JP2023053783A - Film for back grind step and film for back grind step with adhesive layer - Google Patents

Abstract

To provide a film for back grind step which is improved in workability when sticking a film to a semiconductor wafer or a surface of the semiconductor wafer, in which a circuit is formed, including the circuit, has excellent detachability even in the step of detaching the film for back grind step therefrom, and is appropriately available for a back grind step.SOLUTION: The present invention relates to a film for back grind step used for a grinding step of a semiconductor wafer and consisting of at least two layers. The film for back grind step comprises a layer (A) at the side of a surface in contact with a surface at an opposite side of a surface to be ground in the semiconductor wafer. A resin composition constituting the layer (A) contains a thermoplastic resin (i) having a crystal fusion peak in a range of 60 to 120°C. A layer (B) is included in an outermost layer of a film surface at an opposite side of the layer (A), and a resin composition constituting the layer (B) contains a thermoplastic resin (ii) having a crystal fusion peak at 120°C or higher.

Description

The present invention relates to a film suitable for use in semiconductor wafer processing steps. The present invention also relates to a film used in a back grinding step of polishing a wafer and a back grinding step of polishing a surface of a wafer having a circuit formed thereon, opposite to the surface having the circuit, among semiconductor wafer processing steps.

Conventionally, adhesive films (tapes), stickers, labels, marking films, decorative sheets, etc., which are pasted to give design to signboards, automobiles, etc., have had colorability, workability, Films made of polyvinyl chloride resin (hereinafter also referred to as "PVC-based films"), which are excellent in scratch resistance, weather resistance, etc., are frequently used as substrates.

The PVC-based film itself has rigidity, but a plasticizer is added for the purpose of imparting flexibility so that it can function as an adhesive film. However, depending on the plasticizer used, there is a problem that the compatibility with the adhesive is poor, the stability is poor when the adhesive film is formed, and the plasticizer bleeds out significantly. In addition, there is a tendency to tighten restrictions on the use of plasticizers themselves.
Therefore, polyolefin-based resin films have been widely used as materials to replace PVC-based films.

Also, in the process of manufacturing semiconductors, adhesive films for semiconductor wafer processing are used when cutting semiconductor wafers and packages. ing.
Films using PVC-based or polyolefin-based resins have been developed as such films for semiconductor manufacturing processes (for example, Patent Document 1).

Furthermore, in recent years, semiconductor elements have become smaller and thinner, and semiconductor wafers are generally polished to be thin. In the polishing of semiconductor wafers, for the purpose of protecting the semiconductor wafer or, if a circuit is formed, the surface of the circuit, the adhesive film as described above is applied in the polishing step (hereinafter referred to as the "back grinding step"). ), it is used by being pressure-bonded to a semiconductor wafer (for example, Patent Document 2).
In addition, in the step of peeling off the adhesive film after polishing, problems such as transfer of the adhesive to the wafer or circuit side, peeling failure, and film breakage due to the strong adhesive force may occur. Furthermore, when it is used as an adhesive film, a step of laminating an adhesive is required, which has a large impact on economic efficiency.

In order to solve these problems, a backing having excellent workability when bonding a film to the circuit-bearing surface of a wafer or a circuit-formed wafer and having good peelability in the process of peeling the film from them is provided. There was a request for a film for the grinding process.

JP-A-9-8111 JP 2012-253373 A

In view of such problems, the present invention provides excellent workability when bonding a film to the circuit-bearing surface of a wafer or a circuit-formed wafer, and also exhibits good peelability in the step of peeling the film from them. It is an object of the present invention to provide a film for a back grinding process having

The present inventor has completed the present invention as a result of earnestly studying a film for solving the above problems.

That is, the gist of the present invention is as follows.
[1]
A back-grinding process film comprising at least two layers used in a semiconductor wafer polishing process,
It has a layer (A) on the side of the semiconductor wafer that contacts the side opposite to the side to be polished, and the resin composition that constitutes the layer (A) contains crystals within the range of 60 to 120 ° C. containing a thermoplastic resin (i) having a melting peak, and
The film has a layer (B) as the outermost layer on the film surface opposite to the layer (A), and the resin composition constituting the layer (B) has a crystalline melting peak of 120 ° C. or higher. containing a plastic resin (ii),
The film for the back grinding process.
[2]
The film for a back grinding process according to [1], wherein the layer (A) is in contact with a circuit-bearing surface of a circuit-bearing semiconductor wafer.
[3]
For the back grinding process according to [1] or [2], wherein the thermoplastic resin (i) contained in the layer (A) is one or more selected from the group consisting of polyolefin resins and styrene elastomers. the film.
[4]
The film for a back grinding process according to any one of [1] to [3], wherein the layer (A) has a thickness of 1 to 20 μm and the thickness of all layers is 30 to 300 μm.
[5]
The film for back grinding process according to [4], wherein the layer (B) has a thickness of 1 to 20 μm.
[6]
A film for back grinding process with an adhesive layer, which is obtained by laminating an adhesive layer on one surface of the film for back grinding process described in any one of [1] to [5].

According to the present invention, a film for a back grinding process which is excellent in workability when bonding a film to a wafer or a circuit-formed surface of a wafer, and which has good peelability in the process of peeling the film from them. can be provided.

Although the present invention will be described in detail below, the present invention is not limited to the following embodiments, and can be implemented with various modifications within the scope of the gist thereof. In addition, when the expression "~" is used in this specification, it is used as an expression including numerical values or physical property values before and after it.

One embodiment of the present invention is a backgrinding process film comprising at least two layers for use in a semiconductor wafer polishing process, comprising:
It has a layer (A) on the side of the semiconductor wafer that contacts the side opposite to the side to be polished, and the resin composition that constitutes the layer (A) contains crystals within the range of 60 to 120 ° C. containing a thermoplastic resin (i) having a melting peak, and
The film has a layer (B) as the outermost layer on the film surface opposite to the layer (A), and the resin composition constituting the layer (B) has a crystalline melting peak of 120 ° C. or higher. A film for a back grinding process containing a plastic resin (ii). (Hereinafter, it is also referred to as "the film for the back grinding process of the present invention".)

<Thermoplastic resin>
In the resin composition constituting the layer (A) on the side of the film for a back grinding process of the present invention, which is in contact with the side opposite to the side of the semiconductor wafer to be polished, the temperature is within the range of 60 to 120°C. contains as an essential component a thermoplastic resin (i) having a crystalline melting peak at .
The thermoplastic resin (i) that can be used in the layer (A) is any thermoplastic resin that has a crystalline melting peak in the range of 60 to 120 ° C., regardless of the material. Although a plastic resin may be used, it is preferable to use one or more selected from the group consisting of polyolefin resins and styrene elastomers. In one aspect of the film for back grinding process of the present invention, the thermoplastic resin (i) is a polyolefin resin.
In one aspect of the film for back grinding process of the present invention, the thermoplastic resin (i) is a styrene elastomer.

