the distance between the bumps has accordingly increased. It is getting shorter. In recent years, flip-chip connection has also been implemented in DRAMs, so that wafer thinning is also accelerated.

  Flip chip mounting has been attracting attention as a method for mounting a semiconductor element with a minimum area in response to recent downsizing and higher density of electronic devices. Bumps are formed on the electrodes of the semiconductor element used for the flip chip mounting, and the bumps are electrically joined to the wiring on the circuit board. As the composition of these bumps, solder or gold is mainly used. The solder bump or gold bump is formed on an exposed aluminum terminal connected to the internal wiring of the chip by vapor deposition or plating.

  However, wafers with bumps have large irregularities on the surface, making thin film processing difficult, and when back grinding is performed using normal adhesive tape, wafer cracking may occur or wafer thickness accuracy deteriorates. Or Therefore, the wafer with bumps is ground using a specially designed surface protection tape (see, for example, Patent Document 1).

  However, since these tapes sufficiently absorb bumps to ensure grindability, it is very difficult to achieve both releasability. The finished thickness of the chip that has been flip-chip mounted so far has a certain thickness of 200 μm or more, and has been able to be peeled off because of its rigidity. However, since the wafer finish thickness has become increasingly thinner and the bump density has increased recently, the tape has caused a problem that it cannot be easily peeled off. On the other hand, if the peelability is ensured, the adhesion becomes insufficient, causing intrusion of grinding water and residual glue during back grinding.

  On the other hand, the bump height of the wafer with bumps used in the wafer level package remains high, and bumps with a height of 250 μm or more are also mounted. Wafer level packages do not require stacking of chips, so they are not ground as thin as 50 μm or less like memory wafers. However, they have high bumps, so they are very easy to break even with thick film grinding and are 150 μm thick or less. The problem of wafer cracking easily occurs with the grinding thickness.

  A surface protection tape dedicated to such a wafer has been proposed (see Patent Documents 2 and 3).

JP 2001-203255 A Japanese Patent No. 5242830 Japanese Patent No. 5117630

However, with conventional radiation-curable adhesive tapes, when radiation-cured, the adhesive bites into the bumps and other irregularities on the surface of the semiconductor wafer, and the anchor effect becomes stronger, making it difficult to peel off. There has been a problem that the adhesive is left on the surface of the semiconductor wafer after the part is broken or peeled off. This problem becomes more conspicuous as bumps increase in bumps and the pitch between bumps decreases for the purpose of improving the reliability of semiconductors.

  Moreover, the method of processing the bump without completely following the adhesive (Patent Document 3) often has extremely good peelability. However, there still remains a problem that adhesive residue due to the inhibition of curing due to oxygen intervention easily occurs, cracks occur during grinding, and a problem of dust intrusion easily occurs.

  Accordingly, the present invention provides an adhesive tape for protecting a semiconductor wafer surface and a semiconductor using the same, which can be firmly adhered to a semiconductor wafer during processing of the semiconductor wafer and can be removed without being damaged or having adhesive residue at the time of peeling. It is an object of the present invention to provide a wafer processing method.

In view of the above problems, the present inventors have conducted intensive studies. As a result, at least a base film, an intermediate resin layer melted at a predetermined temperature, and a pressure-sensitive adhesive layer are bonded to the wafer surface by heating at a predetermined temperature. It is made of adhesive layers for semiconductor wafers, the thickness of the intermediate resin layer is equal to or higher than the bump height, and the melting point and tensile modulus of the base film and the melting point and bending modulus of the intermediate resin layer are specified respectively. It has been found that the above-mentioned conventional problems can be solved by setting the above range. That is, even when there are high bumps or when the pitch between bumps is narrowed, the semiconductor wafer is firmly attached to the semiconductor wafer during processing, and the thin film semiconductor wafer is not damaged or left unbonded during peeling. It has been found that an adhesive tape for protecting the surface of a semiconductor wafer that can be peeled can be provided. The present invention has been made based on this finding.
That is, the said subject was achieved by the following means.
(1) A semiconductor wafer pressure-sensitive adhesive tape that is bonded by heating at a temperature of 60 ° C. or higher to a wafer having irregularities of 20 μm or more on the wafer surface,
The semiconductor wafer pressure-sensitive adhesive tape comprises at least three layers of a base film, an intermediate resin layer, and a surface pressure-sensitive adhesive layer,
The base film is made of polystyrene resin, the melting point exceeds 90 ° C., and the flexural modulus is 1 GPa to 10 GPa,
The thickness of the intermediate resin layer is not less than the height of the bump, the melting point is in the range of 50 ° C. to 90 ° C., and the flexural modulus is 1 MPa to 100 MPa,
Adhesive sheet for semiconductor wafers.
(2) The adhesive sheet for a semiconductor wafer according to (1), wherein the intermediate resin layer is any one of ethylene-methyl acrylate copolymer resin, ethylene-ethyl acrylate copolymer resin, and ethylene-butyl acrylate copolymer resin.
(3) The thickness of the said base film is 25 micrometers-75 micrometers, The adhesive sheet for semiconductor wafers as described in (1) or (2) characterized by the above-mentioned.
(4) The adhesive sheet for a semiconductor wafer according to any one of (1) to (3), wherein the thickness of the intermediate resin layer is 100 μm to 400 μm.
In the present specification, the fact that the wafer surface has irregularities of 20 μm or more means that the semiconductor wafer has such depressions or protrusions. The height of the unevenness means the distance from the highest part to the wafer surface or the distance from the lowest part to the wafer surface. For example, when metal electrodes (bumps) are formed on a wafer, the highest portion is the top of the bump, and the distance from the top to the wafer surface is referred to as the uneven height. Alternatively, when a scribe line (dicing line) is formed on the wafer, the lowest part is the deepest part of the scribe line, and the distance from the surface to the wafer surface is called the height of the unevenness.

  According to the present invention, an adhesive tape for protecting a semiconductor wafer surface and a semiconductor that can be peeled off without causing breakage of the semiconductor wafer or residue of adhesive is greatly reduced by firmly adhering to the semiconductor wafer when processing the semiconductor wafer. A method for manufacturing a wafer can be provided.

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

[Semiconductor wafer surface protective adhesive tape]
In the pressure-sensitive adhesive tape for protecting a semiconductor wafer surface of the present invention, a radiation curable pressure-sensitive adhesive layer is formed on at least one surface of a base film.
Here, the radiation-curable pressure-sensitive adhesive layer refers to a pressure-sensitive adhesive layer that is cured by irradiation with radiation (for example, light such as ultraviolet rays (including laser light), ionizing radiation such as an electron beam). The radiation to be irradiated is preferably ultraviolet rays.

