JP2005123319A - Manufacturing method of semiconductor device and release sheet used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for sufficiently cleaning an inner surface of a metallic mold while a mold release sheet is continuously supplied in the method for resin-sealing a substrate on which a semiconductor chip is loaded by using the release sheet and manufacturing a semiconductor device. <P>SOLUTION: The manufacturing method of a semiconductor device includes at least a process for providing the mold release sheet (1) between a sealed face on which a connection circuit (22) is arranged in the substrate (21) on which the semiconductor chip (2) is loaded and the inner face of the metallic mold (4) and for sealing resin (5) so that the connection circuit (22) is exposed. The release sheet (1) is continuously conveyed along the inner face of the metallic mold (4) whenever the resin sealing process is performed. A surface on a side arranged on the inner face of the metallic mold (4) of the mold resin sheet (1) has a function for cleaning the inner face of the metallic mold. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a semiconductor device and a release sheet used in the manufacturing method. The method of manufacturing a semiconductor device according to the present invention includes a CSP (Chip Scale / Size Package) technology in LSI mounting technology, particularly, among those technologies, QFN (Quad Flat Non-leaded package), SON (Small Outline Non-leaded package). It is useful for forming a package in which a connection circuit such as a lead terminal is incorporated in the package.

  Conventionally, a semiconductor device is manufactured by sealing a substrate on which a semiconductor chip is mounted with a sealing resin to form a package. Since the sealing step is performed in the mold, a method of applying a release sheet to the mold inner surface is widely used in order to improve the mold release property between the mold inner surface and the sealing resin.

  In recent LSI mounting technology, a single-side sealed package represented by QFN or the like is known as one of the package types that are particularly noted in terms of miniaturization. When producing such a single-side sealed package, it is effective to use a release sheet as a packing material so that the resin does not go around the surface to be sealed and the opposite side. As the release sheet, for example, a sheet having an improved sealing effect with respect to the substrate is known by giving the surface of the substrate disposed on the surface to be sealed an adhesive property (Patent Document 1). reference). Thus, using a release sheet between the inner surface of the mold and the surface to be sealed of the substrate is known as an effective method in the manufacture of semiconductor devices in recent years.

  In particular, in recent years, a reel function is arranged before and after the casting mold, and a method of continuously supplying a roll-shaped release sheet after the sealing process is performed is a reel-to-reel method. to Real) method, etc., and is known as a technique advantageous to an automation mold apparatus for continuous production (see Patent Document 2).

  On the other hand, in the manufacture of such a semiconductor device, a metal mold used for resin sealing is required to have high accuracy in order to prevent the occurrence of resin leakage. That is, if foreign matter or contaminants adhere to the inner surface of the mold, the same state as that in which the accuracy is impaired may be caused, which may cause resin leakage or poor resin fluidity. Therefore, in continuous production, it is necessary to frequently clean the inner surface of the mold every time resin sealing is performed in order to keep a clean state. Cleaning of foreign matters and contaminants such as casting resin scattered on the inner surface of the mold was performed using an air brush or the like.

However, in the method of continuously supplying the release sheet into the mold, it is necessary to remove the release sheet once and to check the cleanliness of the inner surface of the mold after the resin sealing step. Therefore, it has been difficult to satisfactorily perform the workability related to the continuous supply of the release sheet without impairing the maintainability related to the cleaning of the inner surface of the mold.
JP 2000-294580 A US Pat. No. 6,033,933

  The present invention relates to a method of manufacturing a semiconductor device by resin-sealing a substrate on which a semiconductor chip is mounted using a release sheet, and provides good cleaning of the inner surface of the mold while continuously supplying the release sheet It is an object of the present invention to provide a method for manufacturing a semiconductor device that can be performed in a simple manner.

  Another object of the present invention is to provide a release sheet for manufacturing a semiconductor device used in the method for manufacturing a semiconductor device.

  As a result of intensive studies to achieve the above object, the present inventors have found a semiconductor device manufacturing method and a release sheet used therefor, and have completed the present invention.

That is, the present invention is a method for manufacturing a semiconductor device including at least a step of resin sealing with a release sheet interposed between a sealed surface of a substrate on which a semiconductor chip is mounted and at least one mold inner surface. And
The release sheet is continuously conveyed along the inner surface of the mold every time after the resin sealing step is performed,
And the surface of the side arrange | positioned at the metal mold | die inner surface of the said release sheet has a function which cleans a metal mold | die inner surface, It is related with the manufacturing method of the semiconductor device characterized by the above-mentioned.