Polyolefin resins are easy to obtain, relatively easy to adjust heat resistance and flexibility, and are used in the back grinding process, which is one of the semiconductor processing processes, in the process of bonding to the wafer. It is preferably used because it has good workability in and peelability from a wafer.
As the type of polyolefin-based resin, one or more resins selected from polypropylene-based resins, polyethylene-based resins, and olefin-based elastomers are preferable from the viewpoint of availability, flexibility, handling, economy, etc. used for

Further, since the crystalline melting peak of the thermoplastic resin (i) is within the range of 60 to 120° C., the layer (A) side of the film for a back grinding process having the layer (A) described later can be heated. can be sufficiently adhered to the wafer in the step of bonding the to the semiconductor wafer. Furthermore, even when bonding to the circuit-bearing surface of a semiconductor wafer on which circuits are formed, it is possible to sufficiently conform to the unevenness of the circuit at the temperature during heating. A more preferred range of the crystal melting peak is 65 to 115°C, and a more preferred range is 70 to 110°C.

The processing temperature for laminating the film for the back grinding process having the layer (A) containing the thermoplastic resin (i) and the semiconductor wafer is in the range of 60 to 120° C. from the viewpoint of the crystal melting peak of the resin. preferably within If the temperature is within the range of 60 to 120° C., the layer (A) of the film for the back-grinding process is sufficiently melted so as to conform to the surface having the circuit of the semiconductor wafer provided with the circuit and the semiconductor wafer having the circuit formed thereon. becomes possible. When the temperature is 60° C. or higher, the resin is sufficiently melted and can follow the semiconductor wafer, thereby providing adhesion. If it is 120° C. or less, the film does not become too soft even when heated, and the handleability of the film does not deteriorate. A more preferred range of processing temperature is 65 to 115°C, and a more preferred range is 70 to 110°C.

Further, a thermoplastic resin (ii) having a crystalline melting peak of 120° C. or higher is added to the resin composition constituting the layer (B) located in the outermost layer on the film surface opposite to the layer (A) of the film. must be included. By having a crystal melting peak of 120 ° C. or higher, the film does not completely melt even at the temperature when performing processing such as bonding with the semiconductor wafer described above, and the film shape can be maintained. It is also an excellent film.
As the thermoplastic resin (ii) that can be used for the layer (B), any available thermoplastic resin can be used regardless of the material, as long as it is a thermoplastic resin having a crystal melting peak of 120° C. or higher. However, it is preferable to use a polyolefin resin.
Polyolefin resins are preferably used because they are readily available and relatively easy to adjust for heat resistance and flexibility.
As the type of polyolefin-based resin, one or more resins selected from polypropylene-based resins, polyethylene-based resins, and olefin-based elastomers are preferable from the viewpoint of availability, flexibility, handling, economy, etc. used for

As a method for measuring the crystalline melting peaks of thermoplastic resin (i) and thermoplastic resin (ii), for example, a differential scanning calorimeter is used, and a predetermined amount of a sample is weighed and heated at a rate of 10° C./min. After raising the temperature from 25 ° C. to 230 ° C., lowering the temperature to 25 ° C. at a cooling rate of 10 ° C./min, and again raising the temperature to 230 ° C. at a heating rate of 10 ° C./min. can be done.
Here, as a sample, in addition to using the thermoplastic resin itself, a film containing the thermoplastic resin can be used to measure the crystalline melting peak.

Examples of polypropylene-based resins that can be used in the film for the back grinding process of the present invention include homopolymers of propylene (homopolypropylene), and mixtures of propylene containing propylene as a main component and other monomers copolymerizable with propylene. Examples include copolymers (random polypropylene, block polypropylene), mixtures thereof, and the like.
Copolymers containing propylene as the main component and other copolymerizable monomers include random copolymers (random polypropylene) and block copolymers of propylene and ethylene or other α-olefins ( block polypropylene), block copolymers or graft copolymers containing a rubber component, and the like.
The α-olefin used as another monomer copolymerizable with propylene preferably has 4 to 12 carbon atoms, such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 4-methyl-1-pentene, 1-decene and the like can be mentioned, and one or a mixture of two or more thereof can be used.

Examples of the polyethylene-based resin that can be used in the film for the back grinding process of the present invention include ethylene homopolymers, ethylene-based copolymers of ethylene and other copolymerizable monomers, For example, low-density polyethylene (LDPE), high-pressure low-density polyethylene, linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), ethylene-based copolymer obtained by polymerization using a metallocene-based catalyst (metallocene-based polyethylene), ethylene-vinyl acetate copolymer, ethylene-methyl (meth)acrylate copolymer, ethylene-ethyl (meth)acrylate copolymer, ethylene-butyl (meth)acrylate copolymer, ethylene-( Examples thereof include metal ion crosslinked resins (ionomers) of meth)acrylic acid copolymers and ethylene-(meth)acrylic acid copolymers.
Among them, high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), from the viewpoint of ease of availability, handling of the resin, and ease of adjustment of the flexibility of the resulting film ) is preferably used.

An olefinic elastomer is a soft resin containing a polyolefinic resin and a rubber component. The rubber component may be dispersed in the polyolefinic resin, or they may be copolymerized with each other.
Specific examples of the olefinic elastomer that can be used in the film for the back grinding process of the present invention include, for example, ethylene-propylene copolymer elastomer, ethylene-1-butene copolymer elastomer, and propylene-1-butene copolymer. elastomer, ethylene-propylene-1-butene copolymer elastomer, ethylene-1-hexene copolymer elastomer, ethylene-1-octene copolymer elastomer, ethylene-styrene copolymer elastomer, ethylene-norbornene copolymer elastomer, Propylene-1-butene copolymer elastomers, ethylene-propylene-nonconjugated diene copolymer elastomers, ethylene-1-butene-nonconjugated diene copolymer elastomers, and ethylene-propylene-1-butene-nonconjugated diene copolymer elastomers Amorphous elastic copolymers containing olefin as a main component, such as coalesced elastomers, derivatives thereof, acid-modified derivatives, and the like can be mentioned.
Ethylene-propylene copolymer elastomers, ethylene-1-butene copolymer elastomers, propylene-1-butene copolymer elastomers, and ethylene-propylene-1-butene copolymer elastomers are preferred.

