Apparatus and method for manufacturing a semiconductor device

An apparatus for manufacturing a semiconductor device includes an upper mold (21), a lower mold (22), and a plate (30, 130, 230) that includes at least one cavity (31) that receives resin and defines an outer shape and a thickness of a resin sealing portion, and a gate (32) through which the resin is guided to the cavity (31), the plate (30) being interposed between the upper mold (21) and the lower mold (22). The plate (130) further includes a resin film (132) fixed by viscoelastic or adhesive bonding to a side of thin plates (131) towards a substrate on which electrodes are provided. The semiconductor device is provided which has no resin burrs that occur on a substrate in an end portion of the molded body. The plate (30, 130, 230) is formed by multiple thin plates (231, 232, 233) joined by welding or positioned by positioning pins (237, 238).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus and a method for manufacturing semiconductor devices.

2. Description of the Related Art

A conventional transfer molding method injects seal resin between upper and lower molds in which a semiconductor device is placed and a substrate thereof is clamped. A gate for resin injection is provided on a surface of the semiconductor device on which electrodes for interconnections are provided. This arrangement of the gate, however, requires a large substrate size.

FIGS. 1A and 1Brelate to a semiconductor device with two Ball Grid Array (BGA) type packages and illustrate the lower one1of the two packages. The lower package has an interposer2, electrode pads3, a gate4for injecting resin and a resin sealing portion5. The electrode pads3are used to make connections with external electrodes of the upper package.FIGS. 2A and 2Bshow another conventional package11. The package11has an interposer12, electrode pads13, a gate14for resin injection, and a resin sealing portion15. As to the package1, a semiconductor device has an area that is located in a corner and corresponds to the gate4, the area being plated with gold which has a poor adhesiveness to the seal resin. This gold plating is intended to allow easy removal of the gate4after seal resin molding. The area plated with gold does not allow electrode pads3for making electrical connections to be arranged therein and needs a large portion of the substrate for the gold-plated area. This prevents miniaturization of the semiconductor device.

A proposal directed to eliminating the above problems has been proposed in which a gate is provided on an upper surface of the seal resin. This proposal does not use the upper and lower molds but employs three molds, namely, an upper mold, an intermediate mold and a lower mold. The intermediate mold has a cavity for a molded body and a gate for resin injection. However, the structure of the proposed molds makes it difficult to remove the gate and runner resin that remain after molding. Particularly, there is a need to clean the inner wall of the gate each time molding is performed because the injection port is small.

In order to solve the above problem, a plate mold method as shown inFIGS. 3A through 3Fhas been proposed (Japanese Patent Application Publication No. 2004-193582, hereinafter referred to as Document 1). An apparatus20for manufacturing a semiconductor device has an upper mold21, a lower mold22, and a plate25in which a cavity26is formed. A substrate27on which a semiconductor chip (not shown) is mounded is placed in a substrate holding portion defined in an open state of the upper mold21and the lower mold22. Next, the plate25is disposed between the upper mold21and the lower mold22. Melted resin is supplied via a supply port24formed on the lower mold22. The melted resin supplied via the supply port24is injected into the cavity26via a runner23. The state in which the cavity26is filled with the resin is held for a few minutes in order to cure the resin. A sealing portion28is formed into the same shape as that of the cavity26. Thereafter, the lower mold22is moved down to separate the molded body and the upper mold21from each other. Unnecessary resin29is removed and the plate25is taken away, so that the device with the semiconductor chip sealed with resin can be completed.

However, the conventional art disclosed in Document 1 has a disadvantage in that a gate residual210frequently results. When there is the gate residual210, or resin burr, after removal of the unnecessary resin29, the semiconductor device is thickened. Alternatively, if the gate is undercut, the semiconductor device may have an exposed portion.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above circumstances and provides an apparatus and method for manufacturing a semiconductor device having no resin burrs on an upper surface of a molded body.

