Temporary protective film for manufacturing semiconductor device and method for manufacturing semiconductor device

Abstract

A temporary protective film for manufacturing a semiconductor device is provided with: a support film; and an adhesive layer provided on the support film, the adhesive layer containing an acrylic polymer having a weight average molecular weight of 550,000 or more and a molecular weight distribution of 2.0 or less.

Description

TECHNICAL FIELD

[0001] The present application relates to a temporary protective film for semiconductor device manufacturing and a method for manufacturing a semiconductor device. BACKGROUND

[0002] In a semiconductor package, a structure in which a sealing layer is formed only on the semiconductor element side of a lead frame and the back surface of the lead frame is exposed is sometimes adopted. In the manufacturing of a semiconductor package having this structure, it is possible that sealing material overflows to the back surface of the lead frame at the time of forming the sealing layer. In order to prevent this, a method of attaching a temporary protective film to the back surface of the lead frame is known (Patent Literature 1). The temporary protective film is peeled from the lead frame after the sealing layer is formed.

[0003] PRIOR ART DOCUMENTS PATENT LITERATURE Patent Literature 1: International Publication No. 2001 / 035460 SUMMARY

[0004] PROBLEMS TO BE SOLVED BY THE INVENTION In the temporary protective film, it is preferable that, at the time of peeling the temporary protective film from the lead frame after the sealing layer is formed, an adhesive component of the temporary protective film does not remain on the lead frame. Therefore, an object of one aspect of the present application is to provide a temporary protective film in which the remaining on the lead frame at the time of peeling is suppressed.

[0005] MEANS FOR SOLVING THE PROBLEMS According to the research by the present inventors and others, it was ascertained that, by setting the weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) of the acrylic polymer contained in the adhesive layer of the temporary protective film within a specific range, compared with the case of using an acrylic polymer having Mw and Mw / Mn outside the specific range, the generation of remaining on the lead frame is suppressed.

[0006] The present application includes the following aspects.

[0007] [1] A temporary protective film for semiconductor device manufacturing, comprising: a support film; and an adhesive layer provided on the support film, the adhesive layer containing an acrylic polymer, the acrylic polymer having a weight average molecular weight of 550,000 or more and a molecular weight distribution of 2.0 or less.

[0008] [2] The temporary protective film according to [1], wherein the acrylic polymer contains an alkyl (meth)acrylate and a (meth)acryloylmorpholine as monomer units.

[0009] [3] The temporary protective film according to [1] or [2], wherein the weight average molecular weight of the acrylic polymer is 850,000 or more.

[0010] [4] A method for manufacturing a semiconductor device, comprising, in sequence: a step of attaching a temporary protective film to one surface of a substrate; a step of mounting a semiconductor element on a surface of the substrate opposite to the temporary protective film; a step of sealing the semiconductor element; and a step of peeling the temporary protective film off the substrate, wherein the temporary protective film comprises: a support film; and an adhesive layer disposed on the support film, the adhesive layer containing an acrylic polymer having a weight-average molecular weight of 550,000 or more and a molecular weight distribution of 2.0 or less.

[0011] [5] According to the manufacturing method described in [4], the acrylic polymer comprises (meth)acrylate alkyl ester and (meth)acryloylmorpholine as monomer units.

[0012] [6] According to the manufacturing method described in [4] or [5], wherein the weight-average molecular weight of the acrylic polymer is 850,000 or more.

[0013] Invention Effects According to one aspect of the invention, a temporary protective film that can suppress residues on the lead frame during stripping can be provided. Attached Figure Description

[0014] Figure 1 This is a cross-sectional view showing one embodiment of the temporary protective film.

[0015] Figure 2 This is a cross-sectional view illustrating one embodiment of a method for manufacturing a semiconductor device.

[0016] Figure 3 This is a cross-sectional view illustrating one embodiment of a method for manufacturing a semiconductor device.

[0017] Figure 4 This is a cross-sectional view showing one embodiment of a semiconductor device.