Among the polypropylene-based resins, polyethylene-based resins, and olefin-based elastomers, those having a crystalline melting peak within the range of 60 to 120 ° C. as the thermoplastic resin (i) used in the layer (A) include polyethylene-based From the viewpoint of adjusting the crystal melting peak, it is preferable to use a resin or an olefin-based elastomer.
Examples of the polyethylene-based resin used in the layer (A) include low-density polyethylene (LDPE), high-pressure low-density polyethylene, linear low-density polyethylene (LLDPE), and ethylene-based copolymer obtained by polymerization using a metallocene-based catalyst. Copolymer (metallocene polyethylene), ethylene-vinyl acetate copolymer, ethylene-methyl (meth)acrylate copolymer, ethylene-ethyl (meth)acrylate copolymer, ethylene-butyl (meth)acrylate copolymer , ethylene-(meth)acrylic acid copolymer, metal ion crosslinked resin (ionomer) of ethylene-(meth)acrylic acid copolymer, and the like.
Specific examples of polyethylene resins having a crystalline melting peak in the range of 60 to 120° C. include "Novatec LD", "Novatec EVA", "Rexpearl ET", "Rexpearl EMA", and "Rexpearl EEA." ”, “Metallocene Plastomer Kernel” (manufactured by Nippon Polyethylene), “Evaflex”, “Himilan”, “Nucrel” (manufactured by Mitsui Dow Polychemicals), “Sumikasen”, “Sumitate”, “ Aclift", "Excellen" (both manufactured by Sumitomo Chemical Co., Ltd.), "Suntech LD", and "Suntech EVA" (both manufactured by Asahi Kasei Corporation).

Examples of olefinic elastomers used in the layer (A) include ethylene-propylene copolymer elastomers, ethylene-1-butene copolymer elastomers, propylene-1-butene copolymer elastomers, and ethylene-propylene-1-butene copolymer elastomers. Coalescent elastomer, ethylene-1-hexene copolymer elastomer, ethylene-1-octene copolymer elastomer, ethylene-styrene copolymer elastomer, ethylene-norbornene copolymer elastomer, propylene-1-butene copolymer elastomer, ethylene - Olefin-based non-olefin-based elastomers such as propylene-nonconjugated diene copolymer elastomers, ethylene-1-butene-nonconjugated diene copolymer elastomers, and ethylene-propylene-1-butene-nonconjugated diene copolymer elastomers. Typical elastic copolymers, derivatives thereof, acid-modified derivatives and the like can be mentioned.
Specific examples of olefinic elastomers having a crystalline melting peak in the range of 60 to 120° C. include “Milastomer”, “Tafmer” (manufactured by Mitsui Chemicals, Inc.), “ENGAGE”, “INFUSE”, and “AFFINITY”. (above, manufactured by DOW), and the like.
Polypropylene-based resins, polyethylene-based resins, and olefin-based elastomers may be used alone, or may be used in combination. From the viewpoint of adjustment of the crystal melting peak and workability in obtaining a film, it is preferable to combine a plurality of them. When combining more than one, it is more preferable to use one or more olefinic elastomers.

Among the polypropylene-based resins, polyethylene-based resins, and olefin-based elastomers, those having a crystal melting peak of 120° C. or higher as the thermoplastic resin (ii) used for the layer (B) include polypropylene-based resins, polyethylene-based elastomers, From the viewpoint of adjusting the crystal melting peak, it is preferable to use a resin or an olefin-based elastomer.
The polypropylene-based resin used in the layer (B) includes, for example, a homopolymer of propylene (homopolypropylene), a copolymer containing propylene as a main component and other copolymerizable monomers (random polypropylene , block polypropylene), mixtures thereof, and the like.
Polyethylene-based resins used in the layer (B) include high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), and ethylene-based copolymers obtained by polymerization using metallocene-based catalysts (metallocene-based polyethylene). , metal ion crosslinked resins (ionomers) of ethylene-(meth)acrylic acid copolymers, and the like.
Examples of the olefinic elastomer used for the layer (B) include ethylene-propylene copolymer elastomer, ethylene-1-butene copolymer elastomer, propylene-1-butene copolymer elastomer, and ethylene-propylene-1-butene copolymer elastomer. Coalescent elastomer, ethylene-1-hexene copolymer elastomer, ethylene-1-octene copolymer elastomer, ethylene-styrene copolymer elastomer, ethylene-norbornene copolymer elastomer, propylene-1-butene copolymer elastomer, ethylene - Olefin-based non-olefin-based elastomers such as propylene-nonconjugated diene copolymer elastomers, ethylene-1-butene-nonconjugated diene copolymer elastomers, and ethylene-propylene-1-butene-nonconjugated diene copolymer elastomers. Typical elastic copolymers, derivatives thereof, acid-modified derivatives and the like can be mentioned.

Specific examples of polypropylene resins having a crystalline melting peak of 120° C. or higher include “Novatec PP” (manufactured by Japan Polypropylene Corporation), “Sumitomo Noblen” (manufactured by Sumitomo Chemical Co., Ltd.), “PC412A”, “PC630A” and the like. (manufactured by SunAllomer Co., Ltd.), "Prime Polypro" (manufactured by Prime Polymer Co., Ltd.), and the like.
Specific examples of polyethylene resins having a crystalline melting peak of 120° C. or higher include “Novatec HD”, “Novatec LL” (manufactured by Japan Polyethylene Corporation), “Suntech HD” (manufactured by Asahi Kasei Corporation), and “Hi-Zex.” ” (manufactured by Prime Polymer Co., Ltd.) and the like.
Specific examples of olefinic elastomers having a crystalline melting peak of 120° C. or higher include “WELNEX” (manufactured by Japan Polypropylene Corporation), “Xerath” and “TEFABLOCK” (manufactured by Mitsubishi Chemical Corporation).

In each of the resin compositions constituting the layer (A) and the layer (B), the polypropylene-based resin, the polyethylene-based resin, and the olefin-based elastomer may be used alone, or may be used in combination. . From the viewpoint of adjustment of the melting point and processability when obtaining a film, it is preferable to combine a plurality of them. When combining a plurality of resins, it is preferable to use a polypropylene-based resin or a polyethylene-based resin from the viewpoint of adjusting the crystalline melting peak. As the polypropylene-based resin, it is preferable to use random polypropylene or homopolypropylene from the viewpoints of adjustment of the crystalline melting peak, availability, and ease of processing. As the polyethylene-based resin, it is preferable to use high-density polyethylene (HDPE) from the viewpoints of adjustment of the crystalline melting peak, availability, and ease of processing.

The melt flow rates of polypropylene resins, polyethylene resins, olefin elastomers, etc. mentioned above are appropriately selected according to the molding method and application to which they are applied. It is preferable that the value obtained is 0.1 to 50 g/10 minutes. If it is 0.1 g/10 minutes or more, the formability of the film will be good, and if it is 50 g/10 minutes or less, it will be possible to maintain good film thickness accuracy. More preferably 0.5 to 40 g/10 minutes, still more preferably 1.0 to 30 g/10 minutes.

Regarding the strength of polypropylene-based resins, polyethylene-based resins, olefin-based elastomers, etc., it is preferable that the tensile modulus of a film obtained by using these resins alone is in the range of 50 to 2000 MPa. If the tensile modulus is within the range of 50 to 2000 MPa, it is possible to impart appropriate flexibility to the film of the present invention. It is more preferably in the range of 80 to 1900 MPa, still more preferably in the range of 100 to 1800 MPa.
As for the polyolefin-based resin, one type of resin may be used alone, or two or more types may be used in combination. Considering the flexibility, heat resistance, and film formability of the multilayer film to be obtained, it can be appropriately selected as necessary.

