Temporary protection film for semiconductor device production and semiconductor device production method

Abstract

This temporary protective film for semiconductor device production comprises a support film and an adhesive layer provided on the support film. The adhesive layer contains 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

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

[0001] The present disclosure relates to a temporary protective film for use in manufacturing a semiconductor device and a method for manufacturing a semiconductor device.

[0002] Semiconductor packages often have a structure in which an encapsulating layer is formed only on the semiconductor element side of the lead frame, leaving the back surface of the lead frame exposed. In manufacturing semiconductor packages with this structure, there is a risk that the encapsulating material will get onto the back surface of the lead frame when the encapsulating layer is formed. To prevent this, a method is known in which a temporary protective film is attached to the back surface of the lead frame (see Patent Document 1). The temporary protective film is peeled off from the lead frame after the encapsulating layer is formed.

[0003] WO 2001 / 035460

[0004] In the temporary protective film, it is desirable that the adhesive component of the temporary protective film does not remain on the lead frame when the temporary protective film is peeled off from the lead frame after the sealing layer is formed. Therefore, one aspect of the present invention aims to provide a temporary protective film that can suppress the adhesive component from remaining on the lead frame when peeled off.

[0005] According to the inventors' investigations, it has been found that by setting the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the acrylic polymer contained in the adhesive layer of the temporary protective film within a specific range, the occurrence of residues on the lead frame can be suppressed compared to when an acrylic polymer having an Mw and Mw / Mn outside the specific range is used.

[0006] The present invention includes the following aspects. [1] A temporary protective film for use in semiconductor device production, comprising a support film and an adhesive layer provided on the support film, wherein the adhesive layer contains 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 [1], wherein the acrylic polymer contains alkyl (meth)acrylate and (meth)acryloyl morpholine as monomer units. [3] The temporary protective film according to [1] or [2], wherein the acrylic polymer has a weight-average molecular weight of 850,000 or more. [4] A method for producing a semiconductor device, comprising, in this order, the steps of attaching a temporary protective film to one side of a substrate, mounting a semiconductor element on the side of the substrate opposite the temporary protective film, encapsulating the semiconductor element, and peeling the temporary protective film from the substrate, wherein the temporary protective film comprises a support film and an adhesive layer provided on the support film, wherein the adhesive layer contains 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 method according to [4], wherein the acrylic polymer contains alkyl (meth)acrylate and (meth)acryloyl morpholine as monomer units. [6] The method according to [4] or [5], wherein the weight average molecular weight of the acrylic polymer is 850,000 or more.

[0007] According to one aspect of the present invention, it is possible to provide a temporary protective film that can be prevented from remaining on a lead frame when peeled off.

[0008] Fig. 1 is a cross-sectional view showing an embodiment of a temporary protective film; Fig. 2 is a cross-sectional view illustrating an embodiment of a method for manufacturing a semiconductor device; Fig. 3 is a cross-sectional view illustrating an embodiment of a method for manufacturing a semiconductor device; Fig. 4 is a cross-sectional view showing an embodiment of a semiconductor device; Fig. 5 is a perspective view showing an embodiment of a reel body;

[0009] Hereinafter, an embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing a temporary protective film according to one embodiment. As shown in FIG. 1, a temporary protective film 10 according to one 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 manufacturing a semiconductor device. More specifically, the temporary protective film 10 can be attached to the back surface of a lead frame (the surface opposite to the surface on which the semiconductor element is mounted) during the encapsulation molding process to form an encapsulation layer that encapsulates a semiconductor element mounted on a die pad of the lead frame, thereby being used as a temporary protective film for semiconductor encapsulation molding to temporarily protect the lead frame during encapsulation molding.

[0010] The support film 1 may be, for example, a film of at least one polymer selected from the group consisting of polyimide, polyamide, polyamideimide, polysulfone, polyethersulfone, polyphenylene sulfide, polyetherketone, polyarylate, polyetheretherketone, and polyethylene naphthalate, and is preferably a polyimide film. The polyimide may be an aromatic polyimide. The support film 1 may also be a film of copper, aluminum, stainless steel, or nickel. When the support film 1 is a polymer film, its surface may be surface-treated by a method such as a chemical treatment, an alkali treatment, a silane coupling treatment, or the like, a physical treatment, such as a sand mat treatment, a plasma treatment, or a corona treatment.