[0018] Figure 5 This is a perspective view showing one embodiment of the scroll body. Detailed Implementation

[0019] The embodiments of the present invention will be described below. Figure 1 This is a cross-sectional view showing a temporary protective film according to one embodiment. For example... Figure 1As shown, the temporary protective film 10 according to an embodiment includes a support film 1 and an adhesive layer 2 provided on the support film 1. The temporary protective film 10 can be used as a temporary protective film for semiconductor device manufacturing. More specifically, in a sealing molding process of forming a sealing layer that seals a semiconductor element mounted on a die pad of a lead frame, the temporary protective film 10 can be used as a semiconductor sealing molding temporary protective film for temporarily protecting the lead frame by being attached to the back surface (surface opposite to the surface on which the semiconductor element is mounted) of the lead frame during sealing molding.

[0020] The support film 1 can be, for example, a polymeric film selected from at least one of the group consisting of polyimide, polyamide, polyamide-imide, polysulfone, polyethersulfone, polyphenylene sulfide, polyether ketone, polyarylate, polyether ether ketone, and polyethylene naphthalate, and can be preferably a polyimide film. The polyimide can be an aromatic polyimide. The support film 1 can be a copper, aluminum, stainless steel, or nickel film. In the case where the support film 1 is a polymeric film, the surface thereof can be surface-treated by chemical treatment such as alkali treatment or silane coupling treatment, physical treatment such as sand mat treatment, plasma treatment, and corona treatment.

[0021] The thickness of the support film 1 can be, for example, 5 μm or more, and can be 100 μm or less or 50 μm or less. The ratio T2 / T1 of the thickness T2 of the adhesive layer 2 to the thickness T1 of the support film 1 can be 0.1 or more, and can be 0.5 or less, 0.3 or less, or 0.2 or less.

[0022] The adhesive layer 2 contains an acrylic polymer having a weight average molecular weight (Mw) of 550,000 or more and a molecular weight distribution (Mw / Mn) of 2.0 or less.

[0023] The Mw of the acrylic polymer can be 600,000 or more. Even in the case where the thickness of the adhesive layer 2 is thin (for example, about 2 μm), from the viewpoint of being able to suppress the remaining of the adhesive component on the sealing layer after the temporary protective film is peeled from the lead frame and the sealing layer, the Mw is preferably 650,000 or more, more preferably 750,000 or more, further preferably 850,000 or more, and particularly preferably 950,000 or more. The Mw of the acrylic polymer can be 2,000,000 or less, 1,800,000 or less, 1,600,000 or less, 1,400,000 or less, 1,200,000 or less, or 1,100,000 or less.

[0024] From the viewpoint of being able to further suppress the remaining on the lead frame, the Mw / Mn of the acrylic polymer is preferably 1.9 or less, 1.8 or less, or 1.7 or less. The Mw / Mn of the acrylic polymer can be 1.0 or more, 1.2 or more, 1.4 or more, or 1.6 or more.

[0025] The Mw and the Mw / Mn of the acrylic polymer are measured by the following steps.

[0026] Determined by gel permeation chromatography (GPC) using high-speed liquid chromatography (TOSOH CORPORATION, Model HLC-8320GPC). As the column, two TSKgel Super Multipore HZ-H (TOSOH CORPORATION) were used, tetrahydrofuran solution was used as the mobile phase, and a differential refractometer was used as the detector. The measurement conditions were set to a column temperature of 40°C, a sample concentration of 10 mg / mL, a sample injection amount of 10 μm, and a flow rate of 0.2 mL / min. As the standard substance, polystyrene (molecular weights of 1,090,000, 775,000, 427,000, 289,000, 190,000, 96,400, 37,900, 10,200, 2,630, 440) was used to prepare a calibration curve (correction curve), and the weight average molecular weight (Mw) and the number average molecular weight (Mn) were determined. The molecular weight distribution (Mw / Mn) was calculated from the determined values.

[0027] The acrylic polymer is a polymer containing at least an alkyl (meth)acrylate as a monomer unit, and can be a polymer containing other monomers as monomer units in addition to the alkyl (meth)acrylate.