An apparatus for manufacturing a semiconductor device includes an upper mold, a lower mold, and a plate that includes a cavity for receiving resin and defining an outer shape and a thickness of a resin sealing portion and a gate through which the resin is guided to the cavity to which the gate is connected, the plate being interposed between the upper mold and the lower mold. The present invention employs the cavity for forming the shaped device by injecting resin into the plate and curing the resin and employs the gate for guiding the resin to the cavity and, thus, is capable of providing a semiconductor device without resin burrs on a substrate in an end portion of the molded device. Even if a gate residual exists, it can be prevented from protruding from the upper surface of the molded body. Thus, the device after gate break will have uniform height. Further, the semiconductor device does not have any exposed portion after the gate is undercut.

The cavity may have an opening area that varies in the thickness direction of the plate. The gate may also have an opening area that varies in the thickness direction of the plate and may be provided at a position wherein the resin is supplied from the side of the cavity. The plate may further include a resin film provided on a side thereof that contacts a substrate of the semiconductor device. Thus, the resin film absorbs a roughness due to the presence of interconnection lines on the substrate and prevents resin from being leaked to electrodes provided on the substrate.

The plate may additionally include a resin film, provided on a side thereof, which contacts a substrate of the semiconductor device and is fixed thereto by viscoelastic or adhesive bonding. The plate may also include a resin film provided on a side thereof that contacts a substrate of the semiconductor device, the plate and the resin film having a through hole into which a given pin is inserted.

The plate may include multiple laminated thin plates. The plate may also include multiple thin plates that are laminated and bonded by welding. If the plate is formed by scraping metal, the plate will not have uniform thickness and will likely be warped. The use of a defective plate may cause a mismatch of the outer size with the specification or a joint failure and may decrease the production yield. In contrast, thin plates may be formed by metal rolling wherein their formation is very precisely regulated to provide a given thickness. Thin plates thus formed are laminated to form the plate having a uniform thickness and distributing stress to the thin plates, so that warping of the plate can be restricted and production yield of the semiconductor devices can be improved.

The plate may include multiple thin plates that are laminated with the gate provided in an uppermost one of the multiple thin plates. The plate may also include multiple thin plates that are laminated and may have through holes that are provided in corresponding positions, a pin, such as a positioning pin, being inserted into the through holes. Thus, the plate may be fixed to the upper and lower molds by the positioning pin. In addition, the plate may have cavities and a supply port via which the resin is supplied, and the cavities may be symmetrically positioned so as to interpose the supply port between the cavities. Also, the plate may have a portion that contacts the resin, such portion being coated with fluorocarbon resin or being plated with gold to improve the detachability of the plate. The plate may further include a frame provided along an outer circumference of the plate and having rigidity, so that the plate can be prevented from being deformed even when the plate is thin.

According to another aspect of the present invention, there is provided a method of fabricating a semiconductor device which includes the steps of placing a plate between an upper mold and a lower mold, the plate having a cavity and a substrate of the semiconductor device being provided on the plate and supplying resin to the cavity from a supply port provided in the lower mold via a gate connected to the cavity and provided in the plate. The present invention employs the cavity for forming the shaped device by injecting resin into the plate and curing the resin, and employs the gate for guiding the resin to the cavity, thereby reliably providing a semiconductor device unlikely to have resin burrs on a substrate in an end portion of the molded device. Even if a gate residual exists, it can be prevented from protruding from the upper surface of the molded body. Thus, the device after gate break will have uniform height. Further, the semiconductor device does not have any exposed portion after the gate is undercut.

The cavity may have an opening area that varies in a thickness direction. Additionally, the gate may have an opening area that varies in a thickness direction and may be provided at a position in which the resin is supplied from a side of the cavity. The plate may include multiple thin plates that are laminated and, thus, it is possible to prevent the plate from being warped.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description will now be given of embodiments of the present invention with reference to the accompanying drawings.

First Embodiment

FIG. 4Ais an enlarged view of a cavity portion of a carrier used in an apparatus for manufacturing a semiconductor device in accordance with a first embodiment of the present invention, andFIG. 4Bis a cross-sectional view of a part of the apparatus in accordance with a first embodiment of the present invention.FIG. 5Ais a plan view of a plate used in the first embodiment of the present invention, andFIG. 5Bis a cross-sectional view of the plate. An apparatus for manufacturing a semiconductor device includes the upper mold21, the lower mold22and a plate30. The upper mold21has a runner23, and the upper mold21and the lower mold22do not have cavities. The apparatus40is equipped with a press mechanism (not shown) that clamps and opens the molds21and22. The semiconductor device has electrode pads on a surface of the substrate27sealed with resin.