<Base film>
The melting point of the base film applied to the adhesive tape for protecting a semiconductor wafer surface of the present invention is higher than 90 ° C. By setting the melting point to be higher than 90 ° C., it is possible to prevent the fusion to the chuck table in the tape bonding process, and to bond sufficiently to the uneven wafer. Also, when DDF is bonded, DDF bonding can be performed while preventing fusion to the chuck table. The semiconductor wafer surface protective tape of the present invention has a sufficiently high temperature of 60 ° C. in order to improve the fluidity of the intermediate resin layer by applying heat to the intermediate resin layer and ensure sufficient adhesion to the uneven wafer. Used under heating conditions of ~ 90 ° C. Therefore, when the melting point of the base film is 90 ° C. or lower, the back surface of the base film is likely to melt and fuse with the chuck table. When the base film is a non-crystalline resin such as styrene, the bigat softening point is an index because a melting point is desired. When the Vicat softening point is exceeded, fluidity appears on the back surface of the base material, and the risk of entering the porous portion of the chuck table increases.
The flexural modulus of the base film applied to the present invention is preferably 1 GPa to 10 GPa, more preferably 2 GPa to 5 GPa. By setting the flexural modulus of the base film to a flexural modulus in this range, it is possible to exert a correction force against the warpage of the wafer itself, so that a thick polyimide film or an insulating film is formed in multiple layers. Therefore, the amount of warpage can be reduced even in a bump wafer where the warpage of the wafer is large. If the flexural modulus is less than 1 GPa, the wafer warp correction force is lost, and a bump wafer transport error occurs. On the other hand, if the flexural modulus of the base film exceeds 10 GPa, a peeling force is applied to the wafer when the tape is peeled, which causes a wafer crack.

The base film is preferably made of a resin film. Basically, plastics, rubbers, and the like that are usually used in this field can be used as long as the above conditions are satisfied. For example, polyolefin resin (polyethylene, polypropylene, ethylene-propylene copolymer, polybutene-1, poly-4-methylpentene-1, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid Α-olefin homopolymers or copolymers such as methyl copolymers, ethylene-acrylic acid copolymers, ionomers, or mixtures thereof), polyester resins (polyethylene terephthalate, polyethylene naphthalate), polycarbonate resins, polyurethane resins Engineering plastics (polymethyl methacrylate, etc.), synthetic rubbers (styrene-ethylene-butene or pentene copolymers), thermoplastic elastomers (polyamide-polyol copolymers, etc.), and mixtures thereof Thing, and the like. Moreover, you may use what made these two or more layers.
The base film is more preferably a polyester resin or a polystyrene resin, and more preferably a polystyrene resin containing a rubber component.
For this reason, in this invention, a base film uses what consists of polystyrene resins.

  The thickness of the base film is preferably 25 μm to 125 μm, more preferably 50 μm to 100 μm, in consideration of the balance between the warp correction force of the wafer and the peelability of the tape, cost, and manufacturing suitability. In the range of 50 μm to 100 μm, even when the bump wafer is ground to a thickness of 50 μm or less, it can be ground without any transport error, and the tape can be easily peeled off.

<Intermediate resin layer>
The adhesive tape for protecting the surface of a semiconductor wafer of the present invention requires an intermediate resin layer. By heat bonding the tape, the intermediate resin layer melts and follows the bumps completely. Furthermore, since it cools after bonding, dust penetration | invasion etc. can be prevented by hold | maintaining a bump completely. The melting point of the intermediate resin layer of the present invention is preferably in the range of 50 ° C to 90 ° C, more preferably 60 ° C to 80 ° C. Since the surface protective tape is heated and bonded at 50 ° C. or higher and the bumps need to be completely adhered by the intermediate resin layer at that time, the elastic modulus needs to change rapidly in this temperature range. The wafer is ground at a normal temperature, and if the resin flows at this temperature, the thickness accuracy at the time of grinding is extremely deteriorated, so that it is preferably highly elastic. On the other hand, since it is necessary to have low elasticity in order to sufficiently follow the unevenness when bonding, the intermediate resin layer is required to have contradictory performance. In order to realize this contradictory performance, it is necessary to include a melting point at which the fluidity changes extremely at the bonding temperature.
When the melting point of the intermediate resin layer is less than 50 ° C., it is difficult to form the base film, and the thickness accuracy is also deteriorated. On the other hand, when the melting point of the intermediate resin layer exceeds 90 ° C., it does not sufficiently follow the bumps even if the heat bonding is performed, so that dust intrusion and wafer cracking problems occur.

  Furthermore, the bending elastic modulus of the intermediate resin layer of the adhesive tape for protecting a semiconductor wafer surface of the present invention is 1 MPa to 100 MPa. By setting it as this range, the thickness accuracy after grinding can be maintained while relaxing the stress applied during wafer bonding. The warping of the tape itself can be suppressed by performing stress relaxation. When the flexural modulus of the intermediate resin layer is less than 1 MPa, it becomes difficult to form a film while maintaining the thickness accuracy as the base material. In addition, the thickness accuracy of the wafer after grinding also deteriorates. On the other hand, if the bending elastic modulus of the intermediate resin layer exceeds 100 MPa, the elastic modulus change is insufficient even when melted, and the case where the intermediate resin layer does not completely adhere to the bumps occurs.

The intermediate resin layer may be a resin layer or a resin film. The resin layer or resin film is simply a resin layer or resin film and is not intended for adhesion, and therefore non-adhesiveness is preferred. Non-adhesive means a state without stickiness at room temperature.
Such a resin layer or resin film may be, for example, an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-methyl acrylate copolymer, an ethylene-acrylic acid copolymer, an ionomer or the like. -Olefin homopolymers or copolymers or mixtures thereof. You may have two or more of these resin layers or resin films.

The resin layer or resin film used for the intermediate resin layer is preferably an ethylene-methyl acrylate copolymer resin, an ethylene-ethyl acrylate copolymer resin, or an ethylene-butyl acrylate copolymer resin from the viewpoint of adhesion to the bump wafer. Is done.
The copolymer content of the ethylene-acrylic copolymer resin is preferably 10% by mass to 35% by mass, and more preferably 15% by mass to 30% by mass.
From the viewpoint of production suitability, the intermediate resin layer is preferably a multilayer. It is easier to form a film than a single layer. In the case of multiple layers, the layer on the base film side is preferably low-density polyethylene, and the defect rate can be reduced when the intermediate resin layer of the multilayer is formed by extrusion, and the layer is manufactured at a low cost. Can do. The melting point when the intermediate resin layer is a multilayer is the melting point of the layer in contact with the pressure-sensitive adhesive layer.
The method of laminating the resin layer or the resin film is not particularly limited as long as the accuracy of the thickness of the resin layer or the resin film is within a range that does not affect the resin layer or the resin film, for example, Examples include film formation by coextrusion and bonding with an adhesive.

  The thickness of the intermediate resin layer needs to be greater than the bump height. If it is lower than the height of the bump, it will not adhere sufficiently, and dust intrusion and wafer cracking will occur. A preferable range of the intermediate resin layer is 10 μm to 30 μm thicker than the bump height. If the thickness is 30 μm or more, the thickness accuracy of the wafer may deteriorate, and the manufacturing cost also increases. Further, when manufacturing the bump portion of the bump wafer, an error of about 10 .mu.m is generated. Therefore, if there is a thickness of 10 .mu.m in addition to the average bump height, it is possible to fully follow with a margin.