[0028] The alkyl group (alkyl moiety other than the (meth)acryloyl group) in the alkyl (meth)acrylate can be linear or branched. The number of carbon atoms of the alkyl group can be 2 or more or 3 or more, and can be 30 or less, 20 or less, 10 or less, 7 or less, 5 or less, or 4 or less, or can be 2 or 4.

[0029] As examples of the alkyl (meth)acrylate, there can be mentioned methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, and decyl (meth)acrylate.

[0030] The content of the alkyl (meth)acrylate can be 70% by mass or more, 75% by mass or more, or 80% by mass or more, and can be 92% by mass or less, 90% by mass or less, or 88% by mass or less, based on the total amount of the monomer units in the acrylic polymer.

[0031] From the viewpoint of further suppressing the residue on the lead frame at the time of peeling the temporary protective film, the other monomer preferably contains (meth)acryloylmorpholine. That is, from the same viewpoint, the acrylic polymer preferably contains an alkyl (meth)acrylate and (meth)acryloylmorpholine as monomer units.

[0032] The content of the (meth)acryloyl morpholine can be 7% by mass or more, 7.5% by mass or more, 8% by mass or more, 8.5% by mass or more, or 9.0% by mass or more, and can be 20% by mass or less, 18% by mass or less, 17% by mass or less, 16.5% by mass or less, or 16% by mass or less, based on the total amount of monomer units in the acrylic polymer.

[0033] The mass ratio of the content of the (meth)acryloyl morpholine to the content of the (meth)acrylic acid alkyl ester ((meth)acryloyl morpholine / (meth)acrylic acid alkyl ester) can be 0.08 / 1 or more, 0.09 / 1 or more, or 0.1 / 1 or more, and can be 0.3 / 1 or less, 0.25 / 1 or less, 0.23 / 1 or less, 0.21 / 1 or less, or 0.2 / 1 or less.

[0034] The other monomer can include a monomer having a crosslinkable group (crosslinkable monomer). The crosslinkable monomer has, in addition to the crosslinkable group, a polymerizable group that is copolymerizable with the (meth)acrylic acid alkyl ester and the (meth)acryloyl morpholine. The polymerizable group can be, for example, an ethylenically unsaturated group. The crosslinkable group can be, for example, an acidic group. The acidic group can be, for example, a carboxyl group or a sulfo group, and is preferably a carboxyl group.

[0035] As examples of the crosslinkable monomer having a carboxyl group, (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, phthalic acid monohydroxyethyl acrylate, and 2-acryloyloxyethyl succinate can be given.

[0036] The content of the crosslinkable monomer can be 1% by mass or more, 2% by mass or more, or 3% by mass or more, and can be 10% by mass or less, 6% by mass or less, or 4% by mass or less, based on the total amount of monomer units in the acrylic polymer.

[0037] The other monomer can include, for example, a monomer having a polymerizable group (e.g., an ethylenically unsaturated group) and a hydroxyl group. As examples of the monomer, (meth)acrylic acid hydroxyalkyl esters such as 2-(meth)acrylic acid hydroxyethyl ester, 2-(meth)acrylic acid hydroxypropyl ester, 3-(meth)acrylic acid hydroxypropyl ester, 2-(meth)acrylic acid hydroxybutyl ester, 4-(meth)acrylic acid hydroxybutyl ester, 6-(meth)acrylic acid hydroxyhexyl ester, 8-(meth)acrylic acid hydroxyoctyl ester, 10-(meth)acrylic acid hydroxydecyl ester, 12-(meth)acrylic acid hydroxydodecyl ester, and the like; (meth)acrylic acid hydroxyalkyl cycloalkane esters such as (4-hydroxymethyl cyclohexyl) (meth)acrylate, and the like can be given.