[0011] The thickness of the support film 1 may be, for example, 5 μm or more, 100 μm or less, or 50 μm or less. １ Thickness T of adhesive layer 2 ２ The ratio T ２ / T １ may be 0.1 or more, and may be 0.5 or less, 0.3 or less, or 0.2 or less.

[0012] 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.

[0013] The Mw of the acrylic polymer may be 600,000 or more, and is preferably 650,000 or more, more preferably 750,000 or more, even more preferably 850,000 or more, and particularly preferably 950,000 or more, from the viewpoint of suppressing the adhesive component from remaining on the sealing layer after peeling the temporary protective film from the lead frame and the sealing layer, even when the thickness of the adhesive layer 2 is thin (for example, about 2 μm). The Mw of the acrylic polymer may 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.

[0014] From the viewpoint of further suppressing residue on the lead frame, the Mw / Mn of the acrylic polymer may be preferably 1.9 or less, 1.8 or less, or 1.7 or less, or 1.0 or more, 1.2 or more, 1.4 or more, or 1.6 or more.

[0015] The Mw and Mw / Mn of an acrylic polymer are measured by the following procedure. They were determined by gel permeation chromatography (GPC) using a high-performance liquid chromatograph (Tosoh Corporation, Model HLC-8320GPC). Two TSKgel Super Multipore HZ-H (Tosoh Corporation) columns were used, a tetrahydrofuran solution was used as the mobile phase, and a differential refractometer was used as the detector. The measurement conditions were a column temperature of 40°C, a sample concentration of 10 mg / mL, a sample injection volume of 10 μm, and a flow rate of 0.2 mL / min. A calibration curve was created using polystyrene (molecular weights: 1,090,000, 775,000, 427,000, 289,000, 190,000, 96,400, 37,900, 10,200, 2,630, and 440) as a standard substance, and the weight-average molecular weight (Mw) and number-average molecular weight (Mn) were measured. The molecular weight distribution (Mw / Mn) was calculated from these measurements.

[0016] The acrylic polymer is a polymer containing at least alkyl (meth)acrylate as a monomer unit, and may be a polymer containing other monomers as monomer units in addition to alkyl (meth)acrylate.

[0017] The alkyl group in the alkyl(meth)acrylate (the alkyl group portion other than the (meth)acryloyl group) may be linear or branched. The number of carbon atoms in the alkyl group may be 2 or more or 3 or more, and may be 30 or less, 20 or less, 10 or less, 7 or less, 5 or less, or 4 or less, or may be 2 or 4.

[0018] Examples of alkyl (meth)acrylates include 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.

[0019] The content of alkyl (meth)acrylate may be 70% by mass or more, 75% by mass or more, or 80% by mass or more, and may be 92% by mass or less, 90% by mass or less, or 88% by mass or less, based on the total amount of monomer units in the acrylic polymer.

[0020] The other monomers preferably include (meth)acryloylmorpholine from the viewpoint of further suppressing the temporary protective film from remaining on the lead frame when peeled off, i.e., from the same viewpoint, the acrylic polymer preferably includes alkyl(meth)acrylate and (meth)acryloylmorpholine as monomer units.

[0021] The content of (meth)acryloylmorpholine may 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, based on the total amount of monomer units in the acrylic polymer, and may 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.

[0022] The mass ratio of the (meth)acryloylmorpholine content to the alkyl(meth)acrylate content ((meth)acryloylmorpholine / alkyl(meth)acrylate) may be 0.08 / 1 or more, 0.09 / 1 or more, or 0.1 / 1 or more, and may 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.

[0023] The other monomers may include a monomer having a crosslinkable group (crosslinkable monomer). The crosslinkable monomer has, in addition to the crosslinkable group, a polymerizable group copolymerizable with alkyl (meth)acrylate and (meth)acryloylmorpholine. The polymerizable group may be, for example, an ethylenically unsaturated group. The crosslinkable group may be, for example, an acidic group. The acidic group may be, for example, a carboxyl group or a sulfo group, and is preferably a carboxyl group.

[0024] Examples of crosslinkable monomers having a carboxyl group include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, monohydroxyethyl phthalate acrylate, and 2-acryloyloxyethyl succinate.