<Adhesive layer>
(Adhesive)
The pressure-sensitive adhesive used for 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 irradiation with radiation (preferably ultraviolet rays), but a reactive group capable of undergoing a polymerization reaction by irradiation with radiation. It is preferable to include a polymer having at least one (hereinafter referred to as “radiation curable polymer”).
The pressure-sensitive adhesive preferably contains a radiation curable polymer as a main component. More specifically, the radiation 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 radiation 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.

Although there is no restriction | limiting in particular in the said radiation-curable polymer, For example, a (meth) acryl copolymer, polyester, ethylene or a styrene copolymer, and a polyurethane are mentioned.
In the present invention, a (meth) acrylic copolymer is preferred.

As a method for synthesizing the radiation curable polymer, for example, (a) in the case of a polymer having an ethylenically unsaturated group, an ethylenically unsaturated group is introduced by reacting a compound having an ethylenically unsaturated group with the polymer. 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 an ethylenically unsaturated group and a reactive group α or the monomer having a reactive group β used for the synthesis of 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.

-Compound whose reactive group is a hydroxyl group-
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 portion [for example, N-methylol (meth) acrylamide, N, N-bismethylol (meth) acrylamide], Allyl alcohol, etc.

-Compound whose reactive group is an amino group-
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.

-Compound whose reactive group is a cyclic acid anhydride-
Maleic anhydride, itaconic anhydride, fumaric anhydride, phthalic anhydride, etc.

-Compound whose reactive group is epoxy group or oxetanyl group-
Glycidyl (meth) acrylate, allyl glycidyl ether, 3-ethyl-3-hydroxymethyloxetane, etc.

-Compound whose reactive group is an isocyanate group-
(Meth) acryloyloxyalkyl isocyanate [for example, 2- (meth) acryloyloxyethyl isocyanate, 2- (meth) acryloyloxypropyl isocyanate], a part of the isocyanate group of the polyvalent isocyanate compound, a hydroxyl group or a carboxy group, and ethylene Urethanized with a compound having an unsaturated group [for example, 2 to 10 functional (meth) acrylic urethane acrylate oligomer], etc.

  In addition, as said urethane acrylate oligomer, hydroxyalkyl (meth) which has a hydroxyl group in alcohol parts, such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, pentaerythritol tri (meth) acrylate, for example 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.

-Compound 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. And a radiation curable pressure-sensitive adhesive layer can be formed. 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 the reactive group α is preferably reacted in an amount of 5 to 40 parts by mass, more preferably 10 to 30 parts by mass, and more preferably 10 to 20 parts by mass with respect to 100 parts by mass of the polymer having the reactive group β. More preferably, partial reaction is performed. The crosslinking reaction can occur by heating the pressure-sensitive adhesive at an appropriate temperature by a conventional method.
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.
As such (meth) acrylic acid ester, the alcohol part preferably has 1 to 12 carbon atoms. 1-10 are more preferable, as for carbon number of an alcohol part, 4-10 are further more preferable, The thing whose alcohol part is a branched alkyl is preferable, and 2-ethylhexyl (meth) acrylate is especially preferable.

The mass average molecular weight of the radiation curable polymer used in the pressure-sensitive adhesive layer is preferably 50,000 to 2,000,000, and when the polymer and another polymer are used in combination, the mass average molecular weight of the polymer used in combination may be within the above range. preferable.
If the mass average molecular weight of the polymer used for the pressure-sensitive adhesive layer exceeds 2,000,000, the polymerization becomes 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 less than 50000, the cohesive force of the polymer itself is lowered, and this is likely to cause glue residue. In the pressure-sensitive adhesive tape of the present invention, the polymer used in the pressure-sensitive adhesive layer preferably has a mass average molecular weight of 200,000 to 800,000.
The mass 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 mass average molecular weight in terms of polystyrene. It is calculated.

(Photopolymerization initiator)
The radiation curable pressure-sensitive adhesive layer can contain a photopolymerization initiator as necessary. As long as it reacts with the radiation which permeate | transmits a base material as a photoinitiator, there will be no restriction | limiting in particular, A conventionally well-known thing can be used. For example, benzophenones such as benzophenone, 4,4′-dimethylaminobenzophenone, 4,4′-diethylaminobenzophenone and 4,4′-dichlorobenzophenone, acetophenones such as acetophenone and diethoxyacetophenone, 2-ethylanthraquinone, t- Anthraquinones such as butylanthraquinone, 2-chlorothioxanthone, benzoin ethyl ether, benzoin isopropyl ether, benzyl, 2,4,5-triallylimidazole dimer (rophine dimer), acridine compound, acylphosphine oxide These may be used alone or in combination of two or more.
The addition amount of the photopolymerization initiator is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the resin having an ethylenically unsaturated group. More preferably, it is 0.5 to 3 parts by mass. When the amount of photopolymerization initiator added is large, radiation curing occurs at multiple points and suddenly occurs, resulting in increased curing shrinkage. Therefore, photopolymerization starts compared to conventional radiation-curing surface protection adhesive tapes. Reducing the amount of the agent is also useful from the viewpoint of suppressing curing shrinkage.

(Other additives)
If necessary, the radiation curable pressure-sensitive adhesive layer may contain a tackifier, a tackifier, a surfactant, or other modifiers. Moreover, you may add an inorganic compound filler suitably.
Examples of other additives include silicone acrylates (for example, silicone diacrylate, silicone hexaacrylate) and radiation 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.

(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 a polyvalent isocyanate compound, a polyvalent epoxy compound, a polyvalent aziridine compound, and a chelate compound. 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).

  In addition, 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 a radiation 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. , Dipentaerythritol hexaacrylate, 1,4-butylene glycol diacrylate, 1,6 hexanediol diacrylate, polyethylene glycol diacrylate, oligoester acrylate, and the like.

  In addition to these, 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. (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, and 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.

(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 the uneven shape, the storage elastic modulus before irradiation is preferably 30000 to 75000 Pa. More preferably, it is 35000-60,000 Pa. The storage elastic modulus of the pressure-sensitive adhesive after curing by radiation irradiation (after being cured by irradiating the entire pressure-sensitive adhesive layer so that the cumulative irradiation amount is 500 mJ / cm ^{2 in} terms of ultraviolet ray) 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)
Although the thickness of an adhesive layer is not specifically limited, 10-100 micrometers is preferable and 20-40 micrometers is more preferable.
In order to form the pressure-sensitive adhesive layer on the intermediate resin layer, as described above, at least one type of pressure-sensitive adhesive can be applied to at least one surface of the base film by a conventional method.

<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.

