Interposer for semiconductor device

A substrate 1 of a insulating resin material is provided with a semiconductor chip 2 in the center of the substrate 1 and a lot of fine studs are filled in the substrate 1 around the chip 2. A bonding pad 13 and a land 14 are formed on both end planes of each stud 12 by silver plating. The length of the stud 12 is determined so that the plane of the land 14 and the back side plane of the substrate are approximately co-planar, but it may be longer. The substrate 1 including the studs 12 having the bonding pad 12 and the land 14 is defined as an interposer 15.

BACKGROUND OP THE INVENTION 
This invention relates to a semiconductor device, an interposer for a 
semiconductor device and a method for manufacturing the same, and more 
particularly to, a semiconductor device including a semiconductor chip, an 
interposer to be used as a substrate or a lead frame for mounting a 
semiconductor chip and a method for manufacturing the same. 
A conventional semiconductor device having a ball grid array (BGA) 
packaging comprises a substrate, a semiconductor chip (IC, LSI chip) 
mounted on the surface of the substrate, first wiring patterns formed 
around the chip, each of which is connected to each pad on the chip by a 
bonding wire, second wiring patterns formed on the back side of the 
substrate, throughholes having a plating on the inner surfaces thereof for 
connecting the first wiring pattern to the corresponding second wiring 
pattern, and solder balls for connecting the second wiring pattern to an 
input-output wiring pattern formed on a circuit board by a reflow solder. 
All parts mounted or formed on the surface of the substrate are covered by 
a molding resin. 
Similar conventional devices and methods for manufacturing the same are 
known by many publications. For example, Japanese Published Patent 
Application No. 3-94459 discloses a semiconductor chip module comprising a 
die-bonding pad and a bonding pad having a non-etching metal layer, such 
as a gold plating, formed on a metal plate base, and a method for 
manufacturing the same. Japanese Published Utility-model Application No. 
63-3160 discloses an integrated circuit device comprising a lead frame 
protruding from the back side of a resin package, and a heat-resisting 
insulating tape disposed on the the same side thereof. Japanese Published 
Patent Application No. 5-63109discloses a molded IC package comprising a 
contact hole formed inside a resin for conducting a inner lead to the 
surface or back side of a package, and a conductive filler filled into the 
contact hole so as to be used as an input-output contact. Japanese 
Published Patent Application No. 5-283460 discloses a semiconductor device 
comprising a semiconductor chip mounted on a insulating base-film on which 
a lead pattern is formed, and a bump connected to the lead pattern and 
exposed from the base-film. Japanese Published Patent Application No. 
6-112354 discloses a thin over-molded semiconductor device comprising a 
semiconductor die mounted on a substrate having a conductive layer, and a 
solder ball connected to the conductive layer and exposed from the 
substrate, and a method for manufacturing the same. Japanese Published 
Patent Application No. 6-216276 discloses a semiconductor device 
comprising a wiring pattern formed on a substrate so that a plane thereof 
is higher than that of a substrate on which a semiconductor chip is 
mounted, and a throughhole, wherein the inner and outer ends of the wiring 
pattern is connected to the semiconductor chip and the throughhole, 
respectively, and a solder bump is connected to an exposed portion of the 
throughhole. Japanese Published Patent Application No. 5-144995 discloses 
a semiconductor package comprising a package substrate having a 
throughhole, and a metal ball interposed between the lower end of the 
throughhole and an input-output pattern on a circuit board. Japanese 
Published Patent Application No. 5-211202 discloses a composite flip-chip 
semiconductor device comprising a interposer having a plurality of 
conducting paths provided on both side of a substrate and a conductive 
trace for connecting the paths formed on the surface of the substrate, and 
a metal ball for connecting a flip-chip semiconductor device, and a method 
for manufacturing the same. Japanese Published Patent Application No. 
3-269962 discloses a connecting member comprising a pair of resin holder 
for holding a conductive member in a manner that the conducting member 
protrudes from the resin holder, wherein the surface of the conductive 
member is coated by a solder. 
