Semiconductor device and method of fabricating the same

Abstract

A semiconductor device comprises a semiconductor IC chip provided with bond pads on its first surface, a wiring board provided with a through hole extending between the opposite surfaces thereof, conductive members electrically connecting the bond pads of the semiconductor IC chip to those formed on the wiring board, and a sealing resin coating coating the surface of the semiconductor IC chip and the conductive members, and bonding the side surfaces of the semiconductor IC chip to the side surfaces of the through hole of the wiring board.

Description

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a semiconductor device and a method of fabricating the same. More particularly, the present invention relates to a thin semiconductor device that permits high-density packaging, and a method of fabricating the semiconductor device.

[0004] 2. Description of the Related Art

[0005] A conventional semiconductor device is constructed by fixing a semiconductor IC chip to a wiring board with an adhesive, electrically connecting bond pads of the semiconductor IC chip to bond pads formed on the wiring board with metal wires, and sealing the semiconductor IC chip and the metal wires in a resin for protection.

[0006] When fabricating this conventional semiconductor device, the semiconductor IC chip is fixed to the wiring board with the adhesive, the bond pads of the semiconductor IC chip are electrically connected to the bond pads of the wiring substrate using metal wires, and the semiconductor IC chip and the metal wires are covered with and sealed in the resin.

[0007] The conventional technique, however, has the following problems. The respective thicknesses of the semiconductor IC chip and the layer of the adhesive bonding the semiconductor IC chip to the wiring substrate are included in the thickness of the semiconductor device, which makes it difficult to form the semiconductor device in a small thickness.

[0008] The area of the layer of the adhesive is greater than that of the semiconductor IC chip, and the layer of the adhesive spreads in an unpredictable shape when compressed between the semiconductor IC chip and the wiring board. Therefore, the bond pads of the wiring board to which the bond pads of the semiconductor IC chip are to be connected by the metal wires must be spaced from the periphery of the semiconductor IC chip by, for example, 8 mm or above, which makes high-density packaging difficult.

SUMMARY OF THE INVENTION

[0009] Accordingly, it is an object of the present invention to provide a thin semiconductor device that enables permitting high-density packaging thereof.

[0010] With the foregoing object, the present invention provides a semiconductor device comprising a semiconductor IC chip provided on its first surface with bond pads; a wiring substrate provided with a through hole extending between its first surface and its second surfaces opposed to the first surface; conductive members electrically connecting the bond pads of the semiconductor IC chip to conductive lines formed on the wiring substrate; and a resin molding covering the surface of the semiconductor IC chip and fixing side surface of the semiconductor IC chip to side surface of the through hole.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention, the objects and features of the invention and further objects, features and advantages thereof will be better understood from the following description taken in connection with the accompanying drawings in which:

[0012] FIG. 1 is a sectional view of a semiconductor device in a first embodiment according to the present invention;

[0013] FIGS. 2(a) to 2(e) are typical sectional views of assistance in explaining a method of fabricating the semiconductor device in the first embodiment;

[0014] FIGS. 3(a) to 3(d) are typical sectional views of assistance in explaining another method of fabricating the semiconductor device in the first embodiment;

[0015] FIG. 4 is a typical sectional view of assistance in explaining a method of forming wiring lines by using a conductive paste;

[0016] FIGS. 5(a) to 5(c) are typical sectional views of assistance in explaining a method of forming wiring lines by using a conductive paste;

[0017] FIGS. 6(a) to 6(d) are typical sectional views of assistance in explaining a method of forming wiring lines by using a conductive paste; and

[0018] FIG. 7 is a typical sectional view of a semiconductor device in a second embodiment according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

[0019] Referring to FIG. 1, a semiconductor device in a first embodiment according to the present invention comprises a semiconductor IC chip 1 provided on its front surface with bond pads, a wiring substrate 2 provided with a through hole, metal wires 3, and a sealing resin coating 4. The metal wires 3 are extended to a height 5 that is described below. The sealing resin coating 4 has a height 6 that is described below. The back surface of the semiconductor IC chip 1 is spaced a distance 7 apart from the back surface of the wiring substrate 2.