[0025] The content of the crosslinkable monomer may be 1% by mass or more, 2% by mass or more, or 3% by mass or more, and may 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.

[0026] The other monomer may include, for example, a monomer having a polymerizable group (e.g., an ethylenically unsaturated group) and a hydroxyl group. Examples of this monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate; and hydroxyalkyl cycloalkane (meth)acrylates such as (4-hydroxymethylcyclohexyl)methyl (meth)acrylate.

[0027] The acid value of the acrylic polymer may be 10 mgKOH / g or more or 20 mgKOH / g or more, and 40 mgKOH / g or less or 30 mgKOH / g or less. The hydroxyl value of the acrylic polymer may be 1 mgKOH / g or more or 2 mgKOH / g or more, and 10 mgKOH / g or less or 5 mgKOH / g or less. The acid value and hydroxyl value of the acrylic polymer are measured in accordance with the method described in JIS K0070.

[0028] The content of the acrylic polymer may be 80% by mass or more, 85% by mass or more, or 90% by mass or more, and may be 99.5% by mass or less, or 99% by mass or less, based on the total amount of the adhesive layer 2.

[0029] The adhesive layer 2 may further contain a crosslinking agent, or may not contain a crosslinking agent. The crosslinking agent is a crosslinking agent that can crosslink with the crosslinkable group in the acrylic polymer. As such a crosslinking agent, a 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 epoxy groups in the crosslinking agent may be 2 or more, 3 or more, or 4 or less, or may be 4.

[0030] In one embodiment, the crosslinking agent may be a crosslinking agent having an amino group in addition to an epoxy group. ２The crosslinking agent may have a group represented by the following formula (1): The number of groups represented by the above formula (1) in the crosslinking agent may be one or two.

[0031] The crosslinking agent may be a crosslinking agent represented by the following formula (2): In the formula, X represents a divalent hydrocarbon group.

[0032] The divalent hydrocarbon group represented by X may be a divalent hydrocarbon group having a ring. The ring may be an alicyclic ring or an aromatic ring. The number of carbon atoms constituting the ring may be 5 or more, 8 or less, or 6. The number of rings in the divalent hydrocarbon group may be 1 or more, 3 or less, or 1 or 2. When the divalent hydrocarbon group contains multiple rings, the multiple rings may be bonded to each other directly or via an alkylene group having 1 to 3 carbon atoms.

[0033] The divalent hydrocarbon group represented by X preferably has a cycloalkylene group. The number of carbon atoms in the cycloalkylene group may be 5 or more and 8 or less. The cycloalkylene group is preferably a cyclohexylene group.

[0034] In one embodiment, the crosslinking agent may be a crosslinking agent having an ether group (without an amino group) in addition to an epoxy group. Such a crosslinking agent may have a group represented by the following formula (3):

[0035] The number of groups represented by the above formula (3) in the crosslinking agent may be 2 or more, 3 or more, or 4 or less, or may be 2 or 4.

[0036] The crosslinking agent may be a crosslinking agent represented by the following formula (4): 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 an (m+n)-valent polyhydric alcohol.

[0037] m may be an integer of 3 or greater, an integer of 4 or less, or may be 2 or 4. n may be an integer of 1 or greater, an integer of 2 or less, or may be 0 or 2. m+n may be an integer of 2 or greater, or may be an integer of 6 or less.

[0038] The polyhydric alcohol in A may be an aliphatic polyhydric alcohol or an alicyclic polyhydric alcohol, or may be a polyhydric alcohol having an ether group. The number of carbon atoms in the aliphatic polyhydric alcohol or alicyclic polyhydric alcohol may be 2 or more, 3 or more, or 4 or more, and may be 10 or less, 9 or less, or 8 or less. The polyhydric alcohol having an ether group may be a polyalkylene glycol such as polyethylene glycol.

[0039] The content of the crosslinking agent may be 0.5 mass% or more, 15 mass% or less, or 10 mass% or less, based on the total amount of the adhesive layer 2, and is preferably 1 mass% or more, 2 mass% or more, or 2.5 mass% or more, from the viewpoint of preventing the appearance of the adherend from deteriorating after the temporary protective film is peeled off from the adherend.