In the conventional semiconductor devices, however, there are disadvantages 
as described below; 
(a) the device disclosed in Japanese Published Patent Application No. 
3-94459 comprises a large number of parts, hence resulting in increased 
cost for materials and increased assembly costs. 
(b) the effective inductance is increased because the length of a wiring 
pattern is long. Therefore, crosstalk noise increases correspondingly and 
high-speed transmission characteristics become worse in signal 
transmission. 
(c) fatigue failure due to thermal stress in heat cycle is likely to occur 
because there are a lot of wiring contacts in the device. 
(d) additionally, reliability decreases because the throughholes and solder 
balls themselves are subject to fatique failure. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the invention to provide a semiconductor 
device, an interposer for a semiconductor device and a method for 
manufacturing the same by which a structure thereof is simple and a size 
thereof is small. 
It is a further object of the invention to provide a semiconductor device, 
an interposer for a semiconductor device and a method for manufacturing 
the same by which effective inductance and noise in signal transmission 
are reduced. 
It is a still further object of the invention to provide a semiconductor 
device, an interposer for a semiconductor device and a method for 
manufacturing the same by which the cost is low but reliability and 
productivity are high. 
According to the first feature of the invention, a semiconductor device, 
comprises: 
a substrate; 
a semiconductor chip mounted on the substrate; 
a plurality of conductive studs disposed around the semiconductor chip as 
input-output terminals; and 
a plurality of bonding wires for connecting each bonding pad on the 
semiconductor chip to the conductive studs, respectively; 
wherein both side planes of the conductive stud are exposed from the 
surface and back side plane of the substrate, respectively, whereby the 
side planes function as a bonding pad and a land. 
According to the second feature of the invention, an interposer for a 
semiconductor device comprises: 
a substrate having a die pad where a semiconductor chip is to be mounted; 
and 
a plurality of conductive studs disposed around the die pad as input-output 
terminals; 
wherein both side planes of the conductive stud are exposed from the 
surface and back side plane of the substrate, respectively, whereby the 
side planes function as a bonding pad and a land. 
According to the third feature of the invention, a method for manufacturing 
an interposer for a semiconductor device, comprises the steps of: 
preparing a substrate in which a plurality of holes are provided; 
inserting conductive studs into each said hole.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Before explaining in the first preferred embodiment, the aforementioned 
conventional semiconductor device will be explained in FIGS. 1, 2 and 3. 
FIG. 1 shows the conventional semiconductor device having a ball grid array 
(BGA) packaging. The conventional semiconductor device comprises a 
substrate 1, a semiconductor chip 2 mounted on the surface of the 
substrate 1, first wiring patterns 3 formed around the chip 2, each of 
which is connected to each pad (not shown) on the chip 2 by a bonding wire 
7, second wiring patterns 6 formed on back side of the substrate 1, 
throughholes 4 having a plating 5 on the inner surfaces thereof, land 3a, 
and solder balls 10. As shown in FIG. 2, wherein a molding resin 11 and 
some of first wiring patterns 3 are omitted, the first wiring pattern 3 is 
connected to the corresponding second wiring pattern 6 through the land 3a 
and the plating 5. Finally, all parts mounted or formed on the front side 
of the substrate 1 are covered by the molding resin 11, then the 
semiconductor device is complete. 
FIG. 3 shows a conventional connecting structure of the semiconductor 
device to a circuit board, wherein the molding resin 11 is omitted. As 
shown in FIG. 3, this conventional semiconductor device is mounted on a 
circuit board 8 by connecting the second wiring pattern 6 on the back side 
of the substrate 1 to an input-output wiring pattern 9 formed on the 
circuit board 8 electrically and mechanically by reflow solders 10a and 
l0b melted by a reflow heater, for example. 
In the conventional semiconductor device, as described before however, 
there are disadvantages in that; 
(a) the cost of materials and assembly become high. 