[Semiconductor wafer processing process using adhesive tape]
The usage method of the adhesive tape of this invention is not limited to the method of dicing after said back surface grinding. For example, it can be suitably used in the following dicing die bonding process.
Specifically, first, the adhesive tape for protecting a semiconductor wafer surface of the present invention is bonded to the circuit pattern surface (front surface) of the semiconductor wafer so that the radiation curable pressure-sensitive adhesive layer becomes the bonding surface. Next, the surface side of the semiconductor wafer having no circuit pattern is ground until the thickness of the semiconductor wafer reaches a predetermined thickness, for example, 10 to 200 μm. After that, the surface of the semiconductor wafer surface protecting adhesive tape is placed on the heating adsorption table with the surface facing down, and in that state, a dicing die bonding film is applied to the ground surface without the circuit pattern of the semiconductor wafer. You may paste. Thereafter, a heat seal type (thermal fusion type) or adhesive type release tape is adhered to the back surface of the base film of the semiconductor wafer surface protective adhesive tape to peel the semiconductor wafer surface protective adhesive tape from the semiconductor wafer.

[Usage form of adhesive tape]
<Bump (electrode) height>
The bump height applicable to the present invention is not particularly specified, but is used for bumps having a height of 20 μm to 250 μm.
<Bump density on the surface of the thin film semiconductor wafer (high density)>
The arrangement density of the applicable bumps of the pressure-sensitive adhesive tape of the present invention is not particularly limited, but a pitch more than twice the height of the bumps (from the apex in the height direction of the bumps to the height of the next arranged bumps). Applicable to the distance to the apex in the vertical direction). It is also used for a wafer in which bumps are uniformly arranged on the entire surface.
<Thickness of thin film semiconductor wafer>
The thickness of the thin-film semiconductor wafer ground by the processing method using the pressure-sensitive adhesive tape of the present invention is preferably 20 to 500 μm, more preferably 50 to 200 μm.
By using the processing method using the adhesive tape of the present invention, a thin film semiconductor wafer can be obtained with a high yield. This semiconductor wafer processing method is suitable as a manufacturing method for thin-film grinding of a wafer with electrodes of 50 μm or less.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

Reference example 1
Low-density polyethylene (LDPE) resin (Tosoh Corp., Petrocene 231F) and ethylene-methyl acrylate copolymer (EMA) resin (Arkema Corp., 28MA07) are extruded using an extruder, and the total thickness is 250 μm. An intermediate resin layer was created. The thickness of the LDPE layer was 30 μm, and the thickness of the EMA layer was 220 μm.
An adhesive (thickness 10 μm) was applied to a 50 μm thick polyethylene terephthalate film (G2C, manufactured by Teijin DuPont Films, Inc.), which is a base film, and the film was laminated to obtain a laminate A having a total thickness of 310 μm.
15 mol% of methyl methacrylate, 2.0 mol% of methacrylic acid, 57 mol% of 2-ethylhexyl acrylate, and 26 mol% of 2-hydroxyethyl acrylate were blended and polymerized in solution to obtain an acrylic copolymer polymer. 2-Methacryloyloxyethyl isocyanate is mixed in 100 parts by mass of this polymer in 20 parts by mass (Showa Denko Co., Ltd., Karenz MOI) solution and ethylenically unsaturated group is introduced into the hydroxy group. An acrylic copolymer polymer solution (polymer B solution) containing a group and having a molecular weight of 700,000 was obtained.
To 100 parts by mass of this polymer B solution, 2.0 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 are blended, A pressure-sensitive adhesive composition was obtained.
The obtained pressure-sensitive adhesive composition was coated on a transparent release liner so that the thickness of the pressure-sensitive adhesive after drying was 30 μm, and the pressure-sensitive adhesive composition was applied to remove almost all of the solvent. The liner was heat-dried at 120 ° C. for 2 minutes in a drying furnace. The release liner on which the pressure-sensitive adhesive layer having a thickness of 30 μm after drying was formed was bonded to the laminate A having a thickness of 310 μm to obtain a pressure-sensitive adhesive tape having a thickness of 340 μm.

Example 1
Polystyrene (PS) resin (Nippon Polystyrene Co., Ltd., G9305) and ethylene-methyl acrylate copolymer (EMA) resin (Arkema Co., Ltd., 28MA07) are extruded using an extruder and laminated B having a total thickness of 310 μm. It was created. The thickness of the PS layer was 60 μm, and the thickness of the EMA layer was 250 μm.
The pressure-sensitive adhesive composition prepared in Reference Example 1 was applied on a transparent release liner so that the thickness of the pressure-sensitive adhesive after drying was 30 μm, and the pressure-sensitive adhesive composition was applied to remove almost all the contained solvent. The release liner thus obtained was heated and dried at 120 ° C. for 2 minutes in a drying furnace. The release liner on which the pressure-sensitive adhesive layer having a thickness of 30 μm after drying was formed was bonded to the laminate B having a thickness of 310 μm to obtain a pressure-sensitive adhesive tape having a thickness of 340 μm.

Reference example 2
Low density polyethylene (LDPE) resin (Tosoh, Petrocene 231F) and ethylene-butyl acrylate copolymer (EBA) resin (Arkema, 30BA02) are extruded using an extruder, and the total thickness is 250 μm. An intermediate resin layer was created. The thickness of the LDPE layer was 30 μm, and the thickness of the EBA layer was 220 μm.
An adhesive (thickness 10 μm) is applied to a 50 μm-thick polyethylene naphthalate film (Teonex Q51, manufactured by Teijin DuPont Films Ltd.), which is a base film, and a laminate C having a total thickness of 310 μm is obtained by laminating the film. It was.
The pressure-sensitive adhesive composition prepared in Reference Example 1 was applied on a transparent release liner so that the thickness of the pressure-sensitive adhesive after drying was 30 μm, and the pressure-sensitive adhesive composition was applied to remove almost all the contained solvent. The release liner thus obtained was heated and dried at 120 ° C. for 2 minutes in a drying furnace. The release liner on which the pressure-sensitive adhesive layer having a thickness of 30 μm after drying was formed was bonded to the laminate C having a thickness of 310 μm to obtain a pressure-sensitive adhesive tape having a thickness of 340 μm.

Example 2
Polystyrene (PS) resin (Nippon Polystyrene Co., Ltd., G9305) and ethylene-butyl acrylate copolymer (EBA) resin (Arkema Co., 35BA40) are extruded using an extruder, and the laminate D has a total thickness of 310 μm. It was created. The thickness of the PS layer was 60 μm, and the thickness of the EBA layer was 250 μm.
The pressure-sensitive adhesive composition prepared in Reference Example 1 was applied on a transparent release liner so that the thickness of the pressure-sensitive adhesive after drying was 30 μm, and the pressure-sensitive adhesive composition was applied to remove almost all the contained solvent. The release liner thus obtained was heated and dried at 120 ° C. for 2 minutes in a drying furnace. The release liner on which the pressure-sensitive adhesive layer having a thickness of 30 μm after drying was formed was bonded to the laminate D having a thickness of 310 μm to obtain a pressure-sensitive adhesive tape having a thickness of 340 μm.