[0040] The content of the crosslinking agent may be 0.5 parts by mass or more, 15 parts by mass or less, or 10 parts by mass or less, relative to 100 parts by mass of the acrylic polymer content, 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 preventing the appearance of the adherend from deteriorating after the temporary protective film is peeled off from the adherend.

[0041] The adhesive layer 2 may further contain other components in addition to the acrylic polymer and the crosslinking agent. Examples of the other components include a polymer other than the acrylic polymer and a coupling agent.

[0042] The thickness of the adhesive layer 2 may be 1 μm or more, or 2 μm or more, and may 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.

[0043] In another embodiment, the temporary protective film may further include a cover film provided on the surface of the adhesive layer opposite the support film. That is, the temporary protective film may include a support film, an adhesive layer, and a cover film in this order. The cover film may be a polyethylene terephthalate film. The thickness of the cover film may be 10 μm or more and 100 μm or less.

[0044] In another embodiment, the temporary protective film may further include a non-adhesive layer provided on the side of the support film opposite the adhesive layer. The non-adhesive layer may be a resin layer that has substantially no adhesiveness to an adherend at 0 to 270°C. The non-adhesive layer may contain a thermoplastic resin, a thermosetting resin (cured product), or a resin that is a combination thereof. The non-adhesive layer may further contain a filler (e.g., ceramic powder, glass powder, silver powder, copper powder, resin particles, rubber particles), a coupling agent, etc. The thickness of the non-adhesive layer may be 1 μm or more and 10 μm or less.

[0045] The temporary protective film can be produced, for example, by a method including the steps of applying a varnish containing an acrylic polymer and a crosslinking agent onto a support film and removing the solvent from the coating to form an adhesive layer.

[0046] Next, a method for manufacturing a semiconductor device using the above-mentioned temporary protective film will be described. The method for manufacturing a semiconductor device according to one embodiment includes, in this order, a step S1 of attaching a temporary protective film to one 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 encapsulating the semiconductor element, and a step S4 of peeling the temporary protective film from the substrate. Hereinafter, as an example, a method for manufacturing a semiconductor device (semiconductor device package) in which the substrate is a lead frame will be described in more detail.

[0047] 2 is a cross-sectional view illustrating one embodiment (step S1) of a method for manufacturing a semiconductor device. In step S1, as shown in FIG. 2, a temporary protective film 10 is attached to the back surface, which is one surface of a lead frame 11 having a die pad 11a and inner leads 11b. The temporary protective film 10 is attached in a direction such that the adhesive layer of the temporary protective film 10 contacts the lead frame 11.

[0048] The lead frame 11 may be made of, for example, an iron-based alloy such as alloy 42, copper, or a copper-based alloy. The lead frame 11 may have a molded body made of copper or a copper-based alloy and a coating layer of palladium, gold, silver, or the like that coats the surface of the molded body.

[0049] The temporary protective film 10 has excellent adhesive strength at room temperature (e.g., 25°C), and can be attached to the lead frame 11 at room temperature. The temporary protective film 10 may be attached to the lead frame 11 while being heated and pressed. In this case, the heating temperature may be 150°C or higher and 400°C or lower. The pressure may be 0.5 MPa or higher and 30 MPa or lower. The heating and pressing time may be 1 second or longer and 60 seconds or shorter.

[0050] 3 is a cross-sectional view illustrating one embodiment of a method for manufacturing a semiconductor device (steps S2 and S3). In step S2, as shown in FIG. 3, a semiconductor element 14 is mounted on the surface of the die pad 11a opposite the temporary protective film 10. The semiconductor element 14 is bonded to the die pad 11a via an adhesive (e.g., silver paste). After bonding the semiconductor element 14 to the die pad 11a, reflow connection (CuClip connection, etc.) may be performed at a maximum temperature of 250 to 440°C or 250 to 400°C for 1 to 30 minutes.

[0051] Next, the semiconductor element 14 is connected to the inner leads 11b using wires 12. The wires 12 may be, for example, gold wires, copper wires, or palladium-coated copper wires. The wires 12 may be bonded to the semiconductor element 14 and the inner leads 11b using ultrasonic waves and pressure while being heated at, for example, 200 to 350°C.

