JP2005142208A - Adhesive sheet for manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive sheet for manufacturing semiconductor device that can be removed easily from a semiconductor device without giving any damage to the device after a resin sealing step ends. <P>SOLUTION: The adhesive tape formed by laminating a bonding agent layer 2 upon a substrate film 1 and used for a method of manufacturing semiconductor device is provided with mold release agent layers 3 which can be peeled easily from a sealing resin in the portions of its adhesive surface where no conductive section is formed. The method includes at least a conductive section forming step of partially forming a plurality of conductive sections on the adhesive surface of the adhesive sheet; a semiconductor element mounting step of fixing a plurality of semiconductor elements having electrodes on the adhesive surface of the adhesive sheet and electrically connecting the conductive sections to the electrodes of the semiconductor elements through wires; and a resin sealing step of forming a semiconductor device on the adhesive sheet by sealing the semiconductor elements, wires, and conductive sections with the sealing resin. The method also includes an adhesive sheet removing step of separating the adhesive sheet from the semiconductor device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention belongs to the technical field of semiconductor devices, and particularly relates to an adhesive sheet for manufacturing a semiconductor device used in a process of manufacturing a surface-mount type semiconductor device.

  In recent years, CSP (Chip Size Package, Chip Scale Package) technology has attracted attention as LSI mounting technology. Among these CSP technologies, a package in which lead terminals are taken into the package, represented by QFN (Quad Flatpack Non-leaded Package), is a package type that is particularly noted in terms of miniaturization and high integration. One. Among such QFN manufacturing methods, a plurality of QFN chips are neatly arranged on a die pad in a package pattern region of a lead frame, collectively sealed with a sealing resin in a mold cavity, and then cut. A manufacturing method that dramatically improves the productivity per lead frame area by cutting into individual QFN structures has attracted particular attention.

  In such a QFN manufacturing method that collectively seals a plurality of semiconductor elements, the region clamped by the mold at the time of resin sealing is only outside the resin sealing region wider than the package pattern region. is there. Therefore, in the package pattern region, particularly in the central portion thereof, the outer lead surface cannot be pressed against the mold with sufficient pressure, so it is very difficult to suppress the sealing resin from leaking to the outer lead side. , QFN terminals are likely to be covered with resin.

For this reason, in the QFN manufacturing method as described above, an adhesive tape (adhesive sheet) is attached to the outer side of the lead frame, and the sealing effect by masking this adhesive tape prevents resin leakage to the outer side during resin sealing. A manufacturing method for preventing this is disclosed in Patent Document 1. Further, Patent Document 2 discloses a method for manufacturing a semiconductor device having a so-called leadless structure in which a further reduction in thickness is possible, that is, a conductive part is formed by etching a copper foil on a base material. Proposed. In the method described in Patent Document 2, since the conductive portion is formed on the base material that is an adhesive sheet, it is possible to reduce the thickness of the conductive portion, and to separate the semiconductor device molded with the sealing resin. Since it is not necessary to cut the lead frame at the time of cutting, there is little wear of the blade during dicing.
JP 2000-294580 A Japanese Patent Laid-Open No. 9-252014

  The adhesive sheet used in the method described in Patent Document 1 is bonded to the outer pad surface of the lead frame at the initial stage, and then encapsulated with a sealing resin through a semiconductor element mounting process and a wire bonding process. It is bonded to the stopping process. In addition, the adhesive sheet used in the method described in Patent Document 2 is a method in which a metal foil is first attached, the metal foil is etched into a predetermined pattern, and then a semiconductor element mounting process and a wire bonding process are performed. It is pasted up to the sealing process with a stop resin. Therefore, the adhesive sheet used in these methods not only prevents leakage of the sealing resin, but also has high heat resistance that can withstand the mounting process of semiconductor elements, and delicate operations in the wire bonding process. The characteristics satisfying all these processes are required, such as not hindering the performance, and being able to be peeled off satisfactorily without causing adhesive residue after completion of the sealing process.