Reference example 3
Low density polyethylene (LDPE) resin (Tosoh, Petrocene 231F) and ethylene-methyl acrylate copolymer (EMA) resin (Nippon Polyethylene, EB140F) are extruded using an extruder, and the total thickness is 250 μm. An intermediate resin layer was prepared. The thickness of the LDPE layer was 30 μm, and the thickness of the EMA layer was 220 μm.
An adhesive (thickness 10 μm) was applied to a polyethylene terephthalate film (Lumirror S10, manufactured by Toray Industries, Inc.) having a thickness of 50 μm, which is a base film, and a laminate E having a total thickness of 310 μm was obtained by laminating the film.
The pressure-sensitive adhesive composition prepared in Reference Example 1 was applied on a transparent release liner so that the thickness of the pressure-sensitive adhesive after drying was 30 μm, and the pressure-sensitive adhesive composition was applied to remove almost all the contained solvent. The release liner thus obtained was heated and dried at 120 ° C. for 2 minutes in a drying furnace. The release liner on which the pressure-sensitive adhesive layer having a thickness of 30 μm after drying was formed was bonded to the laminate E having a thickness of 310 μm to obtain a pressure-sensitive adhesive tape having a thickness of 340 μm.

Example 3
Polystyrene (PS) resin (manufactured by Nippon Polystyrene Co., Ltd., G9401) and ethylene-vinyl acetate copolymer (EVA) resin (Mitsui / DuPont Chemical Co., Ltd., V5773W) were extruded using an extruder, and the total thickness was 310 μm. A laminate F was prepared. The thickness of the PS layer was 60 μm, and the thickness of the EVA layer was 250 μm.
The pressure-sensitive adhesive composition prepared in Reference Example 1 was applied on a transparent release liner so that the thickness of the pressure-sensitive adhesive after drying was 30 μm, and the pressure-sensitive adhesive composition was applied to remove almost all the contained solvent. The release liner thus obtained was heated and dried at 120 ° C. for 2 minutes in a drying furnace. The release liner on which the pressure-sensitive adhesive layer having a thickness of 30 μm after drying was formed was bonded to the laminate F having a thickness of 310 μm to obtain a pressure-sensitive adhesive tape having a thickness of 340 μm.

Reference example 4
Low density polyethylene (LDPE) resin (Tosoh, Petrocene 231F) and ethylene-butyl acrylate copolymer (EBA) resin (Arkema, 30BA02) are extruded using an extruder, and the total thickness is 250 μm. An intermediate resin layer was created. The thickness of the LDPE layer was 30 μm, and the thickness of the EBA layer was 220 μm.
An adhesive (thickness 10 μm) was applied to a 50 μm thick polyethylene terephthalate film (G2C, manufactured by Teijin DuPont Films Ltd.), which is a base film, and the film was laminated to obtain a laminate G having a total thickness of 310 μm.
The pressure-sensitive adhesive composition prepared in Reference Example 1 was applied on a transparent release liner so that the thickness of the pressure-sensitive adhesive after drying was 30 μm, and the pressure-sensitive adhesive composition was applied to remove almost all the contained solvent. The release liner thus obtained was heated and dried at 120 ° C. for 2 minutes in a drying furnace. The release liner on which the pressure-sensitive adhesive layer having a thickness of 30 μm after drying was formed was bonded to the laminate G having a thickness of 310 μm to obtain a pressure-sensitive adhesive tape having a thickness of 340 μm.

Comparative Example 1
Polystyrene (PS) resin (Toyo Styrene Co., Ltd., G100C) and ethylene-methyl acrylate copolymer (EMA) resin (Nippon Polyethylene Co., Ltd., EB140F) are extruded using an extruder and laminated with a total thickness of 310 μm. H was created. The thickness of the PS layer was 60 μm, and the thickness of the EMA layer was 250 μm.
The pressure-sensitive adhesive composition prepared in Reference Example 1 was applied on a transparent release liner so that the thickness of the pressure-sensitive adhesive after drying was 30 μm, and the pressure-sensitive adhesive composition was applied to remove almost all the contained solvent. The release liner thus obtained was heated and dried at 120 ° C. for 2 minutes in a drying furnace. The release liner on which the pressure-sensitive adhesive layer having a thickness of 30 μm after drying was formed was bonded to the laminate H having a thickness of 310 μm to obtain a pressure-sensitive adhesive tape having a thickness of 340 μm.

Comparative Example 2
An ethylene-vinyl acetate copolymer (EVA) resin (manufactured by Tosoh Corporation, Ultrasen 515) was extruded using an extruder to form an intermediate resin layer having a total thickness of 250 μm.
An adhesive (thickness 10 μm) was applied to a polyethylene terephthalate film (Lumirror S10, manufactured by Toray Industries, Inc.) having a thickness of 50 μm, which is a base film, and a laminate I having a total thickness of 310 μm was obtained by laminating the film.
The pressure-sensitive adhesive composition prepared in Reference Example 1 was applied on a transparent release liner so that the thickness of the pressure-sensitive adhesive after drying was 30 μm, and the pressure-sensitive adhesive composition was applied to remove almost all the contained solvent. The release liner thus obtained was heated and dried at 120 ° C. for 2 minutes in a drying furnace. The release liner on which the pressure-sensitive adhesive layer having a thickness of 30 μm after drying was formed was bonded to the laminate I having a thickness of 310 μm to obtain a pressure-sensitive adhesive tape having a thickness of 340 μm.

Comparative Example 3
A low density polyethylene (LDPE) resin (manufactured by Tosoh Corporation, Petrocene 231F) was extruded using an extruder to form an intermediate resin layer having a total thickness of 250 μm.
An adhesive (thickness 10 μm) was applied to a 50 μm thick polyethylene terephthalate film (Lumirror S10, manufactured by Toray Industries, Inc.) as a base film, and the film was laminated to obtain a laminate J having a total thickness of 310 μm.
The pressure-sensitive adhesive composition prepared in Reference Example 1 was applied on a transparent release liner so that the thickness of the pressure-sensitive adhesive after drying was 30 μm, and the pressure-sensitive adhesive composition was applied to remove almost all the contained solvent. The release liner thus obtained was heated and dried at 120 ° C. for 2 minutes in a drying furnace. The release liner on which the pressure-sensitive adhesive layer having a thickness of 30 μm after drying was formed was bonded to the laminate J having a thickness of 310 μm to obtain a pressure-sensitive adhesive tape having a thickness of 340 μm.