A styrene-based elastomer can also be suitably used as the thermoplastic resin (i) used in the layer (A).
By using a styrene-based elastomer, it becomes possible to impart flexibility to the obtained film for back grinding process.

The styrene-based elastomer is preferably a block copolymer represented by the following formula (I) or (II).
X-(Y-X)n ... (I)
(X-Y)n ... (II)
X in general formulas (I) and (II) is an aromatic vinyl polymer block represented by styrene (hereinafter referred to as a styrene component). may be different. Y is butadiene polymer block, isoprene polymer block, butadiene/isoprene copolymer block, hydrogenated butadiene polymer block, hydrogenated isoprene polymer block, hydrogenated butadiene/isoprene copolymer block. It is at least one selected from coalesced blocks, partially hydrogenated butadiene polymer blocks, partially hydrogenated isoprene polymer blocks and partially hydrogenated butadiene/isoprene copolymer blocks. Also, n is an integer of 1 or more.

Specific examples of the styrene elastomer as the thermoplastic resin (i) include styrene-ethylene/butylene-styrene copolymer, styrene-ethylene/propylene-styrene copolymer, and styrene-ethylene/ethylene/propylene-styrene copolymer. coalescence, styrene-butadiene-butene-styrene copolymer, styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer, styrene-hydrogenated butadiene diblock copolymer, styrene-hydrogenated isoprene diblock copolymer polymers, styrene-butadiene diblock copolymers, styrene-isoprene diblock copolymers, among others, styrene-ethylene/butylene-styrene copolymers, styrene-ethylene/propylene-styrene copolymers, styrene - Ethylene/ethylene/propylene-styrene copolymers and styrene-butadiene-butene-styrene copolymers are preferred. A block copolymer, which is a styrene-ethylene/butylene-crystalline olefin copolymer, can also be used.

The content of the styrene component and the content of other components in the styrene elastomer can be measured by using ¹ H-NMR or ¹³ C-NMR. Here, "the content of the styrene component" refers to the content ratio (% by mass) of the aromatic vinyl polymer block represented by styrene based on the mass of the styrene elastomer.

The melt flow rate of the styrene-based elastomer (value measured with a load of 2.16 kg under temperature conditions of 230° C.) is preferably 0.1 to 10 g/10 minutes, more preferably 0.15 to 9 g/10 minutes. is more preferable, and 0.2 to 8 g/10 minutes is particularly preferable.
If the melt flow rate of the styrene elastomer is less than 0.1 g/10 minutes or more than 10 g/10 minutes, the compatibility with the polyolefin resin will decrease and the film-forming properties will deteriorate, resulting in sufficient flexibility and expandability. may not.

Commercially available styrene-based elastomers that can be used as the thermoplastic resin (i) include, for example, "DYNARON DR4600P" (manufactured by JSR Corporation).

As the styrene-based elastomer, one type of elastomer may be used alone, or two or more types may be used in combination. It can be appropriately selected as necessary, taking into account the film formability when obtaining the multilayer film, the flexibility and handleability of the obtained multilayer film, and the expandability.
Moreover, as the thermoplastic resin (i) used for the layer (A), the above styrene-based elastomer and the above-described polyolefin-based resin can be used in combination.

<Other resins>
Either or both of the layer (A) and the layer (B) of the film for back grinding process of the present invention may contain, as resins other than the resins described above, a cyclic olefin-based resin, a polymethylpentene-based resin, a thermoplastic resin (i ), a styrene-based elastomer or the like other than those described in ) can also be added.

As the styrene-based elastomer, in addition to those explained in the section of the thermoplastic resin (i), those having no crystalline melting peak within the range of 60 to 120°C may be added. Addition of the styrene-based elastomer makes it possible to adjust the flexibility of the obtained film for back grinding process.

Examples of cyclic olefin-based resins include norbornene-based polymers, vinyl alicyclic hydrocarbon polymers, and cyclic conjugated diene polymers. Among these, norbornene-based polymers are preferred from the viewpoint of availability and handling. Examples of norbornene-based polymers include ring-opening polymers of norbornene-based monomers, and norbornene-based copolymers obtained by copolymerizing norbornene-based monomers with α-olefins such as ethylene. Hydrogenated products thereof can also be used.

<Other ingredients>
Various additives can be added to each layer of the film for back grinding process of the present invention in order to impart heat resistance, weather resistance, antistatic performance, etc. to the obtained film.
Specific examples include, for example, antistatic agents, antioxidants, neutralizers, lubricants, antiblocking agents, plasticizers, heat stabilizers, light stabilizers, dyes and pigments, crystal nucleating agents, ultraviolet absorbers, fillers, Inorganic fillers that impart rigidity and elastomers other than those mentioned above for imparting flexibility may be used as long as the effects of the present invention are not impaired.
Moreover, when it is necessary to impart different performance to each layer of the film for the back grinding process, various additives can be imparted to each layer.

As the antistatic agent, a known one can be used, but compatibility with the obtained film for back grinding process, imparting long-term antistatic performance, suppression of bleeding out of the antistatic agent over time. From such a viewpoint, it is preferable to use a polymer type antistatic agent.

A known polymeric antistatic agent can be used, and for example, a block copolymer of a hydrophobic block and a hydrophilic block can be used. In the polymer-type antistatic agent, a hydrophobic block and a hydrophilic block form a block copolymer through an ester bond, an ether bond, an amide bond, an imide bond, a urethane bond, a urea bond, or the like.

Hydrophobic blocks include, for example, polyolefin blocks, and polyolefin blocks include blocks made of polyethylene, polypropylene, ethylene-propylene copolymers, and the like.

Hydrophobic blocks such as polyolefin blocks have polar groups such as carbonyl groups, hydroxyl groups and amino groups at both ends. The polar groups that the hydrophobic block has at both ends are polymerized with the carbonyl groups, hydroxyl groups, amino groups, etc. present at both ends of the hydrophilic block, or crosslinked with diisocyanate, diglycidyl ether, etc. Thereby, a block copolymer of a hydrophobic block and a hydrophilic block can be obtained.

Hydrophilic blocks can include, for example, polyether blocks, polyether-containing hydrophilic polymer blocks, cationic polymer blocks and anionic polymer blocks.
In addition, in order to further improve the antistatic properties, the polymer type antistatic agent may contain alkali metal or alkaline earth metal salts, quaternary ammonium salts, surfactants and ions, as long as the effects of the present invention are not impaired. A liquid or the like may be blended.

Examples of commercially available polyether-polyolefin block copolymers, which are one of high-molecular-weight antistatic agents, include Perestat 300, Perestat 230, Pelestat UC, Pelektron PVL, and Pelektron PVH (manufactured by Sanyo Chemical Industries, Ltd.). ) etc. can be mentioned.

As the ultraviolet absorber, known ones can be used, and examples thereof include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and triazine-based ultraviolet absorbers.

As the light stabilizer, a known one can be used, and examples thereof include hindered amine light stabilizers.