[0052] 3, an encapsulating layer 13 is formed to encapsulate the semiconductor element 14 and the wires 12. This results in a temporarily protected encapsulated molded body 20 having the lead frame 11, the semiconductor element 14, and the encapsulating layer 13.

[0053] The sealing layer 13 is formed by sealing molding using a sealing material. By the sealing molding, it is possible to obtain an encapsulated molded body 20 having a plurality of semiconductor elements 14 and the sealing layer 13 that encapsulates them collectively. During the sealing molding, the temporary protective film 10 is provided, thereby preventing the sealing material from creeping around to the back side of the lead frame 11.

[0054] The temperature during the formation of the sealing layer 13 (temperature of the sealing material) may be 140 to 200° C., or 160 to 180° C. The pressure during the formation of the sealing layer may be 6 to 15 MPa, or 7 to 10 MPa. The time for sealing molding may be 1 to 5 minutes, or 2 to 3 minutes.

[0055] The encapsulant may contain, for example, an epoxy resin such as cresol novolac epoxy resin, phenol novolac epoxy resin, biphenyl diepoxy resin, naphthol novolac epoxy resin, etc. The encapsulant may also contain a filler, a flame retardant substance such as a bromine compound, a wax component, etc.

[0056] After the formation of the sealing layer 13 (sealing molding), the temporary protective film 10 is peeled off from the lead frame 11 and the sealing layer 13 of the obtained sealed molded body 20. When the sealing layer 13 is cured, the temporary protective film 10 may be peeled off either before or after the sealing layer 13 is cured.

[0057] The temperature at which the temporary protective film 10 is peeled off is not particularly limited, but may be room temperature (e.g., 5 to 35°C) or higher than the glass transition temperature (Tg) of the adhesive layer. In this case, the temporary protective film 10 is more easily peeled off from the lead frame 11 and the encapsulant. If the Tg of the acrylic polymer in the adhesive layer is, for example, 5°C or lower or 0°C or lower, the Tg of the adhesive layer becomes equal to or lower than room temperature, and the temporary protective film is more easily peeled off at room temperature.

[0058] When the lead frame 11 includes a plurality of patterns having die pads 11 a and inner leads 11 b, the encapsulated body 20 can be divided as necessary to obtain a plurality of semiconductor devices (semiconductor packages) 100 shown in Fig. 4, each having one semiconductor element. That is, when the lead frame 11 has a plurality of die pads 11 a and a semiconductor element 14 is mounted on each of the plurality of die pads 11 a, the manufacturing method according to one embodiment may further include a step of peeling the temporary protective film 10 from the encapsulated body 20 and then dividing the encapsulated body 20 to obtain semiconductor devices (semiconductor packages) 100 having one die pad 11 a and one semiconductor element 14.

[0059] The temporary protective film may be long and may be used in the form of a reel wound around a core. In this case, the temporary protective film is attached to the adherend while being unwound from the reel.

[0060] Fig. 5 is a perspective view showing one embodiment of a reel body. As shown in Fig. 5, a reel body 30 according to one embodiment includes a winding core 31, a temporary protective film 10 wound around the winding core 31, and side plates 32. The widths of the winding core 31 and the temporary protective film 10 (the length in the direction perpendicular to the winding direction) may be 1 mm or more, 5 mm or more, or 10 mm or more, and may be 1000 mm or less, 800 mm or less, or 500 mm or less. In another embodiment, the reel body may not include side plates.

[0061] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to these examples.

[0062] Example 1 Acrylic polymer A-1 having a weight average molecular weight (Mw) of 600,000 and a molecular weight distribution (Mw / Mn) of 1.7 was dissolved in cyclohexanone to obtain a varnish for forming an adhesive layer. The acrylic polymer A-1 was a copolymer of butyl acrylate, acryloylmorpholine, acrylic acid, and other monomers (monomers having hydroxyl groups) in a mass ratio of 80 / 16 / 3 / 1. A polyimide film (thickness: 25 μm, manufactured by DuPont-Toray Co., Ltd., product name: Kapton 100EN) was prepared as a support film. The obtained varnish was applied to one side of the support film. The coating on the support film was dried by heating at 90°C for 1.5 minutes and then at 260°C for 1.5 minutes to form a 2 μm thick adhesive layer. A temporary protective film was thus obtained.