(b) the effective inductance becomes high. Therefore, crosstalk noise 
increases and high-speed transmission characteristics become worse during 
signal transmission. 
(c) fatigue failure due to thermal stress is likely to occur. 
(d) reliability becomes worse. 
Next, a semiconductor device and an interposer for a semiconductor device 
in the first preferred embodiment will be explained with reference to 
FIGS. 4 and 5, wherein like parts are indicated by like reference numerals 
as used in FIGS. 1 and 2. 
In the first preferred embodiment, a substrate 1, which is fabricated from 
a insulating resin material, is provided with an area in the center 
thereof where a semiconductor chip 2 is mounted, and a plurality of fine 
studs filled in the substrate 1 in a certain arrangement, by which the 
semiconductor chip 2 are surrounded. The number of the studs 12 is equal 
to that of the electrodes of the semiconductor chip 2. A bonding pad 13 
for wire-bonding, and a land 14 which is used as a connecting terminal by 
soldering, are formed on the two end planes of each stud 12, respectively. 
Preferably, the bonding pad 13 is formed by silver plating. In the 
embodiment, the length of the stud 12 is determined so that the plane of 
the land 14 and the back side plane of the substrate are approximately 
co-planar. However, it may be longer than the thickness of the substrate 
1, i.e., the lower end plane of the stud 12 may protrude from the back 
side of the substrate 1, whereby a connection of the land 14 to an 
input-output wiring patter on a circuit board becomes easier. In the 
invention, the substrate 1 in which the studs 12 having the bonding pad 12 
and the land 14 are filled is defined as an interposer 15. 
According to the semiconductor device in the first preferred embodiment, 
the semiconductor 2, which is mounted on the interposer 15, is wire-bonded 
by a bonding wire 7 between the bonding pad 13 on the stud 12 and a 
bonding pad (not shown) on the semiconductor chip 2. Then the surface of 
the interposer 15, including the semiconductor chip 2, is molded by a 
molding resin 11, then the semiconductor device 20 is complete. 
FIG. 6 shows the semiconductor device mounted to the circuit board in the 
first preferred embodiment, wherein the molding resin 11 is omitted. In 
comparison with the conventional connecting structure shown in FIG. 3, 
eliminates the need for two wiring patterns 3 and 6, and three connecting 
points in the vicinity of each throughhole 4 which have been required in 
the conventional structure. 
According to the invention, a fine stud 12 functions as both a conductive 
plating in a throughhole and a bonding pad. Additionally, wiring patterns 
on both sides of a substrate are eliminated and the shortest length of 
connection is obtained. Therefore, the effective inductance, and noise 
during signal transmission are both reduced, and high speed operation in 
high clock frequency is possible. Furthermore, the packaging size is 
reduced, the number of parts is reduced, and the number of connecting 
terminals is increased. Therefore, a low cost, small, highly productive 
and highly reliable semiconductor device and interposer are obtained. In 
general, the stud 12 is made of copper and is heat-conductive, thereby 
improving its heat radiation efficiency. It is preferable to plate at 
least one end plane (wire-bonding side) of a stud 12 with a gold or silver 
plating, whereby better bonding characteristics are obtained and 
reliability becomes high. 
In the conventional structure, wiring patterns are necessarily provided for 
extracting bonding pads very close to a semiconductor chip. Current 
wire-bonding techniques has been improved and wire-bonding as long as 
about 15 mm is possible. Therefore there is no problem with the invention, 
by omitting wiring patterns which have a difficulty in fine fabrication. 
FIG. 7 shows a method for manufacturing a preform for an interposer in the 
first preferred embodiment. A plurality of wires 21, such as oxygen-free 
copper (OFC) wires of 0.3 mm diameter, are supplied to an extruder 22. 