  And the adhesive sheet used by such a manufacturing process needs to peel by peeling after completion | finish of a sealing process. In other words, the removal of the adhesive sheet after completion of the sealing process requires a separate peeling process even if it is performed manually or mechanically automatically, and this causes a decrease in productivity or damage to the device during peeling. There was concern.

  This invention is made | formed in view of such a situation, The place made into the objective is that it can perform the adhesive sheet removal process after completion | finish of a resin sealing process simply and without giving a damage with respect to a device. Another object of the present invention is to provide an adhesive sheet for manufacturing a semiconductor device.

  In order to achieve the above object, an adhesive sheet for manufacturing a semiconductor device of the present invention is a conductive part forming step in which a plurality of conductive parts are partially formed on an adhesive surface in an adhesive sheet in which an adhesive layer is laminated on a base film. A semiconductor element mounting step of fixing a plurality of semiconductor elements on which electrodes are formed on an adhesive surface of an adhesive sheet, and electrically connecting a plurality of conductive portions and electrodes of each semiconductor element by wires; and a semiconductor A semiconductor device that performs at least a resin sealing step of sealing an element, a wire, and a conductive portion with a sealing resin to form a semiconductor device on an adhesive sheet, and an adhesive sheet removing step of separating the adhesive sheet from the semiconductor device An adhesive sheet used in the manufacturing method is characterized in that a sealing resin and an easily peelable release agent layer are provided in a portion where a conductive portion on the adhesive surface is not formed.

  Since the adhesive sheet for manufacturing a semiconductor device of the present invention can be easily peeled off from the sealing resin in the adhesive sheet removing step after the resin sealing step by using this in the manufacturing process of the semiconductor device, A stable manufacturing process with little damage to the device can be realized.

  FIG. 1 is a cross-sectional view showing an example of an adhesive sheet for manufacturing a semiconductor device according to the present invention. In this adhesive sheet S, an adhesive layer 2 is laminated on a heat-resistant substrate film 1, and a sealing resin and an easily peelable release agent layer 3 are provided on the adhesive sheet 2 in a pattern. That is, the release agent layer 3 is formed by pattern-applying the release agent on a portion where the conductive portion on the adhesive surface of the adhesive sheet F is not formed.

  As the base film 1 of the adhesive sheet S, plastic base materials such as polyester, polyamide, polyphenylene sulfide, polyetherimide, polyimide and the like, porous base materials, paper base materials such as glassine paper, fine paper, Japanese paper, cellulose, Nonwoven fabric base materials such as polyamide, polyester, and aramid, and metal film base materials such as aluminum foil, SUS foil, and Ni foil are used. The thickness of a base film is 10-200 micrometers normally, Preferably it is 25-100 micrometers. When a film having a thickness of less than 10 μm is used as the substrate film, the handling property is lowered, and when it is thicker than 200 μm, the cost is increased.

  Examples of the mold release agent for forming the mold release agent layer 3 include purified carnauba wax, oxidized polyethylene wax, montanic acid compound, alkyl phosphate ester and the like. The coating amount is not particularly limited, but it is usually formed to a thickness of about 0.01 to 0.5 μm, preferably 0.05 to 0.3 μm. Also, the forming method is not particularly limited, but a gravure coater, screen printing or the like is usually employed to form a pattern.

  As the adhesive composition for forming the adhesive layer 2, various pressure sensitive adhesives such as silicone and acrylic, and various adhesives such as epoxy / rubber and polyimide can be used. Of these, epoxy / rubber thermosetting adhesives are preferred from the viewpoints of heat resistance and adhesiveness.

  Examples of the rubber component used here include those conventionally used for epoxy-based adhesives such as NBR (acrylonitrile butadiene rubber) and acrylic rubber, and commercially available products include “Nipol 1072” (manufactured by Nippon Zeon), “ NipolAR51 "(manufactured by ZEON Corporation). This rubber component is added to give flexibility to the adhesive, but the heat resistance decreases as the content increases. From this viewpoint, the proportion of the rubber component in the organic matter in the adhesive layer is preferably 5 to 40% by weight, and more preferably 10 to 30% by weight. When the amount is less than 5% by weight, the flexibility of the adhesive layer is lowered and the processability is deteriorated. When the amount is more than 40% by weight, the heat resistance is lowered and adhesive residue is likely to occur.