  In the manufacturing method of the semiconductor device, a release sheet having a surface showing a function of cleaning the inner surface of the mold on one side is used and disposed on the inner surface of the mold. Therefore, after the resin sealing step, the release sheet is transported along the inner surface of the mold and supplied to remove foreign matters and contaminants generated in the resin sealing step by the purification function surface of the release sheet. be able to. Therefore, according to the manufacturing method of the semiconductor device, it is possible to have maintenance work related to cleaning of the inner surface of the mold while satisfying workability related to continuous supply of the release sheet.

Moreover, this invention is a release sheet used for the manufacturing method of the said semiconductor device,
The surface on the side to be arranged on the surface to be sealed of the substrate has a release function,
The surface of the side arrange | positioned at the said metal mold | die inner surface has a function which cleans a metal mold | die inner surface, It is related with the release sheet for semiconductor device manufacture characterized by the above-mentioned.

  As the release sheet for manufacturing a semiconductor device, a sheet in which the surface on the inner surface of the mold is a nonwoven fabric can be suitably used.

  Further, as the release sheet for manufacturing a semiconductor device, a sheet whose surface on the inner surface of the mold is paper can be suitably used.

  In addition, as the release sheet for manufacturing a semiconductor device, a sheet in which the surface on the inner surface of the mold is formed by an adhesive layer can be suitably used.

  These release sheets for manufacturing semiconductor devices have a particularly excellent cleaning effect against foreign matters generated in the resin sealing process.

  Hereinafter, a release sheet for manufacturing a semiconductor device and a method for manufacturing the semiconductor device will be described in order with reference to the drawings.

(Release sheet for semiconductor device manufacturing)
As shown in FIG. 1, the release sheet (1) for manufacturing a semiconductor device of the present invention has a layer (11) having a release function on one side and a function of cleaning the inner surface of the mold on the other side. Those having at least the layer (12) having In the method for manufacturing a semiconductor device, the release sheet (1) is disposed such that the release layer (11) is on the sealed surface side of the substrate and the clean layer (12) is on the inner surface side of the mold. .

  Examples of the material for forming the release layer (11) include materials generally used for release sheets. The material is not particularly limited. For example, polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether Examples thereof include fluororesins such as a copolymer (PFA), polyvinylidene fluoride (PVdF), and fluororubber.

  Examples of the material for forming the release layer (11) include polyimide (PI), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN). In addition, these polyimides can be used with a heat-resistant and releasable pressure-sensitive adhesive layer, and can effectively obtain adhesion to the substrate, etc., thus preventing flashing of the resin. It has a high masking effect and is widely used as a material for a release sheet together with a fluororesin.

  The thickness of the release layer (11) is usually preferably about 1 to 1000 μm, more preferably 5 to 200 μm, since an effect as a packing material that suppresses resin leakage during resin sealing is required.

  The cleaning layer (12) roughly shows at least one of the effects related to the cleaning function 1) to 3) shown below. That is, 1) the effect of polishing the inner surface of the mold by rubbing when the release sheet is moved along the mold, and 2) adhering foreign matter adhering to the mold surface when in close contact with the mold. Mainly, the effect of removing foreign matter from the inner surface of the mold, 3) the effect of removing contaminants from the inner surface of the mold by absorbing the contaminants adhering to the inner surface of the mold when closely attached to the inner surface of the mold It is given to. The cleaning layer (12) has these cleaning functions alone or in combination, so that the surface in the mold can be cleaned. As the clean layer (12), a layer having heat resistance for the resin sealing step is used. Specifically, a polymer material that does not cause a heat change such as gas generation accompanied by significant heat shrinkage or deterioration in a temperature range of about 170 to 180 ° C. is preferably used.

  Examples of the material for forming the clean layer (12) include nonwoven fabric, paper, and a layer having adhesiveness. In particular, when a nonwoven fabric or paper is used as a raw material, it has both the effect of 1) rubbing the inner surface of the mold and the effect of 3) impregnating and absorbing contaminants on the inner surface of the mold. As the nonwoven fabric, in addition to those made of nylon or polyester materials, those made of aramid fibers having excellent heat resistance are preferably used. The paper is not particularly limited, and common western paper can be used. Particularly, paper having a large fiber gap and high porosity, such as Japanese paper, is preferably used because it easily entangles contaminants on the inner surface of the mold.

  The adhesive layer is not particularly limited as long as it does not strongly adhere to the inner surface of the mold and can be peeled off after the resin sealing step. A material using an adhesive and an acrylic adhesive is preferable. These pressure-sensitive adhesives also have a good effect of 2) for removing foreign substances by adhesion.

  In addition, the cleaning layer (12) is supplementarily impregnated with a chemical cleaning agent such as a surfactant or an abrasive in advance, and this is adhered to the surface in the mold, thereby cleaning them. It is also possible to improve the function of cleaning the surface. When a nonwoven fabric or paper is used as a material for forming the cleaning layer (12), impregnation with an auxiliary chemical cleaning agent can be easily performed.

