JP2002176123A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure of a semiconductor device for realizing a one-side electrode substrate at low cost by using a polyimide film substrate 30 while a small package with a small area of mounting is obtained. SOLUTION: A third narrow through hole 36 with a length longer than one side of a transistor chip (T) is formed on a polyimide substrate 30. Ag paste is caused to flow and the transistor chip (T) is fixed so that a third electrode 33 is formed more inside the transistor chip (T), and a greatly small and low- cost structure of the semiconductor device can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device,
In particular, the present invention relates to a single-sided electrode type semiconductor device realizing a thin mounting structure.

[0002]

2. Description of the Related Art As a conventional general semiconductor device, there is a package type semiconductor device sealed by transfer molding using a lead frame. This semiconductor device
As shown in FIG. 4, it is mounted on a printed circuit board PS.

In this package type semiconductor device, the periphery of a semiconductor chip 2 is covered with a resin layer 3, and lead terminals 4 for external connection are led out from the side of the resin layer 3.

However, this package type semiconductor device 1 has
The lead terminals 4 were outside the resin layer 3, and the overall size was large, and the size, thickness and weight were not satisfied.

[0005] Therefore, various companies have developed various structures in order to realize miniaturization, thinning and weight reduction in competition, and recently, a wafer scale CSP called a CSP (chip size package), which is equivalent to the chip size, has been developed. Alternatively, a CSP having a size slightly larger than the chip size has been developed.

FIG. 5 shows a CSP that employs a glass epoxy substrate 5 as a support substrate and is slightly larger than the chip size.
6 shows a semiconductor device having an outer shape of No. 6.

A first electrode 7, a second electrode 8, and a die pad 9 are formed on the surface of the glass epoxy substrate 5, and a first back electrode 10 and a second back electrode 11 are formed on the back surface.
Are formed. And, through the through hole TH,
The first electrode 7 and the first back electrode 10 are electrically connected, and the second electrode 8 and the second back electrode 11 are electrically connected. A transistor chip T is fixed to the die pad 9,
The emitter electrode of the transistor and the first electrode 7 are connected via a thin metal wire 12, and the base electrode of the transistor and the second electrode 8 are connected via the thin metal wire 12. Further, a resin layer 13 is provided on the glass epoxy substrate 5 so as to cover the transistor chip T.

Although the above-mentioned CSP 6 employs the glass epoxy substrate 5, unlike the wafer-scale CSP, the extending structure from the chip T to the backside electrodes 10 and 11 for external connection is simple and can be manufactured at low cost. Having.

The CSP 6 is mounted on a printed circuit board PS as shown in FIG. The printed circuit board PS is provided with electrodes and wiring constituting an electric circuit.
6. The package type semiconductor device 1, the chip resistor CR or the chip capacitor CC and the like are electrically connected and fixed.

Next, a method of manufacturing the semiconductor device of the CSP 6 will be described with reference to FIG.

First, a glass epoxy substrate 5 is prepared as a base material (supporting substrate), and C
The u foils 15 and 16 are crimped. (See FIG. 6A above.) Subsequently, the first electrode 7, the second electrode 8, the die pad 9, and the first
Cu corresponding to the back electrode 10 and the second back electrode 11
The foils 15 and 16 are coated with an etching-resistant resist 17, and the Cu foils 15 and 16 are patterned. The patterning may be performed separately on the front and back sides (see FIG. 6B).
A hole for H is formed in the glass epoxy substrate, and the hole is plated to form a through hole TH. Through hole TH, first electrode 7 and first back electrode 10 are electrically connected, and second electrode 8 and second back electrode 11 are electrically connected. (See FIG. 6C above.) Further, although omitted in the drawing, the first electrode 7 and the second electrode
The electrode 8 is plated with Au, and the die pad 9 serving as a die bonding post is plated with Au, and the transistor chip T is die-bonded.

Finally, the emitter electrode of the transistor chip T and the first electrode 7, and the base electrode of the transistor chip T and the second electrode 8 are connected via a thin metal wire 12 and covered with a resin layer 13. (See FIG. 6D above.) By the above manufacturing method, C
An SP type semiconductor device is completed. This manufacturing method is the same even when a flexible sheet is used as the support substrate.