[0038] The acid value of the acrylic polymer can be 10 mgKOH / g or more or 20 mgKOH / g or more, and can be 40 mgKOH / g or less or 30 mgKOH / g or less. The hydroxyl value of the acrylic polymer can be 1 mgKOH / g or more or 2 mgKOH / g or more, and can be 10 mgKOH / g or less or 5 mgKOH / g or less. The acid value and the hydroxyl value of the acrylic polymer are measured according to the method described in JIS K0070.

[0039] The content of the acrylic polymer can be 80 mass% or more, 85 mass% or more, or 90 mass% or more, and can be 99.5 mass% or less or 99 mass% or less, based on the total amount of the adhesive layer 2.

[0040] The adhesive layer 2 can further contain a crosslinking agent, or can not contain a crosslinking agent. The crosslinking agent is a crosslinking agent capable of crosslinking with the crosslinkable group in the acrylic polymer. As such a crosslinking agent, a publicly known crosslinking agent can be used. When the crosslinkable group in the acrylic polymer is an acidic group, the crosslinking agent preferably has an epoxy group. The number of the epoxy groups in the crosslinking agent can be 2 or more or 3 or more, and can be 4 or less, or can be 4.

[0041] In one embodiment, the crosslinking agent can be a crosslinking agent having an amino group in addition to an epoxy group. The amino group can be an amino group in which a hydrogen atom in an -NH2 group is substituted (a substituted amino group), or can be a tertiary amino group. Such a crosslinking agent can have a group represented by the following formula (1).

[0042] The number of the group represented by the above formula (1) in the crosslinking agent can be 1 or 2.

[0043] The crosslinking agent can be a crosslinking agent represented by the following formula (2).

[0044] In the formula, X represents a divalent hydrocarbon group.

[0045] The divalent hydrocarbon group represented by X can be a divalent hydrocarbon group having a ring. The ring can be an alicyclic ring, or can be an aromatic ring. The number of the carbon atoms constituting the ring can be 5 or more, and can be 8 or less, or can be 6. The number of the rings in the divalent hydrocarbon group can be 1 or more, and can be 3 or less, or can be 1 or 2. When a plurality of rings are included in the divalent hydrocarbon group, the plurality of rings can be directly bonded to each other, or can be bonded via an alkylene group having 1 to 3 carbon atoms.

[0046] The divalent hydrocarbon group represented by X preferably has a cycloalkylene group. The number of the carbon atoms of the cycloalkylene group can be 5 or more, and can be 8 or less. The cycloalkylene group is preferably a cyclohexylene group.

[0047] In one embodiment, the crosslinking agent can be a crosslinking agent having an ether group (not having an amino group) in addition to an epoxy group. This crosslinking agent can have a group represented by the following formula (3).

[0048] The number of the group represented by the above formula (3) in the crosslinking agent can be 2 or more or 3 or more, and can be 4 or less, or 2 or 4.

[0049] The crosslinking agent can be a crosslinking agent represented by the following formula (4).

[0050] In the formula, m represents an integer of 2 or more, n represents an integer of 0 or more, and A represents a residue obtained by removing a hydroxyl group from a (m+n)-valent polyol.

[0051] M can be an integer of 3 or more, an integer of 4 or less, or 2 or 4. N can be an integer of 1 or more, an integer of 2 or less, or 0 or 2. M + n can be an integer of 2 or more, an integer of 6 or less.

[0052] The polyol in A can be an aliphatic polyol or an alicyclic polyol, or a polyol having an ether group. The aliphatic polyol or the alicyclic polyol can have a number of carbon atoms of 2 or more, 3 or more, or 4 or more, and can have a number of carbon atoms of 10 or less, 9 or less, or 8 or less. The polyol having an ether group can be a polyalkylene glycol such as polyethylene glycol.

[0053] The content of the crosslinking agent can be 0.5% by mass or more, and can be 15% by mass or less or 10% by mass or less, based on the total amount of the adhesive layer 2, and is preferably 1% by mass or more, 2% by mass or more, or 2.5% by mass or more from the viewpoint of suppressing deterioration in the appearance of the adherend after the temporary protective film is peeled from the adherend.