The plate30is inserted into the upper mold21and the lower mold22, and includes a cavity31that define the outer shape and thickness of the resin sealing portions and a gate32for guiding resin to the cavity31. The plate30may be made of, for example, stainless steel, titanium or nickel alloy. The cavity31is formed to have an opening area that becomes greater (varies) towards the substrate27in the thickness direction of the plate30.

The gate32has a dent (pocket) in the thickness direction of the plate30. The dent forms an opening area that becomes narrower (varies) towards the substrate27in the thickness direction of the plate30. The gate32is provided in a position that allows resin to be injected from a side of the cavity31. At the time of gate break, the gate32causes cracks to originate from a line defined by crossing of the pockets and the side surfaces of the mold. This reduces the probability of a gate residual that protrudes from the upper surface of the molded body.

Referring toFIGS. 5A and 5B, the manufacturing apparatus includes a plate30having multiple cavities31with multiple gates32. The upper mold21of such apparatus would necessarily have multiple runners23formed therein to provide the resin to the cavities31and the gates32.

FIGS. 6A through 6Fillustrate a method for a resin sealing process for a semiconductor device in accordance with the first embodiment of the present invention. Referring toFIG. 6A, the substrate27on which the semiconductor chip is mounted is placed in the substrate holding portion while the upper mold21and the lower mold22are separated. The plate30is disposed between the upper mold21and lower mold22over the substrate27. Referring toFIG. 6B, melted resin is supplied via the supply port24formed on the lower mold22, passes through the runner23and the gate32formed on the plate30, and is then injected into the cavity31. The resin injected into the cavity31is held for a few minutes in order to cure the resin. Referring toFIG. 6C, the resin sealing portion35is formed into the same shape as that of the cavity31. Then, as shown inFIG. 6D, the lower mold22is moved down and the upper mold21is detached from the molded body. As shown inFIG. 6E, unnecessary resin36is removed and the plate30is taken away. In this manner, the semiconductor device with the semiconductor chip being sealed with resin in accordance with the first embodiment of the present invention is obtained, as shown inFIG. 6F.

To manufacture another semiconductor device with a resin sealing portion having a different outer size, the manufacturer need only replace the plate with another plate while the same upper mold21lower mold22are used. The above-mentioned process with another plate results in a semiconductor device with the resin sealing portion having a different outer size. Thus, conventional mold equipment having the upper mold21and lower mold22can be utilized for implementation of the present invention.

According to the first embodiment of the present invention, the plate30is provided with cavities31in which resin is injected and cured for shaping into the molded bodies and gates32for guiding the resin to the cavities31. It is thus possible to provide semiconductor devices that do not have any mold burrs (resin burrs) remaining on the upper surfaces of the molded bodies. Even if a gate residual exists, it is unlikely to protrude from the upper surface of the molded body, thereby providing semiconductor devices which, after gate break, will have a uniform height. Further, the semiconductor device does not have any exposed portion even after the gate is undercut. Additionally, the plate can be reused, thereby reducing the production cost. Additionally, the molds of the present invention are simpler than conventional molds and can be reused for semiconductor devices having different sizes by only providing a different plate30.

Second Embodiment

A second embodiment of the present invention will now be described with reference toFIGS. 7A and 7B.FIG. 7Ais a plan view of a plate in accordance with the second embodiment, andFIG. 7Bis a cross-sectional view thereof. A plate130is inserted between the upper mold21and the lower mold22, and includes a resin film132positioned so as to contact a plate body131and electrodes provided on the substrate. The use of the soft resin film132absorbs a roughness due to the presence of interconnection lines on the substrate and, by adapting to the uneven surface of the electrodes on the substrate, prevents resin from being leaked thereto. The plate body131and the resin film132form cavities133that define the outer shape and thickness of the resin sealing portion. The cavities133are formed so as to have an opening area that becomes greater (varies) towards the substrate (not shown) in the thickness of the plate body131.

