Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – Insulating material
Reexamination Certificate
2001-07-13
2004-04-13
Eckert, George (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
Insulating material
C257S701000, C257S675000, C257S717000, C257S796000
Reexamination Certificate
active
06720650
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to a semiconductor device in which a semiconductor chip such as a chip size package or a flip chip is provided with a heat spreader for radiation of heat and the method of manufacturing the same.
2. Description of the Related Art
In recent years, in the multimedia society, accompanying with rapid increment of an information amount and development of an electronic equipment, high integration and high-speed of an electronic component are proceeded and at the same time, miniaturization of a semiconductor device is proceeded, and then miniaturization of a chip size package (hereinafter, referred as CSP) which has the nearly same size as a semiconductor chip and a flip chip (hereinafter, referred as FC) is proceeded.
However, according to high densification of a semiconductor device in recent years, heat generation in the operation becomes increased, thereby, in order to suppress the generation of heat of the semiconductor device, an essential improvement such as decrease of an operating voltage and design for decreasing a current loss is required. At the same time, a counterplan has been performed in which a fan is provided to forcibly cool the semiconductor device or a heat spreader for radiation of heat and a radiating fin are provided.
FIGS. 1A
to
1
D show methods for providing a heat spreader in a conventional FC in the process sequence.
First, as shown in
FIG. 1A
, a FC product
100
is fixed to a predetermined position on a working table
101
.
Then, as shown in
FIG. 1B
, an Ag paste
103
stored in a syringe
102
is dropped and applied to the FC product
100
by a predetermined amount. At this time, according to the shape of the heat spreader to be mounted later, the position for applying the Ag paste
103
and the number of the applications (dropping) become different.
Then, as shown in
FIG. 1C
, the FC product
100
applied with the Ag paste
103
is mounted to a thermal bonding tool
104
of a thermal bonding apparatus. Also, a heat spreader
106
or a heat spreader attached with a support ring is mounted on a heat table
105
. The heat spreader
106
is made of aluminum, copper or alloy thereof.
Subsequently, as shown in
FIG. 1D
, the FC product
100
is tightly pressed to the heat spreader
106
heated by the heat table
105
by the thermal bonding tool
104
, the Ag paste
103
is heated and pressed to be cured, and the FC product
100
and the heat spreader
106
are heated and compressed. Thereby, the heat spreader
106
composed of aluminum, copper, or alloy thereof is attached to the FC product
100
.
However, since the difference of thermal expansive coefficient between the heat spreader
106
and the semiconductor chip (the FC product
100
) is large, a stress generated between the heat spreader
106
and the semiconductor chip can be relaxed in order to directly attach the heat spreader
106
composed of aluminum, copper, or alloy thereof with an excellent heat radiation property to the semiconductor chip, and moreover, an adhesive which has a heat resistance, an electrolytic corrosion resistance and a moisture proof and has less deterioration in case that the moisture proof test is performed under the strict condition such as, particularly, the PCT (Press Cooker Test) process is required. However, a liquid adhesive has a problem that attention to the preservation stability of the adhesive must be paid and a problem that the operating efficiency is deteriorated in comparison with a LOC (Lead On Chip). Also, since a silver paste has a problem that a silver filler is precipitated, there is a problem that dispersion of the silver filler is not uniformed.
Also, as problems related to the process, in case the thermal bonding method, since the semiconductor chip and the heat spreader are bonded with large load of several tens kg, the thermal boding tool
104
often gives damages to the semiconductor chip. Particularly, in case that the thermal bonding tool
104
is contacted to a solder resist layer of the semiconductor chip surface, there is a problem that stripping of the solder resist layer is easily occurred.
Also, in case that the support ring is connected to the heat spreader, since the area of the support ring is large, the time for the thermal bond is needed, and then there is a difficulty that the index time for the process is long. And, since the Ag paste is used, there is a defect that the cost is expensive.
SUMMARY OF THE INVENTION
Thus, the object of the present invention is to provide a method of manufacturing a semiconductor device which is not subjected to restriction by a stress due to the difference of thermal expansive coefficient between a heat spreader and a semiconductor chip, does not need to consider preservation stability of an adhesive and an uniform dispersion of a filler, does not need a thermal bonding tool to avoid damages of the semiconductor chip due to that, and accomplishes the quickness of the process time.
A semiconductor device having a heat spreader attached thereto according to a first aspect of the present invention comprises a substrate; a semiconductor chip mounted on the substrate; an insulating resin layer for sealing the side of the semiconductor chip on said substrate; and a copper paste film contacted to the exposed surface of the surface of said semiconductor chip, wherein said copper paste film functions as a heat spreader.
A semiconductor device having a heat spreader attached thereto according to a second aspect of the present invention comprises a semiconductor chip; and a copper paste film formed to be contacted to the surface of the semiconductor chip, on which a wiring is not formed. Said copper paste film is cut and separated at the same time when said semiconductor chips are individually divided from a semiconductor wafer. Said copper paste film functions as a heat spreader.
In the semiconductor device having a heat spreader attached thereto of the first and the second aspects of the present invention, said copper paste film is formed by applying a copper paste, or said copper paste film is supplied as a copper paste film coated on a sheet base material.
Also, said copper paste film has irregularities on the surface to which said semiconductor chip is not contacted, to extend the radiation area.
A method of manufacturing a semiconductor device having a heat spreader attached thereto according to a third aspect of the present invention comprises the steps of mounting a plurality of semiconductor chips on a substrate; sealing said substrate between said semiconductor chips with an insulating resin; and forming a copper paste film as a heat spreader on the exposed surface of said semiconductor chip and on said insulating resin.
A method of manufacturing a semiconductor device having a heat spreader attached thereto according to a fourth aspect of the present invention comprises the steps of forming a copper paste film as a heat spreader on the surface of said semiconductor wafer, on which a wiring layer is not formed, said semiconductor wafer having said wiring layer on other surface and a semiconductor element; and dividing said semiconductor wafer into a plurality of individual chips, thereby, at the same time, separating said copper paste film into individual copper films on the semiconductor chips.
In the method of manufacturing a semiconductor device having a heat spreader attached thereto of the third aspect of the present invention, said substrate is a multi-layer wiring substrate and a gap between said semiconductor chip and said multi-layer wiring substrate is sealed with the insulating resin in said step of mounting the semiconductor chips. Also, the steps of sealing said substrate between said semiconductor chips with the insulating resin includes supplying the insulating resin to a gap between said semiconductor chips by using capillary phenomenon, supplying the insulating resin by injection, or supplying the insulating resin by transfer. Also, the steps of curing said copper paste film so as to be sol
Chu Chris C.
Eckert George
NEC Electronics Corporation
Scully Scott Murphy & Presser
LandOfFree
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