Comparative Example 4
High-density polyethylene (HDPE) resin (Nihonlon 2500, manufactured by Tosoh Corporation) and ethylene-vinyl acetate copolymer (EVA) resin (Ultrasen 541, manufactured by Tosoh Corporation) are extruded using an extruder, and the total thickness is 310 μm. A thick laminate K was created. The thickness of the HDPE layer was 60 μm, and the thickness of the EVA layer was 250 μm.
The pressure-sensitive adhesive composition prepared in Reference Example 1 was applied on a transparent release liner so that the thickness of the pressure-sensitive adhesive after drying was 30 μm, and the pressure-sensitive adhesive composition was applied to remove almost all the contained solvent. The release liner thus obtained was heated and dried at 120 ° C. for 2 minutes in a drying furnace. The release liner on which the pressure-sensitive adhesive layer having a thickness of 30 μm after drying was formed was bonded to the laminate K having a thickness of 310 μm to obtain a pressure-sensitive adhesive tape having a thickness of 340 μm.

Comparative Example 5
Extrusion molding of ethylene-vinyl acetate copolymer (EVA) resin (manufactured by Tosoh Corporation, Ultrasen 630) and ethylene-vinyl acetate copolymer (EVA) resin (manufactured by Tosoh Corporation, Ultrasen 627) with an extruder. A laminate L having a total thickness of 310 μm was prepared. The thickness of the EVA layer composed of Ultrasen 630 was 60 μm, and the thickness of the EVA layer composed of Ultrasen 627 was 250 μm.
The pressure-sensitive adhesive composition prepared in Reference Example 1 was applied on a transparent release liner so that the thickness of the pressure-sensitive adhesive after drying was 30 μm, and the pressure-sensitive adhesive composition was applied to remove almost all the contained solvent. The release liner thus obtained was heated and dried at 120 ° C. for 2 minutes in a drying furnace. The release liner on which the pressure-sensitive adhesive layer having a thickness of 30 μm after drying was formed was bonded to the laminate L having a thickness of 310 μm to obtain a pressure-sensitive adhesive tape having a thickness of 340 μm.

Comparative Example 6
A high-density polyethylene (HDPE) resin (Tosoh Corp., Nipolon Hard 2500) and a low-density polyethylene (LDPE) resin (Tosoh Corp., Petrocene 231F) are extruded using an extruder, and a laminate with a total thickness of 310 μm M was created. The thickness of the HDPE layer was 60 μm, and the thickness of the LDPE layer was 250 μm.
The pressure-sensitive adhesive composition prepared in Reference Example 1 was applied on a transparent release liner so that the thickness of the pressure-sensitive adhesive after drying was 30 μm, and the pressure-sensitive adhesive composition was applied to remove almost all the contained solvent. The release liner thus obtained was heated and dried at 120 ° C. for 2 minutes in a drying furnace. The release liner on which the pressure-sensitive adhesive layer having a thickness of 30 μm after drying was formed was bonded to the laminate M having a thickness of 310 μm to obtain a pressure-sensitive adhesive tape having a thickness of 340 μm.

Comparative Example 7
Low-density polyethylene (LDPE) resin (Tosoh Corp., Petrocene 231F) and ethylene-methyl acrylate copolymer (EMA) resin (Arkema Corp., 28MA07) are extruded using an extruder, and the total thickness is 310 μm. A laminate N was prepared. The thickness of the LDPE layer was 60 μm, and the thickness of the EMA layer was 250 μm.
The pressure-sensitive adhesive composition prepared in Reference Example 1 was applied on a transparent release liner so that the thickness of the pressure-sensitive adhesive after drying was 30 μm, and the pressure-sensitive adhesive composition was applied to remove almost all the contained solvent. The release liner thus obtained was heated and dried at 120 ° C. for 2 minutes in a drying furnace. The release liner on which the pressure-sensitive adhesive layer having a thickness of 30 μm after drying was formed was bonded to the laminate N having a thickness of 310 μm to obtain a pressure-sensitive adhesive tape having a thickness of 340 μm.

Comparative Example 8
High-density polyethylene (HDPE) resin (Nihonlon 2500, manufactured by Tosoh Corporation) and ethylene-vinyl acetate copolymer (EVA) resin (Ultrasen 541, manufactured by Tosoh Corporation) are extruded using an extruder, and the total thickness is 310 μm. A thick laminate O was created. The thickness of the HDPE layer was 60 μm, and the thickness of the LDPE layer was 250 μm.
100 parts by mass of solvent-based acrylic polymer (manufactured by Soken Chemical Co., Ltd., SK Dyne 1442), 0.5 part by mass of adduct isocyanate-based crosslinking agent Coronate L (trade name, manufactured by Nippon Polyurethane) and epoxy-based crosslinking 3.0 parts by mass of the agent TETRAD-X (trade name, manufactured by Mitsubishi Gas Chemical Company) was blended, and the concentration was adjusted with ethyl acetate 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 after drying was 30 μm, and the pressure-sensitive adhesive composition was applied to remove almost all of the solvent. The liner was heat-dried at 120 ° C. for 2 minutes in a drying furnace. The release liner on which the pressure-sensitive adhesive layer having a thickness of 30 μm after drying was formed was bonded to the laminate O having a thickness of 310 μm to obtain a pressure-sensitive adhesive tape having a thickness of 340 μm.

Comparative Example 9
An ethylene-vinyl acetate copolymer (EVA) resin (manufactured by Tosoh Corp., Ultrasen 760) is extruded to a substrate film of 50 μm thick polyethylene terephthalate film (Lumirror S10, manufactured by Toray Industries, Inc.) with a thickness of about 260 μm. It extruded so that the laminated body P might be obtained.
The pressure-sensitive adhesive composition prepared in Reference Example 1 was applied on a transparent release liner so that the thickness of the pressure-sensitive adhesive after drying was 30 μm, and the pressure-sensitive adhesive composition was applied to remove almost all the contained solvent. The release liner thus obtained was heated and dried at 120 ° C. for 2 minutes in a drying furnace. The release liner on which the pressure-sensitive adhesive layer having a thickness of 30 μm after drying was formed was bonded to the laminate P having a thickness of 310 μm to obtain a pressure-sensitive adhesive tape having a thickness of 340 μm.

Comparative Example 10
Low-density polyethylene (LDPE) resin (Tosoh, Petrocene 231F) and ethylene-vinyl acetate copolymer (EVA) resin (Tosoh, Ultrasen 541) are extruded using an extruder, and the total thickness is 250 μm. A thick intermediate resin layer was prepared. The thickness of the LDPE layer was 30 μm, and the thickness of the EBA layer was 220 μm.
An adhesive (10 μm thickness) was applied to a 50 μm thick polyethylene terephthalate film (Lumirror S10, manufactured by Toray Industries, Inc.) as a base film, and the film was laminated to obtain a laminate Q having a total thickness of 310 μm.
The pressure-sensitive adhesive composition prepared in Reference Example 1 was applied on a transparent release liner so that the thickness of the pressure-sensitive adhesive after drying was 30 μm, and the pressure-sensitive adhesive composition was applied to remove almost all the contained solvent. The release liner thus obtained was heated and dried at 120 ° C. for 2 minutes in a drying furnace. The release liner on which the pressure-sensitive adhesive layer having a thickness of 30 μm after drying was formed was bonded to the laminate Q having a thickness of 310 μm to obtain a pressure-sensitive adhesive tape having a thickness of 340 μm.