Further, the plate body131is provided with gates134for guiding resin into the cavities133. The gates134have dents in the thickness direction of the plate body131so as to have an opening area that becomes narrower (varies) in the thickness direction thereof. The gates134are provided at positions that allow resin to be injected from sides of the cavities133.

The resin film132is fixed, by viscoelastic or adhesive bonding, to a side of the plate body131that contacts electrodes on the substrate. If the resin film132is not fixed to the plate body131by viscoelastic or adhesive bonding beforehand, positioning pins may be used. Positioning pins penetrate through holes formed in the resin film132and the plate body131, which are laminated and positioned in relation to the upper mold21and the lower mold22for receiving the positioning pins.

Third Embodiment

A third embodiment of the present invention will now be described with reference toFIGS. 8A,8B and9.FIG. 8Ais a plan view of a plate230in accordance with the third embodiment, andFIG. 8Bis a cross-sectional view thereof. The plate230is inserted between the upper mold21and the lower mold22. Multiple thin plates, which include an uppermost plate231and an intermediate plate232, are laminated and locally joined by spot welding to prevent the plate230from warping.

Further, a resin film233is attached to the surface of the intermediate plate232that contacts the electrodes on the substrate. Cavities234for defining the outer shape and thickness of the resin sealing portions are provided in all of the multiple thin plates, e.g., the uppermost plate231, the intermediate plate232and the resin film233. Gates235for guiding resin to the cavities234are provided in only the uppermost plate231among the multiple thin plates and at positions that allow resin to be injected from the sides of the cavities234. The resin film233is fixed, by viscoelastic or adhesive bonding, to the side of the intermediate plate232towards the electrodes on the substrate.

Instead of fixing the resin film233to the intermediate plate232by viscoelastic or adhesive bonding beforehand, positioning pins may be used. The positioning pins penetrate through guide holes236formed in the uppermost plate231, the intermediate plate232and the resin film233, the guide holes236being laminated and positioned on the plate230to allow penetration thereof by the positioning pins on either or both of the upper mold21and the lower mold22.

FIG. 9shows an example in accordance with the third embodiment of the present invention in which the plate230is fixed to the upper mold21and the lower mold22by guide pins237and238, which are the positioning pins. The plate230is made up of multiple thin plates, each of which has guide holes236through which the guide pins237and238are inserted. The multiple thin plates can be positioned to the upper mold21and the lower mold22by using the guide pins237and238, without fixing these thin plates by adhesion or the like, while the seal resin240is applied through the gates235and the cavities234.

Fourth Embodiment

A fourth embodiment of the present invention will now be described.FIG. 10shows an exemplary structure in accordance with the fourth embodiment of the present invention in which an outer frame is attached to the plate.FIG. 11Ais a plan view of a plate330in accordance with the fourth embodiment of the present invention,FIG. 11Bis a cross-sectional view taken along a line A-A shown inFIG. 11A, andFIG. 11Cis a cross-sectional view taken along a line B-B shown therein.

Recently, semiconductor packages have become thinner and a thinner plate is required. As the plate becomes thinner, the rigidity of the plate is degraded and deformed during use. Taking the above into consideration, an outer frame335is attached to the plate330along the circumference thereof. The outer frame335makes it possible to use a plate having a small rigidity and thin seal resin. As shown inFIGS. 11A to 11C, the plate330is provided multiple supply ports331aand331bfor supplying melted seal resin240from the lower mold22. Cavities332a,332b,333aand333bare symmetrically arranged across the multiple supply ports331aand331b. Gates334are provided in positions that allow the seal resin240to be injected from sides of the cavities332a,332b,333aand333b. Further, portions of the plate330that contact the seal resin240are coated with fluorocarbon resin or plated with gold for ease of removal of the resin.

In accordance with the manufacturing method for semiconductor devices described above, it is possible to eliminate contamination of the electrode pads caused by oil or particles such as resin burrs. It is also possible to prevent occurrence of resin burrs on the upper surface of the molded body and improve production yield.

The present invention is not limited to the specifically described embodiments, but includes various variations and modifications within the scope of the present invention as defined by the claims below and their equivalents.