  The thickness of the cleaning layer (12) is preferably about 1 to 1000 μm, preferably 5 to 200 μm because it preferably follows the steps and protrusions of the mold to some extent.

(Semiconductor device manufacturing method: resin sealing method)
The method for manufacturing a semiconductor device of the present invention includes at least a step of resin sealing with a release sheet interposed between a surface to be sealed of a substrate on which a semiconductor chip is mounted and at least one mold inner surface. That is, the release sheet is interposed on at least one side of the upper mold inner surface or the lower mold inner surface.

  FIG. 2 shows a resin-sealed structure in which a release sheet is interposed between a surface to be sealed in which a connection circuit is disposed on a substrate on which a semiconductor chip is mounted and an inner surface of a mold so that the connection circuit is exposed. This is the case. FIGS. 2A to 2C show an example of a method for manufacturing a semiconductor device using the release sheet (1) of the present invention.

  According to the manufacturing method, a semiconductor device in which the semiconductor chip (2) is mounted and packaged can be obtained. Examples of the semiconductor chip (2) include a silicon chip to which various circuit patterns are applied.

  This semiconductor chip (2) is generally mounted on a substrate (21). The substrate (21) has a connection circuit (22) connected to the semiconductor chip (2). Generally, a glass epoxy organic substrate, an inorganic substrate such as ceramic, a copper lead frame, or the like is used. can give. Examples of the connection circuit (22) include a terminal or an electrode. The substrate (2) is not particularly limited as long as it is a semiconductor device that is finally packaged.

  The mounting of the semiconductor chip (2) means that the semiconductor chip (2) is fixed for connection with the substrate (21). For example, when there is a die for mounting the semiconductor chip (2) on the substrate (21) itself, the semiconductor chip (2) is fixed to them with an adhesive or fixed with a double-sided tape or the like. Further, when the substrate (21) is a substrate that does not directly have a die, for example, a fixing portion may be temporarily provided with a tape or the like, and the tape or the like may be peeled off after being finally sealed with a sealing resin. However, these are also temporarily fixed on a tape surface or the like for connection with the semiconductor chip (2), and finally packaged. FIG. 2 shows the case where the substrate (21) does not have a die.

  The substrate (21) on which these semiconductor chips (2) are mounted is generally molded by a sealing resin (5) in a mold (3, 4) through a connection process such as wire bonding to form a semiconductor package. . In FIG. 2, the connection circuit (22) is connected by wire bonding (23).

  In FIG. 2, the case where QFN is manufactured by resin sealing is illustrated. The semiconductor chip (2) to be sealed is usually divided into a plurality of units (FIG. 4 (b) shows one unit) in the lead frame as shown in FIG. Are respectively wire-bonded or the like. 2A to 2C are illustrated for one unit for easy understanding.

  In FIG. 2 (a), the lead terminal (22) is bonded to the electrode of the semiconductor chip (2) and the lead terminal (22) of the lead frame (21) with a wire (23) such as gold. It arrange | positions so that it may become the metal mold | die (4) side. The release sheet (1) is interposed between the lead frame (21) and the inner surface of the lower mold (4). The release sheet (1) is arranged along the lower mold (4) so as to be continuously supplied from the unwinding reel (6) to the take-up reel (7). The release sheet (1) is disposed such that the side disposed on the inner surface of the lower mold (4) is the clean layer (12).

  On the other hand, the semiconductor chip (2) is disposed in the cavity (31) of the upper mold (3). The arrangement of the lead terminals (22) is not limited to the case where the lead terminals (22) are arranged at intervals around the entire circumference as shown in FIG. 4 (b), but may be arranged on the entire surface or only on the opposite side.

  Next, as shown in FIG. 2B, after the upper mold (3) and the lower upper mold (4) are closed, the sealing resin (5) is injected into the cavity (31) by transfer molding.・ Curing. For such transfer molding, a thermosetting resin such as an epoxy resin is usually used. The sealing step is performed such that the lead terminal (22) is exposed with the release sheet (1) interposed therebetween.

  Thereafter, the mold is opened as shown in FIG. Thereafter, the release sheet (1) is conveyed along the inner surface of the lower mold (4), so that the clean layer (12) of the release sheet (1) cleans the inner surface of the lower mold (4). Turn into. Every time after the resin sealing step, the conveying step of the release sheet (1) is continuously performed. After the resin sealing step, after removing the mold and after-curing as necessary, the lead frame (21) is appropriately cut by trimming while leaving the lead terminal (22).

