JPH09148481A - Semiconductor device, and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a BGA-type semiconductor device where cracks do not occur in the package, at the time of solder reflow, and to surely form a bump electrode at manufacture of a semiconductor device. SOLUTION: This semiconductor device has a substrate 1 having wiring and besides a plurality of external terminal electrodes at the rear, a semiconductor chip 3 fixed to the main face of the board 1 by paste 2, a through vent hole 5 provided at the substrate section corresponding to the fixed region of the semiconductor chip 3, a connection means for electrically connecting the electrode of the semiconductor chip 3 with the wiring of the board 1, and a resin package 10 for covering a semiconductor chip 3, etc., being attached to the main surface side of the board 1. In this case, the vent hole 10 pierces the board, and reaches at least the inside of the paste 2 to fix the semiconductor chip 3 to the board 1. The vent hole 10 reaches the inside of the cavity 11 provided at the substrate part facing the semiconductor chip 3. An external terminal electrode becomes a solder bump electrode 9, and constitutes a BGA- type semiconductor device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and its manufacturing method, and more particularly to a BGA (Ball Grid Array) type semiconductor device and its manufacturing method.

[0002]

BG as one of surface mount semiconductor devices
A-type semiconductor devices are known. Regarding the BGA type semiconductor device, for example, “Electronic Materials” 1994 issued by Industrial Research Committee
September issue, published on September 1, the same year, P37-P43.

In this document, BT (Bismalemide Triazi
ne) A BGA type semiconductor device in which an LSI chip is fixed to the main surface of an epoxy substrate and solder balls are provided on the back surface is described. The BGA type semiconductor device has a structure in which the electrodes of the LSI chip and the wiring of the substrate are connected by wires, and the LSI chip and the wires are covered with a molding resin. In addition, this BGA type semiconductor device has a through hole (thermal via) for heat dissipation and ground penetrating the substrate in a substrate region facing the LSI chip.

Further, a BGA type semiconductor device in which a vent hole is provided on a substrate as a measure against reflow resistance is commercially available ("1M Synchronous DRAM" manufactured by Hitachi, Ltd.).

[0005]

The surface mount semiconductor device of the resin package type employs a method of reflowing the solder previously provided on the electrodes when mounting on the mounting substrate. In this case, the moisture in the resin that forms the package and the moisture contained in the paste (adhesive) that fixes the semiconductor chip to the substrate become steam due to the heat during reflow, which causes cracks in the package and moisture resistance. It is known that sex decreases.

Also in the BGA type semiconductor device, a vent hole penetrating the substrate is provided as shown in a part of FIG. 8 in order to prevent the reflow resistance.

However, it has been clarified by the present inventor that such a BGA type semiconductor device has the following problems in its manufacture.

FIG. 8 is a diagram in the middle of manufacturing a BGA type semiconductor device, in which a semiconductor chip 3 is fixed to the main surface of a substrate 1 via a paste 2, and electrodes (not shown) of the semiconductor chip 3 and wiring (not shown) of the substrate 1 are provided. It is the figure which connected with with the wire 4.
Further, thereafter, a package made of resin is provided on the main surface of the substrate 1 so as to cover the semiconductor chip 2 and the like, and then bump electrodes made of solder are provided on the back surface of the substrate 1 to form a BGA. Type semiconductor device.

Further, in the center of the substrate area facing the semiconductor chip 2, there is a vent hole 5 for reflow resistance.
Are provided so as to penetrate the substrate 1.

Therefore, when the semiconductor chip 3 is fixed to the main surface of the substrate 1 with the paste 2, the paste 2 flows out from the vent hole 5 and stains the back surface of the substrate 1 as shown in FIG. Contamination of the paste on the back surface of the substrate 1 leads to contamination of the surface of the base electrode 6 for forming the bump electrode, and the bump electrode may not be formed when the bump electrode is formed.

Further, as shown in FIG. 10, the paste 2 is clogged in the vent hole 5, and during the solder reflow of the BGA type semiconductor device, the vent hole 5 does not function as a water vapor escape passage for reflow resistance countermeasures. The package is cracked and the moisture resistance deteriorates.

An object of the present invention is to provide a BGA type semiconductor device in which a crack does not occur in a package during solder reflow mounting, and a method for manufacturing the same.

Another object of the present invention is to provide a method of manufacturing a BGA type semiconductor device capable of reliably forming bump electrodes.