Pellets of an insulating material 25, such as thermoplastic fluorine 
resin, are also supplied from a hopper 24 to the extruder 22. The 
insulating material 25 is heated, melted at a die 23 and extruded among 
the wires 21, then, a continuous length of preform 26 for an interposer is 
obtained. The die 23 determines the disposition of each wire 21 and the 
outer shape of the preform 26, so it is exchangeable in every product or 
specification, finally, the preform 26 is cut into slices as a basic 
structure for an interposer 17, which is as thick as about 1 mm. 
FIG. 8 shows a semiconductor device according to a second preferred 
embodiment, wherein like parts are indicated by like reference numerals as 
used in FIGS. 1 and 4. In the embodiment, a semiconductor chip 2 is 
attached on a die pad 16, which is fabricated in the center of a 
interposer 15. Studs 12 that are longer than the thickness of a substrate 
such that, and both end planes thereof protrude beyond the substrate are 
provided with a bonding pad 13 and a land 14, respectively. This 
interposer 15 having the die pad 16 and the studs 12 is made from a metal 
plate according to the method described below. 
As shown in FIG. 9, a metal plate 100, such as Fe-42%-Ni alloy, copper and 
copper alloy plate, is prepared (STEP A). Then, a number of plating pads 
of gold or silver, including bonding pads 101a, a die pad 101b, lands 102a 
and a bottom pad 102b are plated on both sides of the metal plate 100 
(STEP B). Next, the surface of the metal plate 100 is etched 103 by 
photo-chemical etching using an etchant, such as ferric chloride aqueous 
solution. In this case, the bonding pads 101a and the die pad 101b 
function as masks against the etchant (STEP C). After that, an epoxy resin 
104 is injected into the etched portion of the metal plate 100 so that the 
surfaces of the bonding pads 101a and the die pad 101b are still exposing 
(STEP D). Finally, the back side of the metal plate 100 is etched in the 
same manner, as deeply as the back side of the epoxy resin 104 is exposed 
(STEP E). 
FIG. 10 shows an example of a size and arrangement of parts in an 
interposer according to the invention. The interposer 15 of 
C1.times.C2area and includes a die pad 16 of B1.times.B2 area, a plurality 
of bonding pads having a diameter of d. Each bonding pad 13 is formed on 
the top plane of a stud 12 (not shown) and arranged all around the die pad 
16 in a predetermined pitch, which is P1 in width direction and P2 in 
depth direction. Two types of examples of semiconductor device are 
manufactured by using such an interposer 15. The value of each size, 
diameter, pitch (mm) are indicated in TABLE 1. 
TABLE 1 
______________________________________ 
ITEM SIGN EXAMPLE 1 EXAMPLE 2 
______________________________________ 
DIE PAD SIZE B1 5.5 10.5 
B2 5.5 10.5 
KAGE SIZE C1 10.0 20.0 
C2 10.0 20.0 
STUD PITCH P1 0.5 0.5 
P2 0.5 0.5 
BONDING PAD DIAMETER 
d 0.3 0.3 
NUMBER OF PIN n 9B 450 
______________________________________ 
EXAMPLE (1) 
The interposer is fabricated by the method showing in FIG. 7, i.e. an 
extruded preform is cut into slices, cutting planes thereof are ground and 
polished, then nickel plating is provided on one end plane of a stud 12 by 
electroless plating (mean thickness of 1.0 .mu.m, for example). Nickel 
plating is also provided on the other end plane thereof (mean thickness of 
1.0 .mu.m, for example), which is used as a land 16 (not shown). For 
obtaining a semiconductor device, a semiconductor chip 2 (5.0 mm square) 
is attached by silver paste on the die pad 16 (5.5 mm square), then 
bonding pads thereon are connected to the bonding pad 16 on the stud 12 by 
bonding wire 7 (25 .mu.m diameter gold wire, for example). The surface of 
the interposer 15 is molded by a molding resin 11. In this case, a potting 
resin of liquid epoxy is are molded by using a metal mask (1.0 mm thick) 
and printing technique. 