  The epoxy resin that is a curing component is a compound containing two or more epoxy groups in the molecule, such as glycidylamine acid epoxy resin, bisphenol F type epoxy resin, bisphenol A type epoxy resin, phenol novolac type epoxy resin, cresol. Examples include novolac type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, aliphatic epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, spiro ring-containing epoxy resins, halogenated epoxy resins, etc. Alternatively, a mixture of two or more types is used. The proportion of these used is suitably 60 to 95% by weight, more preferably 70 to 90% by weight, based on 100 parts by weight of the organic matter. If it is less than 60% by weight, curing is insufficient and heat resistance is insufficient, and if it exceeds 95% by weight, flexibility is lowered and workability is deteriorated. The epoxy equivalent of the epoxy resin is 1000 g / eq or less, preferably 500 g / eq or less. When the epoxy equivalent is greater than 1000 g / eq, the crosslink density is reduced, so that the adhesive strength after curing is increased, and adhesive residue is likely to occur during peeling after the resin sealing step.

  Moreover, you may add the hardening | curing agent for hardening the epoxy resin which is a hardening component. As a curing agent for the epoxy resin, phenol resin, various imidazole compounds and derivatives thereof, hydrazide compound, dicyandiamide, and those obtained by encapsulating them can be used. In particular, when a phenol resin is used as a curing agent, a phosphorus compound such as triphenylphosphine can also be used as a curing accelerator. When a phenol resin is selected as the curing agent, a part of the added amount of the epoxy resin can be replaced with the phenol resin so that the amount of the curing agent used is equivalent to that of the epoxy resin. The other curing agent and curing accelerator are used in an amount of 0.5 to 5% by weight, preferably 0.5 to 3% by weight, based on 100 parts by weight of the organic matter.

  The adhesive composition for forming the adhesive layer 2 includes an inorganic filler, an organic filler, a pigment, an anti-aging agent, a silane coupling agent, and a tackifier within a range that does not deteriorate various properties of the adhesive film. Various known additives such as can be added as necessary. In particular, the addition of an anti-aging agent is effective in preventing deterioration at high temperatures.

  An adhesive sheet can be manufactured by a general method using the adhesive composition adjusted in this way. For example, a method of dissolving in a solvent and applying to a base film and forming an adhesive sheet by heat drying, a method of applying the composition to a base film as an aqueous dispersion solution, and forming an adhesive sheet by heat drying Can be mentioned. Here, the solvent is not particularly limited, but a ketone solvent such as methyl ethyl ketone has good solubility and is preferably used.

  The adhesive sheet is prepared by providing an adhesive layer having a thickness of usually 1 to 50 μm as a layer on a base film, and is used in the form of a sheet or a tape. Then, a release agent is applied in a pattern to a portion of the adhesive sheet where the conductive portion is not formed, whereby the adhesive sheet S for manufacturing a semiconductor device of the present invention is obtained.

  FIG. 2 is a process diagram showing a procedure for manufacturing a semiconductor device using the adhesive sheet for manufacturing a semiconductor device of the present invention. The process diagram will be described as follows.

  First, as shown in FIG. 2A, a plurality of conductive portions 4 are partially formed on the adhesive layer 2 in the adhesive sheet S. The number of conductive portions 4 corresponding to the number of electrodes of a plurality of semiconductor elements to be mounted is formed in a pattern. As a method of forming the conductive portion 4 on the adhesive surface of the adhesive sheet S, a method of sticking the adhesive sheet S to the outer side of the lead frame, or a method of forming a conductive portion by bonding copper foil to the adhesive sheet S and etching. There is a way to do it.