The above and other objects and novel features of the present invention will be apparent from the description of the present specification and the accompanying drawings.

[0015]

The following is a brief description of an outline of typical inventions disclosed in the present application.

(1) A substrate having wiring and a plurality of external terminal electrodes on the back surface, a semiconductor chip fixed to the main surface of the substrate by a paste, and a substrate portion corresponding to a fixing region of the semiconductor chip. A semiconductor having a penetrating vent hole provided, a connecting means for electrically connecting the electrode of the semiconductor chip and the wiring of the substrate, and a resin package mounted on the main surface side of the substrate and covering the semiconductor chip and the like. In the device, the vent hole penetrates the substrate and reaches at least a paste that fixes the semiconductor chip to the substrate. The vent hole reaches the paste in the recess provided in the substrate portion facing the semiconductor chip. The external terminal electrodes serve as solder bump electrodes and form a ball grid array type semiconductor device.

(2) In the structure of the above-mentioned means (1), the vent hole reaches at least the paste in the recess provided in the substrate region corresponding to a part of the peripheral edge of the semiconductor chip.

(3) A step of fixing a semiconductor chip to the main surface of a substrate having wiring and having a plurality of external terminal electrodes on the back surface by a paste, and electrically connecting the electrode of the semiconductor chip and the wiring of the substrate by a wire. Connecting to
A step of forming a resin package on the main surface side of the substrate so as to cover the semiconductor chip and the like, and a vent hole in the substrate so as to reach the paste from the back surface side of the substrate. A recess is formed in a part of the substrate to receive the paste, and then the semiconductor chip is fixed. The vent hole is formed so as to reach the paste in the depression. Solder bump electrodes are formed as external terminal electrodes on the back surface of the substrate to manufacture a ball grid array type semiconductor device.

According to the above-mentioned means (1), since the back surface of the substrate of the ball grid array type semiconductor device is provided with the vent hole whose tip faces the inside of the paste for fixing the semiconductor chip to the substrate, the solder is formed. When the bump electrode is reflow-mounted and mounted, the vent hole functions as an escape path for water vapor generated in the paste to the outside, so that the package does not crack.

According to the above-mentioned means (2), since the vent hole reaches at least the paste in the recess provided in the substrate region corresponding to a part of the peripheral edge of the semiconductor chip, the paste It also serves as a vent hole that reliably guides the water vapor generated in the package to the outside.

According to the above-mentioned means (3), in the manufacture of the ball grid array type semiconductor device, after forming the depression into which the paste is inserted in a part of the main surface of the substrate, the semiconductor chip is fixed to the main surface of the substrate by the paste. However, since the vent hole is formed so as to reach the paste in the recess after wire bonding and resin packaging, the back surface of the substrate is not contaminated by the paste, and the vent hole is not clogged by the paste.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In all the drawings for describing the embodiments of the present invention, components having the same functions are denoted by the same reference numerals, and their repeated description will be omitted.

(Embodiment 1) FIG. 1 is a sectional view showing the outline of a BGA type semiconductor device which is an embodiment (embodiment 1) of the present invention, and FIGS. 2 to 4 are BGA type semiconductor devices of this embodiment 1. FIG. 2 is a diagram showing each step in the manufacturing method of FIG. 2, FIG. 2 is a sectional view showing a substrate used in the manufacturing method of the BGA type semiconductor device, and FIG. 3 is a sectional view showing a substrate after chip bonding, wire bonding, and transfer molding. 4A and 4B are cross-sectional views showing a substrate in which a vent hole is formed in the substrate.

As shown in FIG. 1, the BGA type semiconductor device according to the first embodiment has a flat substrate 1 in appearance and a substantially rectangular package formed on the main surface (upper surface) of the substrate 1. 10 and an external terminal electrode composed of a plurality of solder bump electrodes 9 arranged in an array on the back surface (lower surface) of the substrate 1.

The substrate 1 is made of a BT epoxy substrate or the like, and although not shown, wiring is provided on the main surface thereof and solder bump electrodes 9 are formed in an array on the back surface. The solder bump electrode 9 and the wiring on the main surface of the substrate are electrically connected to each other via a conductor filled in a through hole (not shown).

Further, a depression 11 having a depth of, for example, about 0.3 mm is provided in the center of the main surface of the substrate 1.