[0020] Referring to FIG. 1, the semiconductor IC chip 1 is inserted in the through hole of the wiring board 2, and the bond pads of the semiconductor IC chip 1 are electrically connected to the bond pads formed at the edge of the conductive lines of the wiring substrate 2 using the metal wires 3. The sealing resin coating molding 4 coats the semiconductor IC chip 1 and the metal wires 3. Part of the sealing resin coating 4 fills up gaps between the side surfaces of the semiconductor IC chip 1 and the side surface of the through hole of the wiring substrate 2 to bond the semiconductor IC chip 1 to the wiring substrate 2.

[0021] The height 5 of the metal wires 3 is in the maximum range of 150 to 250 μm, and hence the thickness 6 of the sealing resin coating 4 is in the range of 170 to 270 μm. The thickness 6 is 270 μm. The sealing resin coating 4 may possibly flow through the gaps between the side surfaces of the semiconductor IC chip 1 and the side surfaces of the through hole of the wiring substrate 2 onto the back surface of the semiconductor IC chip 1. Therefore, the back surface of the semiconductor IC chip 1 is separated from the back surface of the wiring substrate 2 by a distance 7 of 50 μm or more. If the sealing resin coating 4 that flowed onto the back surface of the semiconductor IC chip 1 is removed later, the back surface of the semiconductor IC chip 1 may be flush with the second surface of the wiring substrate 2, i.e., the distance 7 may be naught.

[0022] Since the semiconductor IC chip 1 is inserted in the through hole of the wiring substrate 2, the thickness 6 of the sealing resin coating 4 is dependent substantially only on the height 5 of the metal wires 3 and is less than that of the sealing resin coating of the corresponding conventional semiconductor device.

[0023] Thus, the semiconductor device of the present invention can be formed having a small thickness.

[0024] Since the semiconductor IC chip 1 is inserted in the through hole of the wiring substrate 2, the length of the metal wires 3 is shorter than that of corresponding conventional semiconductor and hence the total resistance of the metal wires 3 can be decreased.

[0025] Since the semiconductor IC chip 1 is inserted in the through hole of the wiring substrate 2, the semiconductor IC chip 1 can be attached to the wiring substrate 2 with its front surface substantially flush with the front surface of the wiring substrate 2 and hence the faulty coating of the semiconductor IC chip 1 and the metal wires 3 with the sealing resin coating attributable to steps between the semiconductor IC chip 1 and the wiring board 2 will rarely occur. Since no adhesive is used for attaching the semiconductor IC chip 1 to the wiring board 2, the bond pads of the wiring board need not be separated far from the edges of the semiconductor IC chip 1 to avoid being covered with an irregularly spread layer of an adhesive. The distance between the edges of the semiconductor IC chip 1 and the bond pads of the wiring board 2 may be about 0.3 mm. Accordingly, the sealing resin coating 4 can be formed in a small area, which enables high-density packaging.

[0026] Since the semiconductor IC chip 1 is attached to the wiring substrate 2 without using any adhesive, there is no occurrence of separation of the sealing resin coating 4 and the wiring substrate 2 from each other by the shrinkage of an adhesive, when used, bonding the semiconductor IC chip 1 to the wiring board 2 caused by a heat shock exerted on the adhesive or the disconnection of the metal wires 3 from the bond pads of the wiring substrate 2.

[0027] A tape provided with conductive wires, wires of a conductive paste may be used instead of the metal wires 3 to connect the bond pads of the semiconductor IC chip 1 to the bond pads of the wiring substrate 2. Generally, such a tape has a thickness in the range of 60 to 200 μm and hence the thickness 6 of the sealing resin coating 4 may be in the range of about 80 to 200 μm, which enables the fabrication of a semiconductor device having a further reduced thickness. Wires of a conductive paste are formed in a thickness in the range of 60 to 200 μm and hence the thickness 6 of the sealing resin coating 4 may be in the range of abut 50 to 220 μm, which also enables the fabrication of a semiconductor device having a further reduced thickness. Wires of a conductive paste do not come off the wiring substrate 2 easily because of their large area in contact with the wiring substrate 2.