  Next, as shown in FIG. 2B, the semiconductor element 10 on which the electrode 11 is formed is fixed to a predetermined position via the adhesive layer 2, and the plurality of conductive portions 4 and the electrodes 11 of the semiconductor element 10 are Are electrically connected by a wire 12. In addition, when the chip size is small and the fixing force by the adhesive sheet S is insufficient, the semiconductor element 10 is firmly fixed on the adhesive sheet S with a commercially available die attach material such as a silver paste or a die attach film. It doesn't matter.

  Next, as shown in FIG. 2C, the semiconductor element 10, the wire 12, and the conductive portion 4 are sealed with a sealing resin 13 to form a semiconductor device on the adhesive sheet S. Sealing with the sealing resin 13 is performed using a mold by a normal transfer molding method. After molding, post-curing heating of the sealing resin 13 is performed as necessary. The post-curing heating may be before or after separation of the adhesive tape S described later.

  Subsequently, the adhesive sheet is removed from the semiconductor device. In this case, the adhesive sheet S is peeled off by peeling, but the adhesive sheet S can be easily removed without damaging the semiconductor element 10 because there is an easily peelable release agent layer 3 between the adhesive sheet S and the sealing resin 13. As a result, the semiconductor device shown in FIG. 2D is obtained.

  In the semiconductor device manufactured in this way, the plurality of electrodes 11 on the upper side of the semiconductor element 10 and the upper portions of the plurality of conductive portions 4 are electrically connected by wires 12 respectively, and the semiconductor element 10 and the wires 12 are electrically connected. The portion 4 is sealed with a sealing resin 13 to protect it from the external environment. The lower side of the semiconductor element 10 where the electrode 11 is not formed and the lower side of the conductive portion 4 not connected to the wire 12 are exposed on the back surface of the sealing resin 13. As described above, the semiconductor device obtained by the manufacturing method of the present invention has a structure in which the lower surface of the semiconductor element 10 and the lower surface of the conductive portion 4 are exposed on the surface of the sealing resin 13, and the adhesive for fixing the die pad or the semiconductor element. It is a leadless structure without a layer.

  It is practical to manufacture a plurality of semiconductor devices together. Therefore, a plurality of semiconductor elements are collectively sealed with resin, and after the resin sealing, the adhesive tape is separated, and then cut into a predetermined size by dicer cutting or punching to obtain a semiconductor device. Will get.

  30 parts by weight of acrylonitrile butadiene rubber (Nippon Zeon "Nipol 1072J"), bisphenol A type epoxy resin (Japan Epoxy Resin "Ebi Coat 828", epoxy equivalent: 190 g / eq) 65 parts by weight, imidazole (Shikoku Chemicals "C11Z") 5 parts by weight was blended and dissolved in a methyl ethyl ketone solvent to obtain a solid content concentration of 40% by weight to obtain an adhesive solution. This adhesive solution was applied onto a copper foil having a thickness of 35 μm, and then dried at 150 ° C. for 3 minutes, thereby forming an adhesive layer having a thickness of 20 μm to obtain an adhesive sheet. Then, a refined carnauba wax diluted with a solvent and adjusted to 0.5 wt% is coated on the adhesive surface of the adhesive sheet with a gravure coater, and a pattern release agent A layer was provided to obtain an adhesive sheet for manufacturing a semiconductor device.

  24 parts by weight of acrylonitrile butadiene rubber (“Nipol 1072J” manufactured by Nippon Zeon), 65 parts by weight of bisphenol A type epoxy resin (“Ebicoat 1002” manufactured by Japan Epoxy Resin, epoxy equivalent: 650 g / eq), phenol resin (“P- 180 ") 10 parts by weight and 1 part by weight of triphenylphosphine (" TPP "manufactured by Hokuko Kasei) were blended and dissolved in a methyl ethyl ketone solvent to obtain a solid concentration of 40% by weight to obtain an adhesive solution. This adhesive solution was applied onto a copper foil having a thickness of 35 μm, and then dried at 150 ° C. for 3 minutes, thereby forming an adhesive layer having a thickness of 20 μm to obtain an adhesive sheet. Next, an oxide polyethylene wax is dispersed in a solvent and adjusted to 0.5 wt%, and this is coated on the adhesive surface of the adhesive sheet with a gravure coater to form a pattern release agent A layer was provided to obtain an adhesive sheet for manufacturing a semiconductor device.