Since the semiconductor device manufactured by the above-described manufacturing method has a double-sided electrode structure, and the glass epoxy substrate 5 is thick, the semiconductor device becomes thick as a circuit element, and there is a limit in reducing the size, thickness and weight. Furthermore, a through-hole forming step for connecting electrodes on both surfaces is indispensable for a glass epoxy substrate or a ceramic substrate, and the manufacturing process becomes long, which is not suitable for mass production.

In order to solve the above-mentioned problems of the semiconductor device having the double-sided electrode structure, the following semiconductor device having the single-sided electrode structure has been proposed.

Referring to FIGS. 7 and 8, a semiconductor device having this single-sided electrode structure will be described. 7A is a top view, FIG. 7B is a back view, and FIG. 8 is a cross-sectional view, in which a resin layer for molding is omitted.

As shown in FIG. 7, a first electrode 21 and a second electrode 2
2 and a third electrode 23 serving as a die pad are formed. The polyimide film substrate 20 on the first electrode 21 and the second electrode 22 has a first through hole 24 and a second through hole 25 smaller than the first electrode 21 and the second electrode 22. A first electrode 21 and a second electrode 2
2, the surface on the polyimide film substrate 20 side is exposed. Further, a third through hole 26 is also provided in the polyimide film substrate 20 on the third electrode 23,
The central part of the upper surface of the third electrode 23 is exposed. The exposed upper surface of the third electrode 23 functions as a die pad,
The transistor chip T is fixed to this portion, the emitter electrode of the transistor chip T and the first electrode 21 are connected via a thin metal wire 27, and the base electrode of the transistor chip T and the second electrode 22 are connected via a thin metal wire 27. Connected. Further, as shown in FIG. 8, a resin layer 28 is provided on the polyimide film substrate 20 so as to cover the transistor chip T.

In the above-described conventional semiconductor device having a single-sided electrode structure, the transistor chip T is directly fixed to the upper surface of the third electrode 23. There is a great advantage that the thickness of 7, 8, and 9 can be reduced, and a thin semiconductor device can be realized.

[0018]

However, even a semiconductor device having a single-sided electrode structure has many disadvantages.

First, on the upper surface of the third electrode 23 to which the transistor chip T is directly fixed, a third through hole having a margin which is at least larger than the transistor chip T and has a margin for covering the chip mounting position accuracy is provided. Hole 2
6 need to be provided. For this purpose, the third electrode 2
3 is formed larger than the third through hole 26, there is a problem that it is considerably larger than the lower surface electrode connected to the die pad in the case of the double-sided electrode structure.

Second, a first electrode 21 and a second electrode 22
The first through-hole 24 and the second through-hole 25 provided on the upper surface of the first electrode also need to be at least large enough to accommodate a capillary used for bonding in order to bond the fine metal wire 27. 21, the second electrode 22 also needs to be formed quite large.

Third, when a completed semiconductor device is mounted on a printed circuit board or the like, in either the single-sided electrode structure or the double-sided electrode structure, a fixed distance is set between the lower surface electrodes to prevent a short circuit due to a brazing material such as solder. Must be secured. For this reason, the semiconductor device having the single-sided electrode structure is superior in thickness to the double-sided electrode structure, but loses in the occupied area to the double-sided electrode structure.

[0022]

SUMMARY OF THE INVENTION The present invention has been made in view of the various problems described above, and comprises a semiconductor chip fixed to an upper surface of an insulating substrate and a die lower electrode provided on a lower surface of the insulating substrate. A through-hole provided in the insulating substrate; and a conductive paste filled in the through-hole and electrically connecting the semiconductor chip and the die lower surface electrode, wherein the width of the through-hole is wider than one side of the semiconductor chip. The semiconductor device is characterized in that it is formed to be narrow, the length of the through hole is made longer than one side of the semiconductor chip, and one end of the through hole extends at least to the outside of the semiconductor chip.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor device according to the present invention will be described with reference to FIGS. FIG. 1A is a top view of the semiconductor device of the present invention, and FIG. 1B is a rear view of the semiconductor device of the present invention, in which a resin layer for molding is omitted. FIG.
Shows a cross-sectional view of the semiconductor device of the present invention.