[0054] The content of the crosslinking agent can be 0.5 parts by mass or more, and can be 15 parts by mass or less or 10 parts by mass or less, with respect to 100 parts by mass of the content of the acrylic polymer, and is preferably 1 part by mass or more, 2 parts by mass or more, or 3 parts by mass or more from the viewpoint of suppressing deterioration in the appearance of the adherend after the temporary protective film is peeled from the adherend.

[0055] The adhesive layer 2 can further contain other components in addition to the acrylic polymer and the crosslinking agent. As examples of the other components, a polymer other than the acrylic polymer and a coupling agent can be given.

[0056] The thickness of the adhesive layer 2 can be 1 μm or more, or 2 μm or more, and can be 20 μm or less, 15 μm or less, 10 μm or less, 5 μm or less, 4 μm or less, or 3 μm or less.

[0057] In another embodiment, the temporary protective film can further have a cover film provided on the surface of the adhesive layer opposite the support film. That is, the temporary protective film can have, in order, the support film, the adhesive layer, and the cover film. The cover film can be a polyethylene terephthalate film. The thickness of the cover film can be 10 μm or more, and can be 100 μm or less.

[0058] In another embodiment, the temporary protective film can further have a non-adhesive layer provided on the support film opposite the adhesive layer. The non-adhesive layer can be a resin layer that has substantially no adhesiveness to an adherend at 0 to 270°C. The non-adhesive layer can include a thermoplastic resin, a thermosetting resin (cured product), or a combined resin thereof. The non-adhesive layer can further contain a filler (for example, ceramic powder, glass powder, silver powder, copper powder, resin particles, rubber particles), a coupling agent, or the like. The thickness of the non-adhesive layer can be 1 μm or more, and can be 10 μm or less.

[0059] The temporary protective film can be manufactured, for example, by a method including a step of forming the adhesive layer by applying a varnish including an acrylic polymer and a crosslinking agent on the support film, and removing a solvent from the coated film.

[0060] Next, a method for manufacturing a semiconductor device using the above-described temporary protective film will be described. The method for manufacturing a semiconductor device of one embodiment includes, in order, a step S1 of attaching the temporary protective film to one surface side of a substrate, a step S2 of mounting a semiconductor element on the surface of the substrate opposite the temporary protective film, a step S3 of sealing the semiconductor element, and a step S4 of peeling the temporary protective film from the substrate. Hereinafter, the method for manufacturing a semiconductor device (semiconductor device package) will be described more specifically in the case where the substrate is a lead frame, as an example.

[0061] Figure 2 is a cross-sectional view illustrating one embodiment of a method for manufacturing a semiconductor device (step S1). In the step S1, as shown in FIG. 1A, the temporary protective film 10 is attached to one surface, i.e., the back surface, of the lead frame 11 having a chip pad 11a and an internal lead 11b. The temporary protective film 10 is attached in a direction in which the adhesive layer of the temporary protective film 10 is in contact with the lead frame 11. Figure 2

[0062] The lead frame 11 can be formed of, for example, an iron-based alloy such as 42 alloy, copper, or a copper-based alloy. The lead frame 11 can have a shaped body formed of copper or a copper-based alloy, and a cladding layer of palladium, gold, silver, or the like covering the surface thereof.

[0063] ​The temporary protective film 10 has excellent adhesion at normal temperature (e.g., 25°C), and thus can be attached to the lead frame 11 at normal temperature. The temporary protective film 10 can be attached to the lead frame 11 while being heated and pressurized. In this case, the heating temperature can be 150°C or higher and 400°C or lower. The pressure can be 0.5 MPa or higher and 30 MPa or lower. The heating and pressurizing time can be 1 second or longer and 60 seconds or shorter.

[0064] Figure 3 is a sectional view illustrating an embodiment of a method of manufacturing a semiconductor device (process S2 and process S3). In process S2, as shown in Figure 3 , a semiconductor element 14 is mounted on the surface of the chip pad 11a on the side opposite the temporary protective film 10. The semiconductor element 14 is adhered to the chip pad 11a via an adhesive (e.g., silver paste). After the semiconductor element 14 is adhered to the chip pad 11a, reflow soldering (CuClip connection or the like) can be performed at a temperature of 250 to 440°C or 250 to 400°C and for 1 to 30 minutes.