A semiconductor chip 3 is fixed to the center of the main surface of the substrate 1 with a paste 2. The entire lower surface of the semiconductor chip 3 is fixed to the substrate 1 via the paste 2, and the paste 2 also enters the depression 11. In FIG. 1, the paste 2 other than the recess 11 is shown by a thick line (same in the following figures).

The back surface (lower surface) of the substrate 1 is
A vent hole 5 whose front end faces the paste 2 in the depression 11 from the side is formed. As will be described later, the vent hole 5 is provided from the back surface side of the substrate 1 after fixing the semiconductor chip 3 to the substrate 1. Therefore, paste 2
Does not contaminate the back surface of the substrate 1 nor does the paste 2 block the vent hole 5.

An electrode (not shown) of the semiconductor chip 3 fixed to the main surface of the substrate 1 and each wiring (not shown) on the main surface of the substrate 1 are electrically connected to each other, for example, a conductive wire 4
Are electrically connected via

The package 10 seals the semiconductor chip 3 and the wires 4.

Next, a method of manufacturing (assembling) the BGA type semiconductor device of the first embodiment will be described.

As shown in FIG. 2, the substrate 1 is first prepared. The substrate 1 is made of, for example, a BT epoxy substrate and the like, and although not shown in the drawings, wiring is provided on the main surface thereof and a base electrode for forming solder bump electrodes in an array is provided on the back surface thereof. . The base electrode and the wiring on the main surface of the substrate are electrically connected via a conductor filled in a through hole (not shown).

Next, a recess 11 smaller than the semiconductor chip 3 fixed to the main surface of the substrate 1 is formed in the center of the main surface of the substrate 1. A vent hole is later formed in the recess 11 from the back surface of the substrate 1 by a drill. At this time, the tip of the drill should not damage the semiconductor chip.
It is provided to ensure that the tip of the vent hole faces the paste. Therefore, the depth of the recess 11 may be appropriately determined within the range that satisfies the above condition. For example,
The recess 11 has a depth of about 0.3 mm.

Next, as shown in FIG. 3, the semiconductor chip 3 is fixed to the main surface of the substrate 1 via the paste 2. Although only a part of the paste 2 is illustrated, the paste 2 extends over the entire back surface of the semiconductor chip 3.

Next, the electrodes (not shown) of the semiconductor chip 3 and the wiring (not shown) on the main surface of the substrate 1 are electrically connected by the wires 4. Other electrical connection means may be used to connect the electrodes of the semiconductor chip 3 to the wiring.

Next, the package 10 made of resin is formed on the main surface of the substrate 1 by a conventional transfer mold. The package 10 seals the semiconductor chip 3, the wire 4, and the like.

Next, as shown in FIG. 4, a vent hole 5 is formed from the back surface of the substrate 1 by a drill. At this time, the tip of the drill is shallowly inserted into the paste 2 to form the vent hole 5 so as not to damage the semiconductor chip 3 with the tip of the drill.

Next, the solder bump electrode 9 is formed on the back surface of the substrate 1.
Are formed to manufacture a BGA type semiconductor device as shown in FIG.

The solder bump electrode 9 is formed on a base electrode (not shown) on the back surface of the substrate 1. Since the surface of the base electrode is not contaminated by the paste, the solder bump electrode 9 is surely attached to the base electrode. It is formed.

In the manufacture of the BGA type semiconductor device of the first embodiment, the vent hole 5 is not provided in the substrate 1 when the semiconductor chip 3 is fixed to the main surface of the substrate 1 via the paste 2. The back surface of the substrate 1 is not contaminated. Therefore, the base electrode on the back surface of the substrate 1 is not contaminated by the paste, and the solder bump electrode 9
At the time of forming, the solder bump electrode 9 can be reliably formed on the base electrode, and the yield of solder bump electrode formation is improved.

In the BGA type semiconductor device according to the first embodiment, the vent hole 5 provided in the substrate 1 is formed after the semiconductor chip 3 is fixed to the substrate 1 via the paste 2, so that the paste 2 is clogged with the vent. It does not block Hall 5. Therefore, at the time of reflow mounting, even if the moisture contained in the paste 2 on the lower surface side of the semiconductor chip 3 becomes steam due to the heat at the time of mounting, this steam will pass through the vent hole 5 to the outside, which is caused by the steam. Package cracks will not occur and the reliability of mounting will increase.