  FIG. 3 shows a case where the release sheet (1) is conveyed along the inner surface of the upper mold (3). In FIG. 3, it installs so that the clean layer (12) of a release sheet (1) may become the inner surface side of an upper metal mold | die (3). In other respects, operations similar to those shown in FIGS. 2A to 2C are performed in FIGS.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

Example 1
A PTFE release sheet (thickness of about 25 μm: release layer) obtained by casting a fluororesin dispersion is laminated by hot pressing with about 100 μm of Japanese paper through an ETFE film, and the clean layer is paper. A release sheet was made as a raw material.

  This release sheet was supplied by the Real to Real method so that the clean layer (paper surface) was rubbed against the inner surface side of the lower mold. On the other hand, on the surface of the release sheet PTFE side, a semiconductor chip is mounted on a copper lead frame in which 4 × 4 16-pin QFNs are arranged on one side, and wire bonding is performed with gold wires did. Next, the upper mold was closed so that the semiconductor chip was placed in the cavity of the upper mold.

  Next, the substrate on which the semiconductor chip was mounted was molded with a sealing resin under the following conditions. Using an epoxy-based sealing resin (manufactured by Nitto Denko Corporation: HC-300B type) and a mold machine (Model-Y-series manufactured by TOWA) at 175 ° C., preheating setting for 3 seconds, injection time of 12 seconds, curing time of 90 After molding in seconds, the mold was opened and the package sealed by the Real to Real method was sent out. This operation of resin sealing and release sheet conveyance was continuously repeated.

  When 100 shots of resin sealing was carried out while exchanging the reels every 25 shots of the above operation, the surface (inner surface) of the lower mold to which the release sheet was supplied was not particularly cleaned but foreign matter, etc. No adhesion was observed, and paper was polished to every corner of the mold and was in good condition. In addition, the semiconductor devices in which the molding was completed did not cause resin leakage and had a casting success rate of 100%.

Example 2
A 25 μm thick polyimide film (Toray DuPont: Kapton 100H) as a base material (release layer) and a silicone adhesive (Toray DuPont, SD4580), about 25 μm thick adhesive layer (cleaning layer) A release sheet provided with was prepared.

  In Example 1, the same operation as in Example 1 was performed, except that the release sheet prepared above was used. When 100 shots of resin sealing was carried out, the surface (inner surface) of the lower mold to which the release sheet was supplied was not particularly cleaned, but no foreign matter was adhered to it. The paper was polished and in good condition. In addition, the semiconductor devices in which the molding was completed did not cause resin leakage and had a casting success rate of 100%.

Comparative Example 1
In Example 1, the same operation as in Example 1 was performed, except that a PTFE release sheet (thickness: about 25 μm) obtained by casting a fluorine dispersion was used as the release sheet. When 100 shots of resin sealing was performed, foreign matter that appeared to be mixed during reel replacement adhered to the surface (inner surface) of the lower mold, and significant unevenness was generated. For this reason, in the semiconductor device after 50 shot replacement, the contact portion caused by the foreign matter causes resin leakage, causing a resin leakage failure, and the casting success rate was 49%.

It is an example of the release sheet for semiconductor device manufacture of this invention. It is an example of the process drawing of the manufacturing method of the semiconductor device of this invention. It is an example of the process drawing of the manufacturing method of the semiconductor device of this invention. It is an example of the lead frame used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Release sheet 11 Release layer 12 Clean layer 2 Semiconductor chip 21 Substrate 3 Upper die 4 Lower die 5 Sealing resin

Claims (5)

A method for manufacturing a semiconductor device comprising at least a step of resin sealing with a release sheet interposed between a sealed surface of a substrate on which a semiconductor chip is mounted and at least one mold inner surface,
The release sheet is continuously conveyed along the inner surface of the mold every time after the resin sealing step is performed,
And the manufacturing method of the semiconductor device characterized by the surface of the side arrange | positioned at the metal mold | die inner surface of the said release sheet having the function to clean a metal mold | die inner surface. It is a release sheet used for the manufacturing method of the semiconductor device of Claim 1, Comprising:
The surface on the side to be arranged on the surface to be sealed of the substrate has a release function,
A mold release sheet for manufacturing a semiconductor device, wherein the surface on the inner surface of the mold has a function of cleaning the inner surface of the mold.   The release sheet for manufacturing a semiconductor device according to claim 2, wherein the surface on the side disposed on the inner surface of the mold is a nonwoven fabric.   3. The release sheet for manufacturing a semiconductor device according to claim 2, wherein the surface on the side disposed on the inner surface of the mold is paper. The release sheet for manufacturing a semiconductor device according to claim 2, wherein the surface on the side disposed on the inner surface of the mold is formed of an adhesive layer.

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