[0065] Next, the semiconductor element 14 is connected to the inner lead 11b using a wire 12. The wire 12 can be, for example, a gold wire, a copper wire, or a palladium-coated copper wire. The wire 12 can be bonded to the semiconductor element 14 and the inner lead 11b using ultrasonic waves and press-fit pressure while being heated at 200 to 350°C, for example.

[0066] Next, in process S3, as shown in Figure 3 , a sealing layer 13 that seals the semiconductor element 14 and the wire 12 is formed. Thus, a temporarily-protected sealing molded body 20 having the lead frame 11, the semiconductor element 14, and the sealing layer 13 is obtained.

[0067] The sealing layer 13 is formed by sealing molding using a sealing material. By sealing molding, a sealing molded body 20 having a plurality of semiconductor elements 14 and a sealing layer 13 that seals them together can be obtained. During sealing molding, by providing the temporary protective film 10, overflow of the sealing material to the back surface side of the lead frame 11 is suppressed.

[0068] The temperature during formation of the sealing layer 13 (temperature of the sealing material) can be 140 to 200°C or 160 to 180°C. The pressure during formation of the sealing layer can be 6 to 15 MPa or 7 to 10 MPa. The time of sealing molding can be 1 to 5 minutes or 2 to 3 minutes.

[0069] The sealing material can contain, for example, an epoxy resin such as a cresol novolac epoxy resin, a phenol novolac epoxy resin, a biphenyl diepoxy resin, a naphthol novolac epoxy resin, or the like. The sealing material can contain a filler, a flame retardant substance such as a bromine compound, a wax component, or the like.

[0070] After the sealing layer 13 is formed (sealing molding), the temporary protective film 10 is peeled off from the lead frame 11 and the sealing layer 13 of the obtained sealing molded body 20. In the case where the sealing layer 13 is cured, the temporary protective film 10 can be peeled off at any point in time before or after the curing of the sealing layer 13.

[0071] The temperature at which the temporary protective film 10 is peeled off is not particularly limited, and can be room temperature (e.g., 5 to 35°C) or the glass transition temperature (Tg) of the adhesive layer or more. In this case, the temporary protective film 10 can be further favorably peeled off from the lead frame 11 and the sealing material. If the Tg of the acrylic polymer in the adhesive layer is, for example, 5°C or less or 0°C or less, the Tg of the adhesive layer becomes the same degree or less as room temperature, and the temporary protective film is easily favorably peeled off at room temperature.

[0072] In the case where the lead frame 11 has a plurality of patterns including the chip pad 11a and the inner lead 11b, the sealing molded body 20 is divided as necessary, and a plurality of semiconductor devices (semiconductor packages) 100 each having one semiconductor element can be obtained. Figure 4 In the case where the lead frame 11 has a plurality of chip pads 11a and a semiconductor element 14 is mounted on each of the plurality of chip pads 11a, the manufacturing method according to an embodiment can further include a step of dividing the sealing molded body 20 after the temporary protective film 10 is peeled off from the sealing molded body 20, thereby obtaining a semiconductor device (semiconductor package) 100 having one chip pad 11a and one semiconductor element 14.

[0073] The temporary protective film is in a long strip shape, and can be used in a state of being wound around a winding core of a reel body. In this case, the temporary protective film is attached to the adherend while being unwound from the reel body.

[0074] Figure 5 is a perspective view showing one embodiment of a reel body. As shown in Figure 5 The reel body 30 according to an embodiment includes a winding core 31, a temporary protective film 10 wound around the winding core 31, and a side plate 32. The width (length in a direction orthogonal to the winding direction) of the winding core 31 and the temporary protective film 10 can be 1 mm or more, 5 mm or more, or 10 mm or more, and can be 1000 mm or less, 800 mm or less, or 500 mm or less. In another embodiment, the reel body can not include the side plate.