(Embodiment 2) FIG. 5 is a sectional view showing a part of a BGA type semiconductor device according to another embodiment (embodiment 2) of the present invention, and FIG. 6 shows a BGA type semiconductor device of this embodiment 2. It is a top view showing a substrate used for manufacture and a semiconductor chip fixed to the substrate.

In the BGA type semiconductor device of the second embodiment,
As shown in FIGS. 5 and 6, the recess 11 provided on the main surface of the substrate 1 is a part of the peripheral edge of the semiconductor chip 3, that is, 4
It is provided so as to partially cover each central portion of the side.
Then, in the manufacture of the BGA type semiconductor device, the vent hole 5 is formed from the rear surface portion of the substrate 1 corresponding to the recess 11.
Are formed after the formation of the package 10.

In the substrate 1 of FIG. 6, the recess 11 is provided and the semiconductor chip 3 is fixed, but the vent hole 5 is not formed yet.

In the manufacture of the BGA type semiconductor device of the second embodiment, since the part forming the vent hole 5 is a part separated from the semiconductor chip 3, the semiconductor chip 3 is damaged even if a deep drill is inserted. Without doing so, the margin of work for opening the vent hole 5 is increased, and the workability is improved.

Also in the case of this BGA type semiconductor device, the vent holes 5 provided at four places reach the paste 2 portion for fixing the semiconductor chip 3 and the substrate 1, and the vent holes 5 are Since it reaches the resin portion that penetrates the paste 2 and forms the package 10,
When the BGA type semiconductor device is reflow-mounted, even if the moisture contained in the resin or paste becomes water vapor due to the heat at the time of mounting, the water vapor passes through each vent hole 5 to the outside, so that the package crack does not occur. .

Even when the BGA type semiconductor device of the second embodiment is manufactured, since the vent hole 5 is not provided in the substrate 1 when the semiconductor chip 3 is fixed, there is no contamination by the paste on the back surface of the substrate 1.

(Embodiment 3) FIG. 7 is a plan view showing a substrate used for manufacturing a BGA type semiconductor device according to another embodiment (Embodiment 3) of the present invention and a semiconductor chip fixed to the substrate. .

In the BGA type semiconductor device of the third embodiment,
In the manufacturing, as shown in FIG. 7, the recess 11 provided in the main surface of the substrate 1 is a part of the peripheral edge of the semiconductor chip 3,
That is, the rectangular semiconductor chip 3 is provided so as to partially cover the portions corresponding to the respective vertices. In the first embodiment, the recess 11 has an elliptical shape, and although not shown, the semiconductor chip 3 is formed on the main surface of the substrate 1 by the paste 2.
After fixing, wire bonding, packaging,
A vent hole 5 is formed by a drill so as to reach the recess 11 from the back surface of the substrate 1.

In the manufacture of the BGA type semiconductor device of the third embodiment, as in the case of the second embodiment, since the part where the vent hole 5 is formed is the part which is separated from the semiconductor chip 3, it is deep. Even if a drill is inserted, the semiconductor chip 3 is not damaged, the margin of work for opening the vent hole 5 is increased, and workability is improved.

Also in the case of the BGA type semiconductor device of the third embodiment, the vent holes 5 provided at four places reach the paste 2 portion for fixing the semiconductor chip 3 and the substrate 1, and Since the vent hole 5 reaches the resin portion which penetrates the paste 2 and forms the package 10, the moisture contained in the resin and the paste is vaporized by the heat at the time of reflow mounting of the BGA type semiconductor device. However, since this water vapor passes through each vent hole 5 to the outside, package cracks do not occur.

Even when the BGA type semiconductor device of the third embodiment is manufactured, since the vent hole 5 is not provided in the substrate 1 when the semiconductor chip 3 is fixed, the paste on the back surface of the substrate 1 is not contaminated.

Although the invention made by the inventor has been specifically described based on the embodiment, the invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention. Needless to say. The present invention can be applied to BGAs having other structures.

[0055]

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

(1) On the back surface of the substrate of the ball grid array type semiconductor device, there is provided a vent hole whose front end faces in the paste for fixing the semiconductor chip to the substrate. Therefore, the solder bump electrode is reflowed and mounted. In this case, the vent hole functions as an escape path for water vapor generated in the paste to the outside, so that the package does not crack.