  As a comparative example, an adhesive sheet having no release agent layer in Example 1 was produced. And about the adhesive sheet of Example 1, 2 and the adhesive sheet of a comparative example, peelability and adhesive residue property were evaluated with the following method. These results were as shown in Table 1.

[Peelability]
Each adhesive sheet was cured under conditions of 150 ° C. × 1 hr. Next, using a molding machine (“Model-T-series” manufactured by TOWA), these were molded with an epoxy-based sealing resin (“HC-300” manufactured by Nitto Denko). The molding conditions are 175 ° C., preheating 40 seconds, injection time 11.5 seconds, and curing time 120 seconds. Then, the peelability of sealing resin and an adhesive sheet was confirmed by peeling an adhesive sheet.

[Adhesive residue]
Lamination conditions for each adhesive sheet on the outer pad side of a copper lead frame (Cu-L / F) in which 4 × 4 16-pin QFNs are arranged on each side are laminated at 100 ° C. × 0.5 MPa × 50 mm / min. Attach together. Next, the adhesive sheet of the example was cured under conditions of 150 ° C. × 1 hr. Furthermore, using a molding machine (“Model-T-series” manufactured by TOWA), molding was performed with an epoxy-based sealing resin (“HC-300” manufactured by Nitto Denko). The molding conditions were 175 ° C., preheating for 40 seconds, The injection time was 11.5 seconds and the curing time was 120 seconds.Then, the adhesive sheet was peeled off, and the presence or absence of adhesive residue on the sealing resin surface was confirmed.

  As is apparent from Table 1, when the adhesive sheets of Examples 1 and 2 were used, the peelability with respect to the sealing resin was excellent, and no adhesive residue was observed. On the other hand, when the adhesive sheet of the comparative example is used, no adhesive residue is seen, but stress is generated on the sealing resin at the time of peeling, and the device is broken for 5 out of 64 pieces. It was.

It is sectional drawing which shows an example of the adhesive sheet for semiconductor device manufacture which concerns on this invention. It is process drawing which shows the procedure which manufactures a semiconductor device using the adhesive sheet for semiconductor device manufacture of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS S Adhesive sheet 1 Base film 2 Adhesive layer 3 Release agent layer 4 Conductive part 10 Semiconductor element 11 Electrode 12 Wire 13 Sealing resin

Claims (3)

  A conductive part forming step for forming a plurality of conductive parts partially on an adhesive surface in an adhesive sheet in which an adhesive layer is laminated on a base film, and a plurality of semiconductor elements on which electrodes are formed are bonded to the adhesive sheet. A semiconductor element mounting process for fixing the conductive elements and the electrodes of each semiconductor element by wires, and sealing the semiconductor elements, wires and conductive parts with a sealing resin. An adhesive sheet used in a method for manufacturing a semiconductor device that performs at least a resin sealing step for forming a semiconductor device and an adhesive sheet removing step for separating the adhesive sheet from the semiconductor device, and forming a conductive portion on the adhesive surface An adhesive sheet for manufacturing a semiconductor device, characterized in that a sealing resin and an easily peelable release agent layer are provided in a portion not to be used.   2. The semiconductor device manufacturing method according to claim 1, wherein any one of refined carnauba wax, oxidized polyethylene wax, a montanic acid compound, and an alkyl phosphate ester is used as a release agent for forming the release agent layer. Adhesive sheet. 2. An adhesive sheet using a thermosetting adhesive comprising a rubber component, an epoxy resin as a curing component, and a curing agent thereof is used for the adhesive composition forming the adhesive layer. The adhesive sheet for semiconductor device manufacture as described in 2.

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