[0075] Example Hereinafter, the present application will be described more specifically by citing examples. However, the present application is not limited to the examples.

[0076] (Example 1) A clear coat for forming an adhesive layer was obtained by dissolving an acrylic polymer A-1 having a weight average molecular weight (Mw) of 600,000 and a molecular weight distribution (Mw / Mn) of 1.7 in cyclohexanone. The acrylic polymer A-1 was a copolymer of butyl acrylate / acryloylmorpholine / acrylic acid / other monomer (monomer having a hydroxyl group) = 80 / 16 / 3 / 1 (mass ratio). As a support film, a polyimide film (thickness: 25 μm, manufactured by DU PONT-TORAY CO., LTD., trade name: Kapton 100EN) was prepared. The obtained clear coat was applied to one side of the support film. The coating film on the support film was dried by heating at 90°C for 1.5 minutes and at 260°C for 1.5 minutes, and an adhesive layer having a thickness of 2 μm was formed. Thus, a temporary protective film was obtained.

[0077] (Examples 2 to 3) The thickness of the adhesive layer was changed as shown in Table 1, and otherwise, a temporary protective film was obtained in the same manner as in Example 1.

[0078] (Example 4) A clear coat was prepared by adding 10 parts by mass of a crosslinking agent B-1 represented by the following formula (B-1) to 100 parts by mass of the acrylic polymer A-1, and the thickness of the adhesive layer was changed as shown in Table 1, and otherwise, a temporary protective film was obtained in the same manner as in Example 1. A clear coat was prepared by adding 10 parts by mass of a crosslinking agent B-1 represented by the following formula (B-1) to 100 parts by mass of the acrylic polymer A-1, and the thickness of the adhesive layer was changed as shown in Table 1, and otherwise, a temporary protective film was obtained in the same manner as in Example 1.

[0079] (Example 5) Instead of 10 parts by mass of the crosslinking agent B-1, 7 parts by mass of a crosslinking agent B-2 represented by the following formula (B-2) was used, and otherwise, a temporary protective film was obtained in the same manner as in Example 4. Instead of 10 parts by mass of the crosslinking agent B-1, 7 parts by mass of a crosslinking agent B-2 represented by the following formula (B-2) was used, and otherwise, a temporary protective film was obtained in the same manner as in Example 4.

[0080] (Example 6) Instead of the acrylic polymer A-1, an acrylic polymer A-2 having a weight average molecular weight (Mw) of 1,000,000 and a molecular weight distribution (Mw / Mn) of 1.9 was used, and otherwise, a temporary protective film was obtained in the same manner as in Example 1. The acrylic polymer A-2 was a copolymer of butyl acrylate / acryloylmorpholine / acrylic acid / other monomer (monomer having a hydroxyl group) = 80 / 16 / 3 / 1 (mass ratio).

[0081] (Examples 7 to 8) The thickness of the adhesive layer was changed as shown in Table 1, and otherwise, a temporary protective film was obtained in the same manner as in Example 6.

[0082] (Comparative Example 1) Instead of 100 parts by mass of the acrylic polymer A-1, a varnish was prepared using 100 parts by mass of an acrylic polymer a-1 (trade name: HTR-280, manufactured by Nagase Chemtex Corporation) having a weight average molecular weight (Mw) of 990,000 and a molecular weight distribution (Mw / Mn) of 3.0, and 30 parts by mass of a crosslinking agent B-3 represented by the following formula (B-3): A temporary protection film was obtained in the same manner as in Example 1, except that the thickness of the adhesive layer was changed as shown in Table 1, and a varnish was prepared using 30 parts by mass of the acrylic polymer a-1, 70 parts by mass of an acrylic polymer a-2 (trade name: WS-023 EK30, manufactured by Nagase Chemtex Corporation) having a weight average molecular weight (Mw) of 720,000 and a molecular weight distribution (Mw / Mn) of 4.4, and 10 parts by mass of the crosslinking agent B-3 instead of 100 parts by mass of the acrylic polymer A-1.