Known substances such as organic particles, inorganic particles, and amide compounds can be used as lubricants and antiblocking agents. In addition, since it has excellent compatibility with the above-mentioned polyolefin resin, it is possible to impart defects due to bleeding out to the surface of the obtained film, long-term scratch resistance and slipperiness, so silicone-olefin copolymer is preferably used.

<Film for back grinding process>
The back-grinding process film of the present invention is a back-grinding process film comprising at least two layers including the layer (A) and the layer (B) described above.

Layer (A) is placed on the side of the semiconductor wafer that contacts the side opposite to the side to be polished, while layer (B) is on the side of the film opposite to the side on which layer (A) is provided. must be the outermost layer of the
The film for the back grinding process of the present invention may be a film consisting of two layers, the layer (A) and the layer (B), or may have a layer positioned between the layer (A) and the layer (B). A film having three or more layers may be used.

Here, the layer located in the middle of the film for the back grinding process (hereinafter also referred to as "the layer located in the middle of the film") means a so-called intermediate layer when the film consists of, for example, three layers. When the film consists of four or more layers, not only the middle layer but also the layers before and after it are included in the "layers located in the middle of the film". For example, when the multilayer film consists of four layers, the "layer located in the middle of the film" includes the second and third layers counting from the surface layer, and when the film consists of five layers, In addition to counting the third layer, the second and fourth layers from the surface are also included in the "layer located in the middle of the film".

As a specific configuration of the film for the back grinding process, for example, a two-kind two-layer configuration in which the layer (A) is the surface layer that contacts the semiconductor wafer and the layer (B) is the back layer. ) as the surface layer, the layer (B) as the back layer, and the other layer as the intermediate layer, or a film having a multi-layer structure of more than that. From the viewpoint of ease of film formation and handling of equipment, it is preferable to have a structure of 2 kinds and 2 layers or 3 kinds and 3 layers.

When a layer other than the layer (A) and the layer (B) is provided, it may be the same resin composition as the resin composition constituting the layer (A) and / or the layer (B), or may be different. may From the standpoints of processability of the film, handleability of the obtained film, etc., the resin to be used can be changed to obtain a preferable blend of the resin composition.

In one preferred embodiment of the film for back grinding process of the present invention, the layers other than the layer (A) and the layer (B) have a resin composition different from the resin composition constituting the layer (A) and/or the layer (B). When used as a product, the following configuration can be used.
By including the same resin as the thermoplastic resin used in the layer (A) in the layer in contact with the layer (A), it is possible to improve the adhesion between the layers. Including 5% by mass or more of the thermoplastic resin used in the layer (A) in 100% by mass of the thermoplastic resin used in the layer in contact with the layer (A) improves the adhesion of the resin between the layers. is preferable from the viewpoint of More preferably 10% by mass or more, still more preferably 15% by mass or more.
By including the same resin as the thermoplastic resin used in the layer (B) in the layer in contact with the layer (B), it is possible to improve the adhesion between the layers. Including 5% by mass or more of the thermoplastic resin used in the layer (B) in 100% by mass of the thermoplastic resin used in the layer in contact with the layer (B) improves the adhesion of the resin between the layers. is preferable from the viewpoint of More preferably 10% by mass or more, still more preferably 15% by mass or more.
The layer in contact with the layer (A) and the layer (B) contains the same resin as the thermoplastic resin used in the layer (A) and the layer (B), thereby improving the adhesion between the layers. It becomes possible. 5% by mass or more of each of the thermoplastic resins used in the layers (A) and (B) in 100% by mass of the thermoplastic resins used in the layers in contact with the layers (A) and (B) from the viewpoint of improving the adhesion of the resin between the layers. More preferably each is 10% by mass or more, and still more preferably each is 15% by mass or more.
In addition, when the unevenness of the wafer is large and it is required to follow the unevenness even to the layer located in the middle, the amount added in the layer (A) is larger than the amount necessary to ensure the adhesion between the layers. It is preferable to contain a resin that can be When it is important to maintain the film shape during processing such as bonding to a semiconductor wafer for the intermediate layer, the amount added to the layer (B) is larger than the amount to ensure the above-mentioned adhesion. It is preferable to contain a resin that can be If it is necessary to achieve both conformability to unevenness and retention of the film shape, the amount of each added can be appropriately determined according to the required performance. In any of the above cases, layers other than layer (A) and layer (B) may contain a thermoplastic resin that is not used in layer (A) and layer (B).

Further, the total thickness of the film for back grinding process of the present invention is preferably 30 to 350 μm. If it is 30 μm or more, the film-forming property and the handleability of the obtained film will be good when producing the film, and if it is 350 μm or less, it will be economical and maintain good processability such as adhesive processing using the film. becomes possible.
In addition, from the viewpoint of economy and the handleability of the obtained film for back grinding process, it is more preferably in the range of 40 to 325 μm, and more preferably in the range of 50 to 300 μm.
When the film is attached to the surface of the circuit-formed semiconductor wafer, the thickness of the film can be appropriately selected according to the height of the unevenness of the circuit, and it is preferable that the film is thicker than the unevenness of the wafer. By making the film thicker than the unevenness of the wafer, local thinning of the film when following the wafer does not become remarkable, and even when the film for the back grinding process is peeled from the wafer, the thinned portion does not. It is possible to suppress breakage of the film, which is preferable.

The thickness of layer (A) is preferably in the range of 1 to 20 μm. By having the layer (A) of 1 μm or more, when the back grinding process film is attached to the wafer with the surface of the semiconductor wafer having the circuit and the back grinding process film is peeled off after the wafer is processed, it is possible to remove the film from the wafer. It becomes possible to impart a good releasability. By setting the thickness to 20 μm or less, it becomes possible to adjust the elastic modulus and handleability of the obtained film for a back grinding process. The thickness of the layer (A) can be appropriately determined in consideration of the elastic modulus and handleability of the multilayer film to be obtained and the total thickness described above.

The thickness of layer (B) is preferably in the range of 1 to 20 μm. By having the layer (B) of 1 μm or more, it is possible to impart sufficient heat resistance to the film for the back grinding process, and the film does not completely melt even when heated in the bonding process, etc., and the film shape can be improved. It becomes easier to keep By setting the thickness to 20 μm or less, it becomes possible to adjust the elastic modulus and handleability of the obtained film for a back grinding process. The thickness of the layer (B) can be appropriately determined in consideration of the heat resistance, elastic modulus, handleability, and the above-mentioned total thickness of the multilayer film to be obtained.
In the case of a film having three or more layers provided with a layer located between the layer (A) and the layer (B), the thickness of the layer located in the intermediate layer is the thickness of the layer (A), the layer (B) and the film. It is appropriately determined according to the total thickness.