As shown in FIG. 1, a first electrode 31, a second electrode 32 and a third electrode 33 (substrate having a thickness of about 20 μm) are provided on the back surface of the polyimide film substrate 30 (substrate having a thickness of about 50 μm). ) Is formed. And the first electrode 3
First, a first through hole 34 and a second through hole 35 smaller than the first electrode 31 and the second electrode 32 are provided in the polyimide film substrate 30 on the second electrode 32.
The upper surface of the electrode 31 and the second electrode 32, that is, the surface on the polyimide film substrate 30 side is exposed.

Further, a third through hole 36 is also provided in the polyimide film substrate 30 on the third electrode 33 along the center line of the transistor chip T, and the central portion of the upper surface of the third electrode 33 is horizontally elongated. It is exposed like a slit. The Ag paste 38 flows into the third through hole 36 exposed in a horizontally elongated slit shape until a small amount overflows onto the polyimide film substrate 30, and the transistor chip T is fixed thereon.

Subsequently, the emitter electrode of the transistor chip T and the first electrode 31 are connected via a bonding wire 37, and the base electrode of the transistor chip T and the second electrode 32 are connected via the bonding wire 37. . Note that Ni is applied to the surfaces of the first electrode 31 and the second electrode 32 so that the bonding wire 37 can be fixed thereto.
Finish plating of 0.5 to 1 μm of plating and 0.3 μm of gold plating is performed thereon.

Further, as shown in FIG. 2, a resin layer 39 is provided on the polyimide film substrate 30 so as to cover the transistor chip T.

The present invention is characterized by the third through hole 36. That is, the third through hole 36 is formed in the center of the upper surface of the third electrode 33 in a slit shape that is horizontally long in the longitudinal direction of the third electrode 33. The length of the third through-hole 36 protrudes from both sides of the transistor chip T fixed thereon, and the width is smaller than one side of the transistor chip T.

An Ag paste 38 is formed in the third through holes 36.
Flows into the polyimide film substrate 30 until it overflows a small amount, and the transistor chip T is fixed thereon. As a result, an appropriate amount of the Ag paste 38 for securing the transistor chip T can be secured, and the length of the third through hole 36 is longer than one side of the transistor chip T.
The paste 38 can be spread on the lower surface of the transistor chip T on the polyimide film substrate 30, and the Ag paste 38 can serve as a die pad of the transistor chip T. Furthermore, air bubbles remaining on the lower surface of the transistor chip T when the transistor chip T is fixed can also be extracted from the third through holes 36 protruding on both sides of the transistor chip T, and a good connection between the third electrode 33 and the transistor chip T can be obtained. Is obtained.

Therefore, in the single-sided electrode structure proposed in the present invention, the third electrode 33 can be terminated inside the transistor chip T, and the area can be made much smaller than in the conventional single-sided electrode structure. Became. As a result, even if the minimum distance between the electrodes that does not short-circuit with solder or the like during the mounting is maintained, the first electrode 31 and the second
The electrode 32 and the third electrode 33 can have a smaller occupation area than the conventional single-sided electrode structure. As a result, the occupied area of the package per element is vertical (1 m).
m) × width (0.8 mm).

Next, the polyimide film substrate 30 used in the present invention will be described with reference to FIG. 3A shows a top view, and FIG. 3B shows a back view.

First, a plurality of mounting portions 40 are formed on the polyimide film substrate 30. For example, 100 mounting units are arranged on a substrate in 10 rows and 10 columns vertically and horizontally.

Electroless plating of copper is performed on the back surface of the polyimide film substrate 30, and then a thickness of 20 mm is formed by electrolytic plating of copper.
A μm copper foil is formed on the entire surface. Subsequently, the third electrode 33
Is etched into a meandering pattern of the same shape in which the first electrode 31 and the second electrode 32 of the mounting portion 40 adjacent to are connected to each other to form a single-sided electrode.

Next, from the surface of the polyimide film substrate 30, each of the through holes 34, 35, 3
6 is formed.

