Multi-chip semiconductor chip module

Details Multi-chip semiconductor chip module Multi-chip semiconductor chip module

1998-09-01

2001-09-11

Whitehead, Jr., Carl (Department: 2822)

Semiconductor device manufacturing: process

Coating with electrically or thermally conductive material

To form ohmic contact to semiconductive material

C438S107000, C438S462000, C438S615000

Reexamination Certificate

active

06287949

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to semiconductor devices and more particularly to a multi-chip module including a plurality of semiconductor chips.
2. Description of the Related Art
In relation to recent trend of reducing the size of various electronic apparatuses and devices while simultaneously maintaining, or even increasing, device performance, there is a stringent demand for cutting the time needed for developing new devices and a timely supply of newly developed devices to the market.
Conventionally, semiconductor devices designed for high density mounting have used the so-called QFP (quad flat package) structure that enables an increase in the number of lead pins and decrease of lead pitch.
FIG. 1
shows an example a conventional QFP device
11
mounted upon a printed circuit board
14
.
Referring to
FIG. 1
, the QFP device
11
includes a resin package body
12
in which a semiconductor chip (not illustrated) is accommodated, wherein the QFP device
11
carries a number of lead pins
13
projecting laterally from the circumferential walls or side edges of the package body
12
. The lead pins
13
are bent in the downward direction outside the package body to form a well-known gull wing structure.
The printed circuit board
14
, on the other hand, is formed of a material such as glass epoxy, and carries thereon a conductor pattern
15
in correspondence to the lead wires
13
of the QFP device
11
or other components, wherein the device
11
is mounted upon the substrate
14
by soldering the lead wires
13
upon the corresponding conductor patterns
15
. Such a mounting process used commonly in the art partly because of the fact that the soldering is conducts easily due to the low reflow temperature of the solder alloy and partly because of the fact that glass epoxy substrate is easily available with a low cost.
As already noted, the semiconductor device
11
includes a semiconductor chip encapsulated in the package body
12
formed of a resin, wherein the chip is held, inside the package body
12
, on a lead frame stage as usual. The semiconductor chip carries bonding pads thereon, and the bonding pads are interconnected to corresponding inner leads of the lead wires
13
by bonding wires.
Meanwhile, in order to further increase the mounting density of the semiconductor devices, a so-called multi-chip module structure is proposed, wherein a plurality of semiconductor chips are encapsulated in a single package body.
FIGS. 2A-2D
show the construction of a conventional multi-chip module in an elevational cross section.
Referring to
FIG. 2A
showing a conventional multi-chip module
21
A, the multi-chip module
21
A includes a chip mother board
22
a
carrying thereon a plurality of semiconductor chips
23
, wherein the semiconductor chips
23
are connected electrically to the chip mother board
22
a
by means of bonding wires
24
. It should be noted that the chip mother board
22
a
itself is held on a lead frame stage
25
and is connected electrically to inner leads
26
a
by the bonding wires
24
. The semiconductor chips
23
are encapsulated in a resin package body
27
together with the lead frame stage
25
and the chip mother board
22
a
as well as with the inner leads
26
a
, wherein outer leads
28
a
extend laterally from the package body
27
as an extension of the inner leads
26
a
. The outer leads
28
a
are thereby bent in the downward direction to form a J-shaped lead structure.
FIG. 2B
shows another multi-chip module
21
B that includes the semiconductor chips
23
in plural numbers on a chip mother board
22
b
, wherein the semiconductor chips
23
are connected electrically to the chip mother board
23
b
by means of the lead wires
24
, similarly to the device
21
A of FIG.
2
A. In the case of the device of
FIG. 2B
, on the other hand, the chip mother board
22
b
carries thereon inner leads
26
b
directly such that the inner leads
26
b
are held upon a lower major surface of the chip mother board
22
b
together with the semiconductor chips
23
. The semiconductor chips
23
are thereby encapsulated in the resin package body
27
together with the chip mother board
22
b
and the inner leads
26
b
, and outer leads
28
b
extend laterally from the resin package body
27
as an extension of the inner leads
26
b
. The outer leads
28
b
are thereby bent in the downward direction outside the package body
27
to form a gull wing lead structure.
FIG. 2C
shows a still other multi-chip module
21
C, wherein the device
21
C has a structure similar to that of the device
21
B of
FIG. 2B
, except that the upper major surface of the chip mother board
22
b
is exposed for contact with a heat sink
29
.
FIG. 2D
shows a still other multi-chip module
21
D, wherein the device
21
D has a structure similar to that of
FIG. 2B
except that each of the semiconductor chips
23
carries thereon bumps
23
a
for mounting upon a corresponding tape lead by way of the flip-chip process. Thus, the semiconductor chips
23
are mounted upon a corresponding tape lead
30
provided on the chip mother board
22
b
by the flip-chip process. In the illustrated example, the semiconductor chips
23
are mounted upon both upper and lower major surfaces of the chip mother board
22
b.
In the conventional single-chip device of
FIG. 1
in which the printed circuit board
14
carries thereon a plurality of components including the semiconductor device
11
, there has been a problem in that the size of the printed circuit board
14
tends to increase, and accordingly the length of the conductor patterns formed thereon. Thereby, the high speed operation of the electronic apparatus is substantially deteriorated. Such a single chip module further has a drawback in that one has to replace the whole printed circuit board when a failure has developed in any of the components on the board. Thereby, the cost of the electronic apparatus inevitably increases.
In the case of the multi-chip modules
21
A-
21
D of
FIGS. 2A-2D
, on the other hand, it should be noted that the interconnection between the semiconductor chips
23
and the chip mother board
22
a
or
22
b
is achieved by way of the bonding wire
24
or tape lead
30
. Thus, such a conventional construction has a drawback of increased length of wiring and corresponding deterioration of the operational speed. Further, construction of
FIGS. 2A-2D
has another drawback in that it requires extensive modification of the interconnection or replacement of components when a design change has occurred in the multi-chip module. In such conventional multi-chip modules, therefore, such a design change inevitably invites substantial increase in the number of the fabrication steps and hence a corresponding increase in the fabrication cost of the device.
SUMMARY OF THE INVENTION
Accordingly, it is a general object of the present invention to provide a novel and useful semiconductor device and a fabrication process thereof wherein the foregoing problems are eliminated.
Another and more specific object of the present invention is to provide a low cost semiconductor device having a high operational speed.
Another object of the present invention is to provide a semiconductor device, comprising:
a plurality of chip units each defined by a side wall and including a semiconductor chip, said plurality of chip units being arranged in a state such that a side wall of a chip unit abuts a corresponding side wall of an adjacent chip unit, each of said plurality of chip units including a plurality of terminals; and
interconnection means for interconnecting said plurality of terminals of a chip unit to corresponding terminals of an adjacent chip unit that abuts said chip unit at said respective side walls.
According to the present invention, it is possible to construct a flat multi-chip module of high performance with a substantially reduced thickness. Further, such a multi-chip module allows easy replacement of the chip unit as necessary, even when there occurs a change in the design

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