  About the adhesive tape produced by said Example, reference example, and a comparative example, the following tests were done and the performance was evaluated. The evaluation results are shown in Tables 1 and 2 below.

<Measurement and analysis>
<Test Example 1> Adhesion test (1) Adhesion to 50 μm bumps DR8500III (trade name) manufactured by Nitto Seiki Co., Ltd. on the surface of a silicon wafer with bumps having a diameter of 8 inches and Cu pillar bumps having a height of 50 μm and a bump pitch of 100 μm. Using 25 tapes prepared in the above examples, reference examples and comparative examples under conditions of a table temperature of 80 ° C. and a roller temperature of 60 ° C., a bonding pressure of 0.35 MPa, and a bonding speed of low (9 mm / sec). Bonded to the wafer. Under this bonding condition, the intermediate resin layer of the tape having an intermediate resin layer having a melting point of 80 ° C. or lower as a constituent layer was melted (the same was true in Test Example 2 below). 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.
(2) Adhesion to 200 μm bumps Using a DR8500III (trade name) manufactured by Nitto Seiki Co., Ltd. on the surface of a silicon wafer with 8 inches in diameter having solder bumps with a height of 200 μm and a bump pitch of 400 μm, a table temperature of 80 ° C. and Under the conditions of a roller temperature of 60 ° C., a bonding pressure of 0.35 MPa, and a low bonding speed (9 mm / sec), the tapes produced in the above examples, reference examples, and comparative examples were bonded to 25 wafers. 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)
○: No air mixing even after 48 hours after bonding ×: Air mixing within 48 hours after bonding

<Test Example 2> Grinding experiment (1) Dust penetration After each bump wafer used in adhesion evaluation was left for 48 hours after bonding, a grinder having an inline mechanism [DFG8760 (trade name) manufactured by DISCO Corporation] was used. Back grinding was performed on each of 25 bump wafers. Thereafter, the ground wafer was checked for silicon dust intrusion between the wafer and the tape. For the 50 μm bumps, back grinding was performed to a final grinding thickness of silicon of 50 μm, and for the 200 μm bumps, back grinding was performed to a final grinding thickness of silicon of 200 μm.
○: Dust intrusion was not observed in any bump wafer ×: Dust intrusion was observed in either bump wafer (2) Warp evaluation Warp of 25 50 μm high bump wafers used in evaluation of dust intrusion The quantity (height from the flat plate surface to the lower surface of the highest point of the warped wafer when the wafer was placed on the flat plate) was measured.
○: The average value of the warp amount was less than 5 mm. Δ: The average value of the warp amount was 5 mm or more and less than 10 mm. ×: The average value of the warp amount was 10 mm or more. (3) Peelability Evaluation About 25 bump wafers used in the evaluation of dust penetration, tape peeling was evaluated using a peeling device [RAD2700 (trade name) manufactured by DISCO Corporation].
○: Tape peeling error did not occur ×: Tape peeling error occurred

<Test Example 3> Thickness Accuracy Test Tapes prepared in Examples, Reference Examples, and Comparative Examples were bonded to 25 mirror wafers. The bonding conditions are the same as the conditions bonded in Test Example 2. Thereafter, using a grinder having an inline mechanism [DFG8760 (trade name) manufactured by DISCO Corporation], back grinding and dry polishing were performed on each of the 25 mirror wafers until the final thickness reached 100 μm. Thereafter, the thickness accuracy TTV (maximum thickness-minimum thickness) of the wafer surface was measured using SemiDex (thickness accuracy measurement device, manufactured by ISIS). The entire surface of the wafer (range of 200 mm × 200 mm) is measured at a measurement interval of X direction: 0.1 mm and Y direction: 10 mm.
○: TTV was less than 6 μm ×: TTV was 6 μm or more

<Test Example 4> Heat resistance test Tapes prepared in Examples, Reference Examples and Comparative Examples were bonded to mirror wafers. The bonding conditions are the same as the conditions bonded in Test Example 2. Thereafter, the tape surface was left facing for 3 minutes on a hot plate heated to 90 ° C., and then the tape surface was visually observed.
○: The tape surface (back of the base film) was not melted ×: The tape surface was melted

<Test Example 5> Various physical properties The melting point and Vicat softening point of the base film were measured based on JIS K 7206. Moreover, about the bending elastic modulus, it measured based on JISK6924-2.

Since the adhesive tapes of Comparative Examples 1 and 5 lacked heat resistance, melting of the substrate occurred in the heat resistance evaluation. For this reason, there is a high possibility that the problem of chuck table fusion occurs in the actual DAF bonding process. About the adhesive tape of Comparative Examples 2-6 and Comparative Examples 8-10, even if it heat-bonded, it became a result which does not contact | adhere to a bump wafer. Therefore, when grinding a bumped pattern wafer, dimples (uneven marks) are generated on the back surface, and there is a high possibility that the wafer will be cracked. In Comparative Examples 4 to 8, the warpage is not sufficiently suppressed, and there is a high possibility that a wafer handling error will occur. Further, there is a possibility that the edge portion touches the cassette due to warping when the cassette is stored, and an edge crack is generated. In Comparative Example 9, the EVA resin was laminated on the PET film by extrusion, but there was a problem in the thickness accuracy of the EVA resin, and a problem occurred in the film molding itself. Accordingly, the film thickness accuracy was extremely poor, and accordingly, the wafer thickness accuracy (TTV) after grinding was extremely poor.
On the other hand, the adhesive tape described in the examples resulted in excellent adhesion to the bump wafer, peelability from the bump wafer, warpage prevention, heat resistance, dust penetration prevention, and thickness accuracy.

The present invention relates to a semiconductor wafer surface protecting pressure-sensitive adhesive tape, a method for producing the same, 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, a manufacturing method thereof, and a processing method of the semiconductor wafer.

Therefore, the present invention provides an adhesive tape for protecting the surface of a semiconductor wafer, a method for producing the same, and a method for producing the same, which can be firmly adhered to a semiconductor wafer during processing of the semiconductor wafer, and can be removed without damaging the semiconductor wafer or leaving adhesive residue at the time of peeling. It is an object of the present invention to provide a method for processing a semiconductor wafer using the above.