[0028] A method of fabricating the semiconductor device in the first embodiment will be described hereinafter with reference to FIGS. 2(a) to 2(e), in which 8 is an adhesive tape and 9 is a stage provided with a projection, and parts like or corresponding to those shown in FIG. 1 are designated by the same reference characters.

[0029] As shown in FIG. 2(a), adhesive tape 8 provided with an adhesive layer is attached to the second surface of the wiring board 2, and the semiconductor IC chip 1 is inserted in the through hole of the wiring board 2 so as to be attached to the adhesive tape 8.

[0030] As shown in FIG. 2(b), the wiring substrate 2 is placed on stage 9 provided with a projection so that the projection of the stage 9 is fitted in the through hole of the wiring substrate 2 to push up the semiconductor IC chip 1 relative to the wiring board 2. Since the semiconductor IC chip 1 and the stage 9 have dimensional errors, the front surface of the semiconductor IC chip 1 extends at a height from the front surface of the wiring substrate 2 in the range of 150 μm.

[0031] As shown in FIG. 2(c), the bond pads of the semiconductor IC chip 1 are connected to the bond pads formed at the edge of the wiring substrate 2 by the metal wires 3, respectively.

[0032] As shown in FIG. 2(d), the semiconductor IC chip 1 and the metal wires 3 are coated with the sealing resin coating 4. Part of the sealing resin coating 4 fills up gaps between the side surface of the semiconductor IC chip 1 and the side surface of the through hole of the wiring substrate 2.

[0033] Finally, as shown in FIG. 2(e), the semiconductor device formed by thus assembling the semiconductor IC chip 1, the wiring board 2, the metal wires 3 and the sealing resin coating 4 is separated from the adhesive tape 8 and the stage 9.

[0034] Another method of fabricating the semiconductor device in the first embodiment is illustrated by FIGS. 3(a) to 3(d), in which 10 indicates a stage having a projection provided with an air passage.

[0035] As shown in FIG. 3(a), the projection of the stage 10 is inserted in the through hole of the wiring substrate 2, and the semiconductor IC chip 1 is inserted in the through hole of the wiring board 2 and is seated on the projection of the stage 10. Since the semiconductor IC chip I and the stage 10 have dimensional errors, the front surface of the semiconductor IC chip 1 extends at a height from the front surface of the wiring board 2 in the range of 150 μm.

[0036] As shown in FIG. 3(b), the bond pads of the semiconductor IC chip 1 are connected to the bond pads of the wiring substrate 2 by the metal wires 3, respectively, by a wire bonding process. During the wire bonding process, suction is exerted on the semiconductor IC chip 1 through the air passage to hold the semiconductor IC chip 1 fixedly in place on the stage 10.

[0037] As shown in FIG. 3(c), the semiconductor IC chip 1 and the metal wires 3 are coated with the sealing resin coating 4. Part of the sealing resin coating 4 fills up gaps between the side surface of the semiconductor IC chip 1 and the side surface of the through hole of the wiring substrate 2.

[0038] Finally, as shown in FIG. 3(d), the semiconductor device formed by thus assembling the semiconductor IC chip 1, the wiring substrate 2, the metal wires 3 and the sealing resin coating 4 is separated from the stage 10.

[0039] The foregoing methods of fabricating the semiconductor device in the first embodiment connect the bond pads of the semiconductor IC chip 1 to those of the wiring substrate 2 by the metal wires 3. Those methods may use tape provided with conductive wires or wires of a conductive paste instead of the metal wires 3.

[0040] A method of forming wiring lines of a conductive paste will be described hereinafter with reference to FIG. 4, in which 11 indicates a wire of a conductive paste and 12 indicates a nozzle, and parts like or corresponding to those shown in FIGS. 3(a) to 3(d) are designated by the same reference characters. As shown in FIG. 4, the conductive paste is applied to the first surfaces of the semiconductor IC chip 1 and the wiring board 2 by the nozzle 12 so as to form wiring lines 11 interconnecting the bond pads of the semiconductor IC chip 1 and the wiring board 2.