[0083] (Comparative Example 2) A temporary protection film was obtained in the same manner as in Example 1, except that the thickness of the adhesive layer was changed as shown in Table 1, and a varnish was prepared using 30 parts by mass of the acrylic polymer a-1, 70 parts by mass of an acrylic polymer a-2 (trade name: WS-023 EK30, manufactured by Nagase Chemtex Corporation) having a weight average molecular weight (Mw) of 720,000 and a molecular weight distribution (Mw / Mn) of 4.4, and 10 parts by mass of the crosslinking agent B-3 instead of 100 parts by mass of the acrylic polymer A-1.

[0084] (Evaluation of Residue) Each of the temporary protection films was attached to a CDA194 palladium-plated Cu plate (lead frame, manufactured by Shinko Electric Industries Co., Ltd.) with the adhesive layer in contact with the lead frame under a 20N load at 25°C. The obtained laminate was heated in an oven under an air atmosphere, and the conditions were changed in the order of heating at 180°C for 60 minutes and then at 200°C for 60 minutes. The surface of the lead frame on the opposite side to the temporary protection film was subjected to plasma treatment under an argon atmosphere (flow rate: 20 seem), at 150W for 15 seconds.

[0085] A mold forming machine (manufactured by APIC YAMADA CORPORATION) was used to form a sealing layer on the surface of the lead frame on the side opposite the temporary protective film by a sealing material (trade name: GE-300, manufactured by Showa Denko Materials co., Ltd.). The sealing conditions were set to 175°C, 6.8 MPa, and 2 minutes. Thereafter, at 25°C, the temporary protective film was peeled off in a direction at 180° with respect to the surface of the lead frame at a speed of 50 mm / minute. The state of the adhesive layer remaining on the lead frame and the sealing layer, respectively, after peeling off the temporary protective film was confirmed. The proportion of the area of the remaining adhesive layer to the area of the surface of the lead frame and the proportion of the area of the remaining adhesive layer to the area of the surface of the sealing layer were calculated. According to the proportion of the area of the remaining adhesive layer, evaluation was performed according to the following criteria. The results are shown in Table 1.

[0086] A: Less than 5% B: 5% or more but less than 15% C: 15% or more [Table 1]

[0087] Explanation of Symbols 1 - support film, 2 - adhesive layer, 10 - temporary protective film, 11 - lead frame, 11a - chip pad, 11b - inner lead, 12 - lead wire, 13 - sealing layer, 14 - semiconductor element, 20 - sealing formed body, 100 - semiconductor device.

Claims

1. A temporary protective film for semiconductor device production, comprising: a support film; and a pressure-sensitive adhesive layer provided on the support film, the pressure-sensitive adhesive layer containing an acrylic polymer having a weight average molecular weight of 550,000 or more and a molecular weight distribution of 2.0 or less.

2. The temporary protective film according to claim 1, wherein the acrylic polymer contains an alkyl (meth)acrylate and a (meth)acryloylmorpholine as monomer units.

3. The temporary protective film according to claim 1 or 2, wherein the weight average molecular weight of the acrylic polymer is 850,000 or more.

4. A method for producing a semiconductor device, comprising, in this order: a step of attaching a temporary protective film to one surface side of a substrate; a step of mounting a semiconductor element on a surface of the substrate opposite to the temporary protective film; a step of sealing the semiconductor element; and a step of peeling the temporary protective film from the substrate, the temporary protective film comprising: a support film; and a pressure-sensitive adhesive layer provided on the support film, the pressure-sensitive adhesive layer containing an acrylic polymer having a weight average molecular weight of 550,000 or more and a molecular weight distribution of 2.0 or less.

5. The production method according to claim 4, wherein the acrylic polymer contains an alkyl (meth)acrylate and a (meth)acryloylmorpholine as monomer units.

6. The production method according to claim 4 or 5, wherein the weight average molecular weight of the acrylic polymer is 850,000 or more. ​ ​ ​ ​ ​ ​ ​ wherein ​ ​ ​ ​ ​ ​ ​ ​

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