The tensile modulus of the film for back grinding process of the present invention is preferably in the range of 50 to 1000 MPa. If it is 50 MPa or more, the handleability of the obtained film becomes easy, which is preferable. If it is 1000 MPa or less, the film is given sufficient flexibility and is easy to handle, so that it can be suitably used in the back grinding process. It is more preferably in the range of 70 to 900 MPa, still more preferably in the range of 90 to 800 MPa.
A film for a back grinding process having a tensile modulus of elasticity within the range of 50 to 1000 MPa can be obtained by adjusting the combination of the above-described thermoplastic resins and the like, their addition amount, the ratio of the thickness of each layer of the multilayer film, and the like. becomes possible.
The breaking elongation of the film for back grinding process of the present invention is preferably 500% or more. Having a breaking elongation of 500% or more facilitates peeling from the wafer without breaking the film in the step of peeling the film after processing the wafer. It is more preferably 550% or more, still more preferably 600% or more.

<Method of Forming Film for Backgrinding Process>
As a method for molding the film for the back grinding process of the present invention, a known method can be used, but a melt extrusion molding method is preferably used. Among the melt extrusion molding methods, a T-die molding method in which a molten resin is extruded from an extruder having a T-die and solidified by cooling to obtain a film is more preferable.

In order to obtain a film for the back-grinding process, it is preferable to adopt a co-extrusion T-die molding method using a plurality of extruders. A multi-layered film can be obtained by using a co-extrusion T-die molding method using a plurality of extruders.

As a coextrusion T die molding method, a multi-manifold die is used to form a plurality of resin layers into a film, and then they are brought into contact in the T die to form multiple layers to obtain a film. A method of obtaining a multi-layered film after merging and adhering a plurality of resin compositions using an apparatus for merging the resin compositions.

If necessary, the film for the back grinding process may be surface-treated on one side or both sides by methods such as plasma treatment, corona treatment, ozone treatment and flame treatment. It is possible to select whether to surface-treat one side or both sides depending on the intended use of the resulting film.

<Adhesive layer>
The backgrinding process film of the present invention does not have an adhesive when it is attached to a wafer, and the backgrinding process film can be directly attached to the wafer. Alternatively, an adhesive layer can be laminated on at least one surface for the purpose of adjusting adhesion.

The adhesive used for the adhesive layer is not particularly limited, but various adhesives such as natural rubber resins, acrylic resins, styrene resins, silicone resins, and polyvinyl ether resins are used. Further, a functional layer such as an adhesive layer or a thermosetting resin layer may be provided on the adhesive layer.

In the film for the back grinding process of the present invention, one side or both sides of the film before laminating the adhesive layer may be subjected to the surface treatment described above. A primer layer may be provided between the substrate film and the adhesive layer, if necessary.
The thickness of the adhesive layer and the primer layer can be appropriately determined according to need.

The backgrinding process film of the present invention and the backgrinding process film having an adhesive layer laminated on at least one side thereof can be applied to any wafer such as a silicon wafer, a silicon carbide wafer, a sapphire wafer, or a compound semiconductor wafer. can be used.

Examples and comparative examples of the present invention will be shown and described below in detail, but the present invention is not limited to these examples. The materials used in the following examples and comparative examples, the methods for measuring the properties evaluated, etc. are as follows.

[Materials used]
<Thermoplastic resin (i)>
Olefin-based elastomer (i-1):
Mitsui Chemicals, "Tafmer XM7070" (230 ° C., melt flow rate at 2.16 kg: 7.0 g / 10 minutes, crystalline melting peak: 83 ° C., 1-butene-propylene copolymer)
Olefin-based elastomer (i-2):
Mitsui Chemicals, "Tafmer XM7080" (melt flow rate at 230 ° C., 2.16 kg: 7.0 g / 10 minutes, crystalline melting peak: 75 ° C., 1-butene-propylene copolymer)
Styrene-based elastomer (i-3):
JSR Co., Ltd., "Dynaron DR4600P" (melt flow rate at 230 ° C., 2.16 kg: 5.5 g / 10 minutes, crystal melting peak: 96 ° C., styrene component content: 20% by mass, styrene-ethylene-butylene-crystal olefin copolymer)
Low density polyethylene (i-4):
Japan Polyethylene Co., Ltd., "Novatec LC500" (melt flow rate at 190 ° C., 2.16 kg: 4.0 g / 10 minutes, crystalline melting peak: 106 ° C., tensile modulus of single film: 140 MPa)
Metallocene linear low density polyethylene (i-5):
Ube Maruzen Polyethylene Co., Ltd., "Yumerit 0540F" (190 ° C., melt flow rate at 2.16 kg: 4.0 g / 10 minutes, crystalline melting peaks: 91, 111 ° C., tensile modulus of single film: 80 MPa)

<Thermoplastic resin (ii)>
Random polypropylene (ii-1):
SunAllomer Co., Ltd., "PC630A" (random polypropylene, melt flow rate at 230 ° C., 2.16 kg: 7.5 g / 10 minutes, crystalline melting peak: 135 ° C., tensile modulus of single film: 600 MPa)
Olefin-based elastomer (ii-2):
Japan Polypropylene Corporation, "Wellnex RFX4V" (olefin elastomer, melt flow rate at 230 ° C., 2.16 kg: 6.0 g / 10 minutes, crystalline melting peak: 129 ° C., tensile modulus of single film: 250 MPa)
High density polyethylene (ii-3):
Japan Polyethylene Co., Ltd., "Novatec HF560" (high-density polyethylene, 190 ° C., melt flow rate at 2.16 kg: 7.0 g / 10 minutes, crystalline melting peak: 135 ° C., tensile modulus of single film: 950 MPa)

<Other ingredients>
Antioxidant:
Japan Polyethylene Co., Ltd., "Novatec LL LXAO" (film masterbatch containing 5% by mass of antioxidant)

<Preparation of resin composition>
Either one of the above thermoplastic resin (i) and thermoplastic resin (ii), or both of them were blended so that the total amount was 100 parts by mass, and an antioxidant was added as necessary. When two or more kinds were mixed, they were mixed by dry blending.
It was visually confirmed that the mixture was uniformly mixed, and a resin composition for film molding was prepared for each of the surface layer (layer (A)), the intermediate layer, and the back layer (layer (B)).

<Film forming method>
Each hopper of three single-screw extruders manufactured by Toshiba Machine (for surface layer: 35 φ mm, L / D = 25 mm, for intermediate layer: 50 φ mm, L / D = 32, for back layer: 35 φ mm, L / D = 25 mm) , the extruder temperature of each extruder is set to 180 to 230 ° C., and the surface layer (layer (A)) / intermediate layer / back layer (layer (B)) and extruded from a 650 mm wide T-die (temperature setting: 230° C., lip opening: 0.5 mm). For the thickness configuration, each extruder rotation speed was set so as to achieve the thicknesses shown in Table 1.

The extruded molten resin is cooled and solidified by a winder equipped with a mat-like metal cooling roll (cooling roll width: 700 mm x φ350 mm, roll temperature: about 30°C). Alternatively, a film for back-grinding process having 3 types and 3 layers was obtained.
In the examples and comparative examples, the surface of the obtained film on the side of the mat-like metal cooling roll is referred to as the surface layer (layer (A)).

[Thickness of each layer]
The thickness of each layer was set by calculation from the amount of resin extruded from each extruder.