As a result, the mounting area of the 98-pin semiconductor device package 
is quarter as large as that of the conventional one shown in FIG. 1. This 
is because the latter uses an glass epoxy resin substrate, an 
electro-migration through glass fibers in a high temperature, high humid 
environment is critical, so that the pitch of the throughholes is limited 
up to approximately 1.0 mm. 
EXAMPLE (2) 
The size of the die pad and the semiconductor device package are determined 
as shown in TABLE 1. The mounting area of the 450- pin semiconductor 
device package is quarter as large as that of the conventional one. 
FIG. 11 shows a stud 27 used in a third preferred embodiment. In the 
embodiment, an OFC wire of 0.3 mm diameter having a silver plating layer 
of 3.about.5 .mu.m thickness thereon is machined by a header machine (not 
shown), and a machine screw-shaped or a nail-shaped stud 27 is obtained. 
The stud 27 is provided with a swelled head 27b(diameter d , thickness t) 
at one end of a cylindrical body 27a(diameter i, height h). In this case, 
the silver plating has such a good extensibility that it still remains on 
the swelled head 27b after the machining. Therefore, it may function as a 
bonding pad. These studs 27 are inserted into each hole formed around a 
die pad 16 of an interposer 15 having a thickness k, as shown in FIG. 13. 
Such interposer may be manufactured by injection-molding of an epoxy resin 
and machining by a numerical control (NC) lathe. Two types of examples of 
semiconductor device are manufactured by using such interposer 15, the 
value of each size, diameter, pitch (mm) are indicated in TABLE 2. 
TABLE 2 
______________________________________ 
ITEM SIGN EXAMPLE 3 EXAMPLE 4 
______________________________________ 
DIE PAD SIZE B1 5.5 10.5 
B2 5.5 10.5 
KAGE SIZE C1 10.0 20.0 
C2 10.0 20.0 
STUD PITCH P1 0.5 0.5 
P2 0.5 0.5 
STUD SIZE d 0.3 0.3 
t 0.15 0.15 
h 1.5 1.5 
i 0.2 0.2 
NUMBER OF PIN 
n 98 450 
THICKNESS k 1.0 1.0 
______________________________________ 
EXAMPLE (3) 
An interposer 17 having a thickness k of 1 mm epoxy resin, in which 98 
holes are provided, is prepared, and studs 27 are inserted into the hole 
28. Then, a semiconductor device is obtained in the same manner as 
explained in EXAMPLE 1. As a result, the mounting area of the 98-pin 
semiconductor device package is quarter as large as that of the 
conventional one. 
EXAMPLE (4) 
The size of the die pad and the semiconductor device package are determined 
as shown in TABLE 2. the mounting area of the 450- pin semiconductor 
device package is quarter as large as that of the conventional one. 
In the third embodiment, A solder ball, such as 63% Sn-Pb solder may be 
used to connect a land to an input-output wiring pattern easily and 
securely. In this case, printing reflow technique of solder paste may be 
used. 
In the embodiment, not only the same advantages are obtained as in the 
first and second embodiments, but also heat radiation efficiency is much 
improved because machine screw or nail-shaped studs are molded in an 
interposer, In addition to that, fine studs are tightly united by a resin 
substrate and are prevented from slipping off or coming out of the 
substrate. A stud having a same diameter in longitudinal direction may 
also be used, however, the difference of the position is likely to occur. 
If the stud has a swelled head, it is surely aligned in a predetermined 
position, and a wire-bonding is easily operated. 
In the embodiment, other method for obtaining an interposer having a lot of 
studs may be used. For example, studs are positioned in an alignment jig, 
melted epoxy resin is poured into the jig with both ends of each stud 
exposed, then an interposer is obtained without insertion of studs. 
Therefore, machining or molding of a substrate is not necessary and 
productivity is improved. 
Although the invention has been described with respect to specific 
embodiment for complete and clear disclosure, the appended claims are not 
to be thus limited but are to be construed as embodying all modification 
and alternative constructions that may be occur to one skilled in the art 
which fairly fall within the basic teaching here is set forth.