The first through hole 34 and the second through hole 35 are formed as one through hole in common with the adjacent mounting portion 40. By forming the first through-hole 34 and the second through-hole 35 as one through-hole, it is possible to secure a size enough to accommodate a capillary used when performing a bonding wire. This also allows the first through hole 34 and the second through hole 35 to be formed with a minimum size.

As shown in FIG. 2, a transistor chip T is fixed to each mounting portion 40 surrounded by a square of the polyimide film substrate 30 with an Ag paste 38, and connected to each electrode by a bonding wire. After molding with the resin layer 39, the dicing line 4 between the mounting portions 40 is formed.
Dicing along 1 separates into individual mounting parts. At this time, the mounting portion 4 adjacent to the connected third electrode 33
The first electrode 31 and the second electrode 32 of 0 are cut to become the respective electrodes 31, 32, 33 of the respective mounting portions.

[0037]

As described above, according to the present invention, there is an advantage that it is possible to provide a package structure that can be made thinner and lighter by the thickness of one side of the conductive foil than a semiconductor device using a double-sided electrode structure. .

In addition, although the present invention employs a single-sided electrode structure, the semiconductor chip can be fixed directly on the upper surface of the insulating substrate by flowing Ag paste through a through hole longer than one side of the semiconductor chip. The occupied area can be greatly reduced as compared with the single-sided electrode structure.

Further, in the present invention, by forming a through-hole longer than one side of the semiconductor chip and flowing the Ag paste, it is possible to prevent bubbles from remaining on the back surface of the die and insufficient flow.

Further, according to the present invention, the formation of via holes, which is indispensable in the double-sided electrode structure, becomes unnecessary, so that the through-hole process can be entirely eliminated, and a very simple mounting structure can be realized.

Further, in the present invention, the through hole for wire bonding is shared with the adjacent mounting portion,
Despite its small package size, it can be easily wire-bonded to the bottom of the through hole.

[Brief description of the drawings]

FIGS. 1A and 1B are a top view and a back view for explaining a semiconductor device of the present invention; FIGS.

FIG. 2 is a cross-sectional view illustrating a semiconductor device of the present invention.

FIGS. 3A and 3B are a top view and a back view, respectively, for explaining a single-sided electrode substrate used in the semiconductor device of the present invention. FIGS.

FIG. 4 is a cross-sectional view illustrating a conventional semiconductor device.

FIG. 5 is a cross-sectional view illustrating a conventional semiconductor device.

FIG. 6 is a cross-sectional view illustrating a conventional semiconductor device.

FIGS. 7A and 7B are a top view and a back view, respectively, for explaining a conventional semiconductor device.

FIG. 8 is a cross-sectional view illustrating a conventional semiconductor device.

Claims (6)

[Claims] 1. A semiconductor chip fixed to an upper surface of an insulating substrate, a lower electrode of a die provided on a lower surface of the insulating substrate, a through hole provided in the insulating substrate, and a lower surface of the semiconductor chip and the die filled in the through hole. A conductive paste for electrically connecting the electrodes to each other, wherein the width of the through hole is formed to be narrower than one side of the semiconductor chip, and the length of the through hole is formed to be longer than one side of the semiconductor chip. Wherein one end of the through hole extends at least to the outside of the semiconductor chip. 2. The semiconductor device according to claim 1, wherein said through-hole is arranged along a center line of said semiconductor chip, and both ends of said through-hole extend to outside of said semiconductor chip. 3. An extraction lower electrode is provided on the lower surface of the insulating substrate adjacent to the die lower electrode, a through hole is also provided on the extraction lower electrode, and the extraction lower electrode exposed at the bottom of the through hole is provided. 2. The semiconductor device according to claim 1, wherein an electrode of the semiconductor chip is connected with a bonding wire. 4. The semiconductor device according to claim 1, wherein said conductive paste is an Ag paste. 5. The semiconductor device according to claim 1, further comprising an insulating resin including the semiconductor chip and covering an upper surface of the insulating substrate. 6. The semiconductor device according to claim 1, wherein said insulating substrate is formed of polyimide.