[Total thickness of film]
Using a contact-type thickness meter, the thickness of the film was measured at the central portion and both ends, and it was confirmed that the film had a predetermined thickness.

[Tensile modulus]
From the resulting multilayer film, a dumbbell "SDK-600" manufactured according to JISK6732 is used to collect a test piece, and with reference to JISK7127, an autograph (Shimadzu The tensile modulus (MPa) was measured at a tensile speed of 50 mm/min using AGS-X manufactured by Seisakusho.
The tensile modulus was measured in the extrusion direction (MD) of the film.

[Tensile breaking elongation]
From the obtained film, a test piece was collected using a dumbbell "SDK-600" manufactured according to JISK6732, and a small desktop tester (EZ-L manufactured by Shimadzu Corporation) was placed in an atmosphere of 23 ° C. and 50% RH. ) was used to measure the tensile elongation at break (%) at a tensile speed of 300 mm/min.
The tensile elongation at break was measured in the extrusion direction (MD) of the film.

[Crystal melting peak]
Using a differential scanning calorimeter (Mettler Toledo DSC823e), about 5 mg of each raw material alone used in Examples and Comparative Examples was heated from 25°C to 230°C at a heating rate of 10°C/min. , the temperature was lowered to 25°C at a cooling rate of 10°C/min, and the temperature was raised again to 230°C at a temperature increase rate of 10°C/min.

[Evaluation of workability by hot plate (layer (A))]
The obtained layer (A) of the film was allowed to stand on a hot plate heated to 110° C. for 5 seconds, and the presence or absence of adhesion of the film to the hot plate was evaluated according to the following criteria.
○: The film melted and adhered to the hot plate. △: The film was deformed and adhered slightly to the hot plate. ×: The film was slightly deformed, or did not adhere to the hot plate without deformation.

[Example 1]
As resins for the surface layer (layer (A)), the intermediate layer, and the back layer (layer (B)), the thermoplastic resin (i), the thermoplastic resin (ii), and the antioxidant described in Table 1 are contained. A film having a thickness of 150 μm consisting of 3 types and 3 layers was obtained by the film-forming method described above. The film forming conditions were adjusted so that the thickness of each layer was 15 μm for the surface layer (layer (A)), 120 μm for the intermediate layer, and 15 μm for the back layer (layer (B)).
The resulting film had a tensile modulus of elasticity of 270 MPa and a tensile elongation at break of 730%, confirming that both the tensile modulus and elongation at break were sufficient for handling the film. Since the breaking elongation was 500% or more, it is possible to peel the film without breaking even when the film is laminated to the thermoplastic resin and the film is peeled after processing such as the back grinding process. it is conceivable that.
Further, the thermoplastic resin (i-1) used in the layer (A) has a crystalline melting peak of 83° C., and since it is a thermoplastic resin having a crystalline melting peak in the range of 60 to 120° C., In the evaluation of workability with a hot plate, it was suggested that the film surface melted and exhibited adhesion, and that it had good workability even at the processing temperature at which the film was bonded to the wafer.
Furthermore, the thermoplastic resin (ii-1) used for the layer (B) has a crystal melting peak of 135° C., and since it is a thermoplastic resin having a crystal melting peak of 120° C. or higher, when bonding to a wafer It was suggested that the layer (B) side does not melt and the film shape can be maintained even at the processing temperature of .
Therefore, it was possible to obtain a thermoplastic resin film whose layer (A) side can be attached to a wafer and which can maintain its film shape even in the processing temperature range.

[Example 2]
As resins for the surface layer (layer (A)), the intermediate layer, and the back layer (layer (B)), the thermoplastic resin (i), the thermoplastic resin (ii), and the antioxidant described in Table 1 are contained. A film having a thickness of 150 μm consisting of 3 types and 3 layers was obtained by the film-forming method described above. The film forming conditions were adjusted so that the thickness of each layer was 15 μm for the surface layer (layer (A)), 120 μm for the intermediate layer, and 15 μm for the back layer (layer (B)).
The resulting film had a tensile modulus of 230 MPa and a tensile elongation at break of 720%, confirming that both the tensile modulus and elongation at break were sufficient for handling the film. Since the breaking elongation was 500% or more, it is possible to peel the film without breaking even when the film is laminated to the thermoplastic resin and the film is peeled after processing such as the back grinding process. it is conceivable that.
The thermoplastic resin (i-2) used in the layer (A) has a crystalline melting peak at 75 ° C., and since it is a thermoplastic resin having a crystalline melting peak in the range of 60 to 120 ° C., it can be used as a hot plate. It was suggested that the film surface melted and exhibited adhesion even in the processability evaluation at , and that the film had good processability even at the processing temperature at which the film was bonded to the wafer.
Furthermore, the thermoplastic resin (ii-1) used for the layer (B) has a crystal melting peak of 135° C., and since it is a thermoplastic resin having a crystal melting peak of 120° C. or higher, when bonding to a wafer It was suggested that the layer (B) side does not melt and the film shape can be maintained even at the processing temperature of .
Therefore, it was possible to obtain a thermoplastic resin film whose layer (A) side can be attached to a wafer and which can maintain its film shape even in the processing temperature range.

[Example 3]
As resins for the surface layer (layer (A)), the intermediate layer, and the back layer (layer (B)), the thermoplastic resin (i), the thermoplastic resin (ii), and the antioxidant described in Table 1 are contained. A film having a thickness of 150 μm consisting of 3 types and 3 layers was obtained by the film-forming method described above. The film forming conditions were adjusted so that the thickness of each layer was 15 μm for the surface layer (layer (A)), 120 μm for the intermediate layer, and 15 μm for the back layer (layer (B)).
The resulting film had a tensile modulus of 230 MPa and a tensile elongation at break of 630%, confirming that both the tensile modulus and elongation at break were sufficient for handling the film. Since the breaking elongation was 500% or more, it is possible to peel the film without breaking even when the film is laminated to the thermoplastic resin and the film is peeled after processing such as the back grinding process. it is conceivable that.
The thermoplastic resin (i-3) used in the layer (A) has a crystalline melting peak of 96 ° C., and since it is a thermoplastic resin having a crystalline melting peak in the range of 60 to 120 ° C., it can be used as a hot plate. It was suggested that the film surface melted and exhibited adhesion even in the processability evaluation at , and that the film had good processability even at the processing temperature at which the film was bonded to the wafer.
Furthermore, the thermoplastic resin (ii-1) used for the layer (B) has a crystal melting peak of 135° C., and since it is a thermoplastic resin having a crystal melting peak of 120° C. or higher, when bonding to a wafer It was suggested that the layer (B) side does not melt and the film shape can be maintained even at the processing temperature of .
Therefore, it was possible to obtain a thermoplastic resin film whose layer (A) side can be attached to a wafer and which can maintain its film shape even in the processing temperature range.