[0041] FIGS. 5(a) to 5(c) illustrate another method of forming wires of a conductive paste, in which 13 indicates a mask having a pattern of open areas corresponding to a pattern of wires and indicates 14 a squeegee, and parts like or corresponding to those shown in FIG. 4 are designated by the same reference characters.

[0042] As shown in FIG. 5(a), the mask 13 is disposed on the wiring board 2 so that the open areas of the mask 13 correspond to regions in which wiring lines are formed on the semiconductor IC chip 1 and the wiring board 2, respectively.

[0043] Subsequently, as shown in FIG. 5(b), a mass of a conductive paste is put on the mask 13.

[0044] Finally, as shown in FIG. 5(c), the squeegee 14 is moved along the surface of the mask 13 in the direction of the arrow to spread the conductive paste into the open areas of the mask 13 to form the wiring lines 11. The wiring lines 11 can be formed in a substantially uniform thickness depending on the thickness of the mask 13. The wiring lines 11 can be formed in a desired thickness by selectively determining the thickness of the mask 13.

[0045] FIGS. 6(a) to 6(d) illustrate a third method of forming the wires 11 of a conductive paste, in which 15 indicates a transfer roller and 16 indicates a letterpress printing plate, and parts like or corresponding to those shown in FIG. 4 are designated by the same reference characters.

[0046] As shown in FIG. 6(a), the transfer roller 15 is rotated in the direction of the arrow, and the letter press printing plate 16 having surface areas coated with a pattern of a conductive paste corresponding to a pattern of wires 11 is moved in the direction of the arrow at a speed equal to the circumferential speed of the transfer roller 15 to transfer a pattern of the conductive paste corresponding to the pattern of wires 11 to be formed on the semiconductor IC chip 1 and the wiring substrate 2 from the letterpress printing plate 16 to the transfer roller 15.

[0047] As shown in FIG. 6(b), a stage 10 supporting the wiring substrate 2 and the semiconductor IC chip 1 inserted in the through hole of the wiring substrate 2 presses the wiring substrate 2 against the circumference of the transfer roller 15 and is moved in the direction of the arrow opposite the moving direction of the letterpress printing plate 16 at a speed equal to the circumferential speed of the transfer roller 15.

[0048] Consequently, the pattern of the conductive paste is transferred from the transfer roller 15 to the semiconductor IC chip 1 and the wiring substrate 2 as shown in FIG. 6(c) and the wires 11 of the conductive paste are formed on the front surfaces of the semiconductor IC chip 1 and the wiring substrate 2 as shown in FIG. 6(d).

Second Embodiment

[0049] A semiconductor device in a second embodiment according to the present invention is shown in FIG. 7, in which parts like or corresponding to those of the first embodiment are designated by the same reference characters.

[0050] The semiconductor device in the second embodiment has a wiring substrate 2 provided with a through hole extending between the opposite surfaces thereof, and two semiconductor IC chips 1 each provided with bond pads on one surface thereof and inserted in the through hole of the wiring substrate 2 in a back-to-back arrangement with the surfaces not provided with the bond pads facing each other. The bond pads of the semiconductor IC chips 1 are electrically connected to the bond pads formed at the edge of the conductive lines of the wiring substrate 2 using metal wires 3. Sealing resin coatings 4 seal the semiconductor IC chips 1 and the metal wires 3 therein and bond together the semiconductor IC chips 1 and the wiring board 2. The sealing resin coatings 4 fill up gaps between the side surface of the semiconductor IC chips 1 and the side surfaces of the through hole of the wiring substrate 2.

[0051] The metal wires 3 extend to a height in the range of 150 to 250 μm, and each of the sealing resin coatings 4 has a height 6 in the range of about 170 to 270 μm. The maximum thickness 6 is 270 μm.

[0052] The bond pads of the semiconductor IC chips 1, similar to those of the semiconductor device in the first embodiment, may be connected electrically to the bond pads of the wiring substrate 2 by a tape provided with conductive wires or by wires of a conductive paste. When wires of a conductive paste are employed, the same may be formed by the method of forming the wires of the conductive paste previously described in connection with the first embodiment.