(2) In the manufacture of a ball grid array type semiconductor device, after forming a recess into which paste is inserted in a part of the main surface of the substrate, the semiconductor chip is fixed to the main surface of the substrate by the paste, wire bonding, resin package Since the vent hole is formed so as to reach the paste in the recess after the paste is formed, the back surface of the substrate is not contaminated by the paste and the vent hole is not clogged with the paste. Therefore, the reliability of the solder bump electrode formed on the back surface of the substrate is increased, and the manufacturing yield of the solder bump electrode is improved. In addition, package cracks are less likely to occur during reflow and the mounting reliability is high.
It becomes a GA type semiconductor device.

[Brief description of the drawings]

FIG. 1 is a BG that is an embodiment (Embodiment 1) of the present invention.
It is sectional drawing which shows the outline of an A-type semiconductor device.

FIG. 2 is a cross-sectional view showing a substrate used in the manufacturing method of the BGA type semiconductor device of the first embodiment.

FIG. 3 is a plan view showing a method of manufacturing a BGA type semiconductor device according to the first embodiment, in which chip bonding, wire bonding,
It is sectional drawing which shows the board | substrate which the transfer mold completed.

FIG. 4 is a cross-sectional view showing a substrate in which a vent hole is formed in the substrate in the method for manufacturing the BGA type semiconductor device according to the first embodiment.

FIG. 5 is another embodiment (second embodiment) of the present invention, B.
It is a sectional view showing a part of GA type semiconductor device.

FIG. 6 is a plan view showing a substrate used for manufacturing the BGA type semiconductor device of the second embodiment and a semiconductor chip fixed to the substrate.

FIG. 7 shows another embodiment (Embodiment 3) B of the present invention.
It is a top view showing a substrate used for manufacturing a GA type semiconductor device, and a semiconductor chip fixed to the substrate.

FIG. 8 is a cross-sectional view showing a part of a conventional BGA type semiconductor device.

FIG. 9 is a schematic cross-sectional view showing a state in which a paste has flowed from a vent hole of a substrate to the back surface of the substrate in a conventional BGA type semiconductor device.

FIG. 10 is a schematic cross-sectional view showing a state in which a vent hole of a substrate is blocked with a paste in a conventional BGA type semiconductor device.

[Explanation of symbols]

1 ... Substrate, 2 ... Paste, 3 ... Semiconductor chip, 4 ... Wire, 5 ... Vent hole, 6 ... Base electrode, 9 ... Solder bump electrode, 10 ... Package, 11 ... Dimple.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Issei Suzuki, 5-22-1 Kamisuihoncho, Kodaira-shi, Tokyo Inside Hitachi Microcomputer System Co., Ltd. (72) Inventor, Daiki Ishimura 145 Nakajima, Nanae, Kameda-gun, Hokkaido Address inside Hitachi Hokkai Semiconductor Co., Ltd.

Claims (7)

[Claims] 1. A substrate having wiring and a plurality of external terminal electrodes on the back surface, a semiconductor chip fixed to the main surface of the substrate by a paste, and a substrate portion corresponding to a fixing region of the semiconductor chip. And a resin package mounted on the main surface side of the substrate to cover the semiconductor chip and the like. The semiconductor device, wherein the vent hole penetrates the substrate and reaches at least a paste for fixing the semiconductor chip to the substrate. 2. The semiconductor device according to claim 1, wherein the vent hole reaches the inside of the paste in the recess provided in the substrate portion facing the semiconductor chip. 3. The semiconductor device according to claim 1, wherein the vent hole reaches at least the paste in a recess provided in a substrate region corresponding to a part of a peripheral edge of the semiconductor chip. 4. The semiconductor device according to claim 1, wherein the external terminal electrode serves as a solder bump electrode to form a ball grid array type semiconductor device. 5. A step of fixing a semiconductor chip to the main surface of a substrate having wiring and having a plurality of external terminal electrodes on the back surface by a paste, and electrically connecting the electrode of the semiconductor chip and the wiring of the substrate. A step of forming a resin package on the main surface side of the substrate so as to cover the semiconductor chip and the like, and forming a vent hole in the substrate so as to reach the paste from the back surface side of the substrate. And a method for manufacturing a semiconductor device. 6. The semiconductor chip is fixed after forming a recess into which the paste is inserted in a part of the substrate, and then a vent hole is formed so as to reach the paste in the recess. A method for manufacturing a semiconductor device as described above. 7. The semiconductor device manufacturing method according to claim 5, wherein solder bump electrodes are formed as external terminal electrodes on the back surface of the substrate to manufacture a ball grid array type semiconductor device. Method.