[Example 4]
As resins for the surface layer (layer (A)), the intermediate layer, and the back layer (layer (B)), the thermoplastic resin (i), the thermoplastic resin (ii), and the antioxidant described in Table 1 are contained. A film having a thickness of 150 μm consisting of 3 types and 3 layers was obtained by the film-forming method described above. The film forming conditions were adjusted so that the thickness of each layer was 15 μm for the surface layer (layer (A)), 120 μm for the intermediate layer, and 15 μm for the back layer (layer (B)).
The resulting film had a tensile modulus of 240 MPa and a tensile elongation at break of 750%, confirming that both the tensile modulus and elongation at break were sufficient for handling the film. Since the breaking elongation was 500% or more, it is possible to peel the film without breaking even when the film is laminated to the thermoplastic resin and the film is peeled after processing such as the back grinding process. it is conceivable that.
The thermoplastic resin (i-1) used in the layer (A) has a crystalline melting peak of 83°C, and the thermoplastic resin (i-4) has a crystalline melting peak of 106°C. Since it is a thermoplastic resin having a was done.
Furthermore, the thermoplastic resin (ii-1) used for the layer (B) has a crystal melting peak of 135° C., and since it is a thermoplastic resin having a crystal melting peak of 120° C. or higher, when bonding to a wafer It was suggested that the layer (B) side does not melt and the film shape can be maintained even at the processing temperature of .
Therefore, it was possible to obtain a thermoplastic resin film whose layer (A) side can be attached to a wafer and which can maintain its film shape even in the processing temperature range.

[Example 5]
As resins for the surface layer (layer (A)), the intermediate layer, and the back layer (layer (B)), the thermoplastic resin (i), the thermoplastic resin (ii), and the antioxidant described in Table 1 are contained. A film having a thickness of 150 μm consisting of 3 types and 3 layers was obtained by the film-forming method described above. The film forming conditions were adjusted so that the thickness of each layer was 15 μm for the surface layer (layer (A)), 120 μm for the intermediate layer, and 15 μm for the back layer (layer (B)).
The resulting film had a tensile modulus of elasticity of 240 MPa and a tensile elongation at break of 800%, confirming that both the tensile modulus and elongation at break were sufficient for handling the film. Since the breaking elongation was 500% or more, it is possible to peel the film without breaking even when the film is laminated to the thermoplastic resin and the film is peeled after processing such as the back grinding process. it is conceivable that.
The crystalline melting peak of the thermoplastic resin (i-4) used in the layer (A) is 106°C, and the thermoplastic resin (i-5) is 91°C and 111°C. Since it is a thermoplastic resin with a crystalline melting peak, the film surface melts and exhibits adhesion even when evaluating workability on a hot plate, and it has good workability even at the processing temperature when bonding to a wafer. It has been suggested.
Furthermore, the thermoplastic resin (ii-3) used in the layer (B) has a crystal melting peak of 135° C., and since it is a thermoplastic resin having a crystal melting peak of 120° C. or higher, when bonding to a wafer It was suggested that the layer (B) side does not melt and the film shape can be maintained even at the processing temperature of .
Therefore, it was possible to obtain a thermoplastic resin film whose layer (A) side can be attached to a wafer and which can maintain its film shape even in the processing temperature range.

[Comparative Example 1]
As the resin for the surface layer (layer (A)), the intermediate layer, and the back layer (layer (B)), the thermoplastic resin (ii-1) is used in the content shown in Table 1, and the film-forming method described above is used. A film having a thickness of 150 μm consisting of three layers of one type was obtained. The film forming conditions were adjusted so that the thickness of each layer was 15 μm for the surface layer (layer (A)), 120 μm for the intermediate layer, and 15 μm for the back layer (layer (B)).
The resulting film had a tensile modulus of elasticity of 500 MPa and a tensile elongation at break of 750%, confirming that both the tensile modulus and elongation at break were sufficient for handling the film.
However, the crystalline melting peak of the thermoplastic resin (ii-1) used in the layer (A) is 135 ° C., and it was not a thermoplastic resin having a crystalline melting peak within the range of 60 to 120 ° C. Also in the processability evaluation with a hot plate, the film surface did not melt and did not show adhesion to the hot plate.
Therefore, it was confirmed that the crystal melting peak on the layer (A) side is high, and it is difficult to process in a moderate temperature range when bonding the film to the wafer.

[Comparative Example 2]
As the resin for the surface layer (layer (A)), the intermediate layer, and the back layer (layer (B)), the thermoplastic resin (ii-2) is used in the content shown in Table 1, and the film-forming method described above is used. A film having a thickness of 150 μm consisting of three layers of one type was obtained. The film forming conditions were adjusted so that the thickness of each layer was 15 μm for the surface layer (layer (A)), 120 μm for the intermediate layer, and 15 μm for the back layer (layer (B)).
The resulting film had a tensile modulus of elasticity of 250 MPa and a tensile elongation at break of 680%, confirming that both the tensile modulus and elongation at break were sufficient for handling the film.
However, the crystalline melting peak of the thermoplastic resin (ii-1) used in the layer (A) is 129 ° C., and it was not a thermoplastic resin having a crystalline melting peak within the range of 60 to 120 ° C. Also in the processability evaluation with a hot plate, the film surface did not melt and did not show adhesion to the hot plate.
Therefore, it was confirmed that the crystal melting peak on the layer (A) side is high, and it is difficult to process in a moderate temperature range when bonding the film to the wafer.

[Industrial applicability]
According to the present invention, the workability is excellent when a film is attached to the circuit-bearing surface of a semiconductor wafer or a circuit-formed wafer, and the film for the back grinding process is peeled off from the semiconductor wafer or the circuit-formed wafer. As a result, it is possible to provide a back grinding process film that can be suitably used in the back grinding process.

Claims (6)

A back-grinding process film comprising at least two layers used in a semiconductor wafer polishing process,
It has a layer (A) on the side of the semiconductor wafer that contacts the side opposite to the side to be polished, and the resin composition that constitutes the layer (A) contains crystals within the range of 60 to 120 ° C. containing a thermoplastic resin (i) having a melting peak, and
A thermoplastic resin having a layer (B) as the outermost layer on the film surface opposite to the layer (A), and having a crystalline melting peak of 120° C. or higher in the resin composition constituting the layer (B). (ii) containing
The film for the back grinding process. 2. The film for a back grinding process according to claim 1, wherein the layer (A) is in contact with the circuit-bearing surface of the circuit-bearing semiconductor wafer. 3. The back grinding process film according to claim 1, wherein the thermoplastic resin (i) contained in the layer (A) is one or more selected from the group consisting of polyolefin resins and styrene elastomers. The film for a back grinding process according to any one of claims 1 to 3, wherein the layer (A) has a thickness of 1 to 20 µm, and the total thickness of the layers is 30 to 300 µm. 5. The film for back grinding process according to claim 4, wherein the layer (B) has a thickness of 1 to 20 μm. A film for back grinding process with an adhesive layer, which is obtained by laminating an adhesive layer on one surface of the film for back grinding process according to any one of claims 1 to 5.