[0053] The semiconductor device in the second embodiment, similar to that in the first embodiment, is fabricated by inserting one of the semiconductor IC chips 1 in the through hole of the wiring substrate 2, electrically connecting the bond pads of the semiconductor IC chip 1 to bond pads formed on one of the opposite surfaces of the wiring substrate 2 using the metal wires 3, coating the semiconductor IC chip 1 and the metal wires 3 with the sealing resin coating 4, inverting the wiring substrate 2 upside down, inserting the other semiconductor IC chip 1 in the through hole of the wiring substrate 2, electrically connecting the bond pads of the semiconductor IC chip 1 to bond pads formed on the other surface of the wiring substrate by the metal wires 3, and coating the semiconductor IC chip 1 and the metal wires 3 with the sealing resin coating 4.

[0054] The semiconductor device in the second embodiment, similar to that in the first embodiment, can be formed in a small thickness and permit high-density packaging. Further, since two semiconductor IC chips are inserted in the through hole of the wiring substrate, the semiconductor device in the second embodiment has multi-function.

[0055] The semiconductor device in the present invention can be formed with a small thickness because the semiconductor IC chips are inserted in the through hole of the wiring board. Since no adhesive is used for attaching the semiconductor IC chips to the wiring substrate, the bond pads of the wiring substrate need not be separated far from the edges of the semiconductor IC chips to avoid being covered with an irregularly spread layer of an adhesive. The bond pads of the wiring substrate may be formed at positions close to the edges of the semiconductor IC chips. Accordingly, the semiconductor device can be formed in a small area, which enables high-density packaging.

[0056] The foregoing embodiments of the present invention are illustrative and not restrictive. It is obvious to those skilled in the art that various changes and modifications are possible in the foregoing embodiments without departing from the scope and spirit of the invention. The scope of the invention, therefore, is to be determined solely by the following claims.

Claims

1. a semiconductor device comprising: a semiconductor IC chip provided with bond pads on a first surface thereof; a wiring board provided with a through hole extending between first and second surfaces thereof; conductive members connecting the bond pads of the semiconductor IC chip to bond pads formed on the first surface of the wiring board; and a sealing resin coating the first surface of the semiconductor IC chip and bonding side surfaces of the semiconductor IC chip to side surfaces of the through hole.

2. The semiconductor device according to claim 1, wherein the first surface of the semiconductor IC chip is substantially flush with the first surface of the wiring board.

3. The semiconductor device according to claim 1, wherein the conductive members are wiring lines formed on a surface of a tape.

4. The semiconductor device according to claim 1, wherein the conductive members are formed of a conductive paste.

5. A semiconductor device comprising: a semiconductor IC chip provided with bond pads on a first surface thereof; a wiring board provided with a through hole extending between first and second surfaces thereof; conductive members electrically connecting the bond pads of the semiconductor IC chip to bond pads formed on the first surface of the wiring board; and a sealing resin coating coating the first surface of the semiconductor IC chip and bonding side surfaces of the semiconductor IC chip to side surfaces of the through hole; wherein semiconductor IC chip is disposed in the through hole of the wiring board with its second surface spaced a predetermined distance apart from the second surface of the wiring board.

6. The semiconductor device according to claim 5, wherein the first surface of the semiconductor IC chip is substantially flush with the first surface of the wiring board.

7. The semiconductor device according to claim 5, wherein the predetermined distance between the respective second surfaces of the semiconductor IC chip and the wiring board is 50 μm or above.

8. The semiconductor device according to claim 5, wherein the conductive members are wiring lines formed on a surface of a tape.

9. The semiconductor device according to claim 5, wherein the conductive members are formed of a conductive paste.

10. A semiconductor device comprising: a first semiconductor IC chip provided with bond pads on a first surface thereof; a wiring board provided with a through hole extending between first and second surfaces thereof; first conductive members electrically connecting the bond pads of the first semiconductor IC chip to bond pads formed on the first surface of the wiring board; a second semiconductor IC chip formed in a shape substantially the same as that of the first semiconductor IC chip and provided with bond pads on a first surface thereof; second conductive members electrically connecting the bond pads of the second semiconductor IC chip to bond pads formed on the second surface of the wiring board; and sealing resin coatings coating the respective first surfaces of the first and the second semiconductor IC chip and bonding side surfaces of the first and the second semiconductor IC chip to side surfaces of the through hole.