In view of the above problems, the present inventors have conducted intensive studies. As a result, at least a base film, an intermediate resin layer melted at a predetermined temperature, and a pressure-sensitive adhesive layer are bonded to the wafer surface by heating at a predetermined temperature. It is made of adhesive layers for semiconductor wafers, the thickness of the intermediate resin layer is equal to or higher than the bump height, and the melting point and tensile modulus of the base film and the melting point and bending modulus of the intermediate resin layer are specified respectively. It has been found that the above-mentioned conventional problems can be solved by setting the above range. That is, even when there are high bumps or when the pitch between bumps is narrowed, the semiconductor wafer is firmly attached to the semiconductor wafer during processing, and the thin film semiconductor wafer is not damaged or left unbonded during peeling. It has been found that an adhesive tape for protecting the surface of a semiconductor wafer that can be peeled can be provided. The present invention has been made based on this finding.
That is, the said subject was achieved by the following means.
(1) A semiconductor wafer pressure-sensitive adhesive tape that is bonded by heating at a temperature of 60 ° C. or higher to a wafer having irregularities of 20 μm or more on the wafer surface,
The semiconductor wafer pressure-sensitive adhesive tape comprises at least three layers of a base film, an intermediate resin layer, and a surface pressure-sensitive adhesive layer,
The base film is made of polystyrene resin, the bigat softening point exceeds 90 ° C., and the flexural modulus is 1 GPa to 10 GPa,
The thickness of the intermediate resin layer is not less than the height of the bump, the melting point is in the range of 50 ° C. to 90 ° C., the flexural modulus is 1 MPa to 100 MPa , and
The pressure-sensitive adhesive of the pressure-sensitive adhesive layer is a solvent-based pressure-sensitive adhesive ,
Adhesive tape for semiconductor wafers.
(2) the intermediate resin layer is an ethylene - methyl acrylate copolymer resins, et styrene - butyl acrylate copolymer resins, ethylene - for a semiconductor wafer according to, characterized in that either vinyl acetate copolymer resin (1) Adhesive tape .
(3) A semiconductor wafer pressure-sensitive adhesive tape that is heat bonded to a wafer having an unevenness of 20 μm or more on the wafer surface at a temperature of 60 ° C. or higher,
The semiconductor wafer pressure-sensitive adhesive tape comprises at least three layers of a base film, an intermediate resin layer, and a surface pressure-sensitive adhesive layer,
The base film is made of polystyrene resin, the bigat softening point exceeds 90 ° C., and the flexural modulus is 1 GPa to 10 GPa,
The thickness of the intermediate resin layer is not less than the height of the bump, the melting point is in the range of 50 ° C. to 90 ° C., the flexural modulus is 1 MPa to 100 MPa, and the intermediate resin layer is an ethylene-methyl acrylate copolymer resin or It is any of ethylene-butyl acrylate copolymer resin,
Adhesive tape for semiconductor wafers.
(4) The adhesive tape for a semiconductor wafer according to any one of (1) to (3), wherein the thickness of the base film is 25 μm to 75 μm.
( 5 ) The adhesive tape for a semiconductor wafer according to any one of (1) to ( 4 ), wherein the thickness of the intermediate resin layer is from 100 μm to 400 μm.
(6) The method for producing a pressure-sensitive adhesive tape for a semiconductor wafer according to any one of (1) to (5),
A method for producing a pressure-sensitive adhesive tape for a semiconductor wafer, wherein a pressure-sensitive adhesive layer is formed using a solvent-based pressure-sensitive adhesive.
In the present specification, the fact that the wafer surface has irregularities of 20 μm or more means that the semiconductor wafer has such depressions or protrusions. The height of the unevenness means the distance from the highest part to the wafer surface or the distance from the lowest part to the wafer surface. For example, when metal electrodes (bumps) are formed on a wafer, the highest portion is the top of the bump, and the distance from the top to the wafer surface is referred to as the uneven height. Alternatively, when a scribe line (dicing line) is formed on the wafer, the lowest part is the deepest part of the scribe line, and the distance from the surface to the wafer surface is called the height of the unevenness.

According to the present invention, a semiconductor wafer surface protecting pressure-sensitive adhesive tape that can be peeled off without causing breakage of the semiconductor wafer or residue of adhesive, and the like can be greatly reduced by firmly adhering to the semiconductor wafer when processing the semiconductor wafer. A manufacturing method and a manufacturing method of a semiconductor wafer can be provided.

<Base film>
The melting point of the base film applied to the adhesive tape for protecting a semiconductor wafer surface of the present invention is higher than 90 ° C. By setting the melting point to be higher than 90 ° C., it is possible to prevent the fusion to the chuck table in the tape bonding process, and to bond sufficiently to the uneven wafer. Also, when DDF is bonded, DDF bonding can be performed while preventing fusion to the chuck table. The semiconductor wafer surface protective tape of the present invention has a sufficiently high temperature of 60 ° C. in order to improve the fluidity of the intermediate resin layer by applying heat to the intermediate resin layer and ensure sufficient adhesion to the uneven wafer. Used under heating conditions of ~ 90 ° C. Therefore, when the melting point of the base film is 90 ° C. or lower, the back surface of the base film is likely to melt and fuse with the chuck table. For the base film, for example, non-crystalline resins as styrene, fried Bigatto a softening point such exists melting point is indicative. When the Vicat softening point is exceeded, fluidity appears on the back surface of the base material, and the risk of entering the porous portion of the chuck table increases.
The flexural modulus of the base film applied to the present invention is preferably 1 GPa to 10 GPa, more preferably 2 GPa to 5 GPa. By setting the flexural modulus of the base film to a flexural modulus in this range, it is possible to exert a correction force against the warpage of the wafer itself, so that a thick polyimide film or an insulating film is formed in multiple layers. Therefore, the amount of warpage can be reduced even in a bump wafer where the warpage of the wafer is large. If the flexural modulus is less than 1 GPa, the wafer warp correction force is lost, and a bump wafer transport error occurs. On the other hand, if the flexural modulus of the base film exceeds 10 GPa, a peeling force is applied to the wafer when the tape is peeled, which causes a wafer crack.

Claims (4)

A pressure-sensitive adhesive tape for a semiconductor wafer that is heat bonded to a wafer having an unevenness of 20 μm or more on the wafer surface at a temperature of 60 ° C. or higher,
The semiconductor wafer pressure-sensitive adhesive tape comprises at least three layers of a base film, an intermediate resin layer, and a surface pressure-sensitive adhesive layer,
The base film is made of polystyrene resin, the melting point exceeds 90 ° C., and the flexural modulus is 1 GPa to 10 GPa,
The thickness of the intermediate resin layer is not less than the height of the bump, the melting point is in the range of 50 ° C. to 90 ° C., and the flexural modulus is 1 MPa to 100 MPa,
Adhesive sheet for semiconductor wafers.   The pressure-sensitive adhesive sheet for a semiconductor wafer according to claim 1, wherein the intermediate resin layer is one of ethylene-methyl acrylate copolymer resin, ethylene-ethyl acrylate copolymer resin, and ethylene-butyl acrylate copolymer resin.   The thickness of the said base film is 25 micrometers-75 micrometers, The adhesive sheet for semiconductor wafers of Claim 1 or 2 characterized by the above-mentioned.   The pressure-sensitive adhesive sheet for a semiconductor wafer according to any one of claims 1 to 3, wherein the thickness of the intermediate resin layer is 100 µm to 400 µm.