[0063] Examples 2 and 3 Temporary protective films were obtained in the same manner as in Example 1, except that the thickness of the adhesive layer was changed as shown in Table 1.

[0064] Example 4: A compound represented by the following formula (B-1): A temporary protective film was obtained in the same manner as in Example 1, except that a varnish was prepared by adding 10 parts by mass of a crosslinking agent B-1 represented by the formula: and the thickness of the adhesive layer was changed as shown in Table 1.

[0065] Example 5 Instead of 10 parts by mass of the crosslinking agent B-1, a compound of the following formula (B-2): A temporary protective film was obtained in the same manner as in Example 4, except that 7 parts by mass of crosslinking agent B-2 represented by the following formula was added.

[0066] Example 6 A temporary protective film was obtained in the same manner as in Example 1, except that 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 instead of acrylic polymer A-1. The acrylic polymer A-2 was a copolymer of butyl acrylate / acryloylmorpholine / acrylic acid / other monomer (monomer having a hydroxyl group) in a mass ratio of 80 / 16 / 3 / 1.

[0067] Examples 7 and 8 Temporary protective films were obtained in the same manner as in Example 6, except that the thickness of the adhesive layer was changed as shown in Table 1.

[0068] (Comparative Example 1) Instead of 100 parts by mass of acrylic polymer A-1, 100 parts by mass of 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 was used. A varnish was prepared using 30 parts by mass of a crosslinking agent B-3 represented by the formula (I) and the thickness of the adhesive layer was changed as shown in Table 1. A temporary protective film was obtained in the same manner as in Example 1.

[0069] (Comparative Example 2) Instead of 100 parts by mass of acrylic polymer A-1, a varnish was prepared using 30 parts by mass of acrylic polymer a-1, 70 parts by mass of acrylic polymer a-2 (product 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 crosslinking agent B-3. A temporary protective 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.

[0070] (Evaluation of Residue) Each temporary protective film was attached to a CDA194 palladium-plated Cu plate (lead frame, manufactured by Shinko Electric Industries Co., Ltd.) with the adhesive layer facing the lead frame at 25°C and a load of 20 N. The resulting bonded body was heated in an oven under air at 180°C for 60 minutes, then at 200°C for 60 minutes, while changing the heating conditions. The surface of the lead frame opposite the temporary protective film was plasma-treated under an argon gas atmosphere (flow rate: 20 sccm), 150 W, and 15 seconds.

[0071] Using a molding machine (manufactured by Apic Yamada Co., Ltd.), a sealing layer was formed on the surface of the lead frame opposite the temporary protective film using a sealing material (product name: GE-300, manufactured by Showa Denko Materials Co., Ltd.). The sealing conditions were 175°C, 6.8 MPa, and 2 minutes. Thereafter, each temporary protective film was peeled off at a speed of 50 mm / min in a direction 180° relative to the surface of the lead frame at 25°C. The state of the adhesive layer remaining on each of the lead frame and the sealing layer after the temporary protective film was peeled off was confirmed. The proportion of the area occupied by the residue of the adhesive layer relative to the surface area of ​​the lead frame and the surface area of ​​the sealing layer was determined. Based on the proportion of the area occupied by the residue, evaluation was performed according to the following criteria. The results are shown in Table 1. A: Less than 5% B: 5% or more but less than 15% C: 15% or more

[0072]

[0073] 1...support film, 2...adhesive layer, 10...temporary protective film, 11...lead frame, 11a...die pad, 11b...inner lead, 12...wire, 13...encapsulating layer, 14...semiconductor element, 20...encapsulated molded body, 100...semiconductor device.

Claims

1. A temporary protective film for use in the manufacture of semiconductor device, comprising: a support film; and an adhesive layer provided on the support film, wherein the adhesive layer contains 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 alkyl (meth)acrylate and (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 manufacturing a semiconductor device comprising the steps of: attaching a temporary protective film to one side of a substrate; mounting a semiconductor element on the side of the substrate opposite the temporary protective film; encapsulating the semiconductor element; and peeling the temporary protective film from the substrate, in this order; wherein the temporary protective film comprises a support film and an adhesive layer provided on the support film, and the adhesive layer contains 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 method according to claim 4, wherein the acrylic polymer contains alkyl (meth)acrylate and (meth)acryloylmorpholine as monomer units.

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

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