11. The semiconductor device according to claim 10, wherein at least the first surface of the first semiconductor IC chip is substantially flush with the first surface of the wiring board or the first surface of the second semiconductor IC chip is substantially flush with the second surface of the wiring board.

12. The semiconductor device according to claim 10, wherein the first and the second conductive members are wiring lines formed on tapes.

13. The semiconductor device according to claim 10, wherein the first and the second conductive members are formed of a conductive paste.

14. A semiconductor device fabricating method comprising the steps of: attaching an adhesive tape to a first surface of a wiring board provided with a through hole extending between the first surface and a second surface; inserting a semiconductor IC chip provided with bond pads on its first surface in the through hole so that the semiconductor IC chip is bonded to a part of the adhesive tape exposed in the through hole; seating the wiring board on a stage having a projection so that the semiconductor IC chip is pushed up relative to the wiring board by a predetermined distance from the second surface of the wiring board by the projection of the stage; electrically connecting the bond pads of the semiconductor IC chip to bond pads formed on a first surface of the wiring board by conductive members; coating the first surface of the semiconductor IC chip and the conductive members with a sealing resin coating and bonding the surfaces of the semiconductor IC chip to side surfaces of the through hole with the sealing resin coating; and removing the adhesive tape from the second surface of the wiring board.

15. The semiconductor device fabricating method according to claim 14, wherein the step of electrically connecting the bond pads of the semiconductor IC chip to those of the wiring board by the conductive forms the conductive members by extruding a conductive paste through a nozzle onto the semiconductor IC chip and the wiring board.

16. The semiconductor device fabricating method according to claim 14, wherein the step of electrically connecting the bond pads of the semiconductor IC chip to those of the wiring board by the conductive members comprises: placing a mask having a pattern of open areas corresponding to a desired wiring pattern at a predetermined position on the first surface of the wiring board; and spreading a conductive paste into the open areas of the mask.

17. The semiconductor device fabricating method according to claim 14, wherein the step of electrically connecting the bond pads of the semiconductor IC chip to those of the wiring board by the conductive members forms the conductive members by transferring a pattern of a conductive paste corresponding to a pattern of the conductive members to the semiconduct or IC chip and the wiring board.

18. A semiconductor device fabricating method comprising the steps of: preparing a stage having a projection provided with an air passage opening into a major surface thereof and disposing a wiring board provided with a through hole extending between opposite surfaces thereof with the projection of the stage fitted in the through hole; inserting a semiconductor IC chip provided with bond pads on its first surface in the through hole of the wiring board so as to be seated on the major surface of the projection of the stage; exerting suction through the air passage to the semiconductor IC chip to hold fast the semiconductor IC chip on the major surface of the projection of the stage; electrically connecting the bond pads of the semiconductor IC chip to bond pads formed on the first surface of the wiring board by conductive members; and coating the semiconductor IC chip and the conductive member with a sealing resin coating and bonding side surfaces of the semiconductor IC chip to side surfaces of the through hole with the sealing resin coating.

19. The semiconductor device fabricating method according to claim 18, wherein the step of electrically connecting the bond pads of the semiconductor IC chip to those of the wiring board by the conductive members forms the conductive members by extruding a conductive paste through a nozzle onto the semiconductor IC chip and the wiring board.

20. The semiconductor device fabricating method according to claim 18, wherein the step of electrically connecting the bond pads of the semiconductor IC chip to those of the wiring board by the conductive members comprises: placing a mask having a pattern of open areas corresponding to a desired wiring pattern at a predetermined position on the first surface of the wiring board; and spreading a conductive paste into the open areas of the mask.

21. The semiconductor device fabricating method according to claim 18, wherein the step of connecting the bond pads of the semiconductor IC chip to those of the wiring board by the conductive members forms the conductive members by transferring a pattern of a conductive paste corresponding to a pattern of the conductive members to the semiconductor IC chip and the wiring board.