Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor
Reexamination Certificate
2002-04-25
2004-04-06
Nelms, David (Department: 2818)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
C438S121000, C438S123000, C438S125000, C257S666000, C257S678000, C257S782000
Reexamination Certificate
active
06716667
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing the same, and more specifically to a structure of a semiconductor device having a semiconductor chip fixed on a lead frame, and a method of manufacturing the same.
2. Description of the Background Art
FIG. 11
is a perspective view schematically showing a semiconductor chip to be fixed on a lead frame in a method of manufacturing a conventional semiconductor device. Referring to
FIG. 11
, conventionally, a semiconductor chip
105
is fixed using a die bonding material
102
on an island portion
101
a
of a lead frame
101
, which has island portion
101
a
and a lead portion
101
b.
A cross section of a semiconductor device thus manufactured has a structure shown in
FIG. 12
, after resin sealing. Referring to
FIG. 12
, semiconductor chip
105
is fixed on island portion
101
a
by means of die bonding material
102
. The bonding pad (not shown) of this semiconductor chip
105
is electrically connected with lead portion
101
b
using a bonding wire
106
. Island portion
101
a
, die bonding material
102
, semiconductor chip
105
and bonding wire
106
are sealed with mold resin
107
. Only a plurality of lead portions
101
b
protrude from mold resin
107
for electrical connection with the outside.
As described above, die bonding material
102
is conventionally used to fix semiconductor chip
105
on lead frame
101
. Solder material or adhesive is usually used as die bonding material
102
. Usually, solder consisting of Pb (lead)-Sn (tin) alloy is used for this solder material, and lead is thus contained.
Lead intake may cause nerve disorder or disturbance of reproduction system. Moreover, lead may cause anemia or hypertension and is suspected of being a carcinogenic metal. Therefore, if electronic equipment products including solder are disposed of, lead contained in solder may melt into and contaminate soil or underground water to adversely affect human bodies, thus resulting in an environmental problem.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a semiconductor device in which a semiconductor chip can be fixed on a lead frame without using a die bonding material, and a method of manufacturing the same. As a result, it becomes possible to provide a semiconductor device capable in which a semiconductor chip can be fixed on a lead frame without using lead (that is, lead-free), and a method of manufacturing the same.
A semiconductor device in accordance with the present invention includes a semiconductor substrate having a main surface, and a semiconductor chip arranged on the main surface of the substrate, wherein a space kept airtight is provided between the main surface of the substrate and the semiconductor chip, and the semiconductor chip is supported on the substrate by making negative the atmospheric pressure in the space relative to the atmospheric pressure outside the semiconductor device.
In the semiconductor device according to the present invention, the semiconductor chip is fixed on the substrate by making negative the atmospheric pressure in the space between the substrate and the semiconductor chip relative to the atmospheric pressure outside the semiconductor device. Accordingly, the semiconductor chip can be fixed on the substrate even without using a die bonding material. This can eliminate the problem of lead contained in solder that is commonly used as a die bonding material.
Preferably, the above-described semiconductor device further includes a seal member arranged between the substrate and the semiconductor chip in order to keep the space airtight.
The space between the semiconductor chip and the substrate can be kept airtight by using the seal member in this way.
In the above-described semiconductor device, it is preferable that a groove for fitting-in the seal member is formed on the main surface of the substrate.
Therefore, it is possible to fit and fix the seal member in the groove.
In the above-described semiconductor device, it is preferable that the substrate is directly in contact with the semiconductor chip, and at least that part of the substrate which is in contact with the semiconductor chip has a mirror surface.
Since that surface of the substrate which is in contact with the semiconductor chip has a mirror surface, the contact parts of the semiconductor chip and the substrate can be tightly connected and the space therebetween can be kept airtight.
In the above-described semiconductor device, it is preferable that a depressed portion to form a part of the space is formed on the main surface of the substrate.
Therefore, the space can easily be formed between the semiconductor chip and the substrate.
A method of manufacturing a semiconductor device according to the present invention includes the following steps.
The semiconductor chip is laid on the substrate in such a temperature environment that is higher than a temperature at a resin sealing step, such that a space kept airtight is created between the substrate and the semiconductor chip. After the semiconductor chip is laid on the substrate, the atmospheric pressure in the space is made negative relative to the external atmospheric pressure by lowering an ambient temperature, so that the semiconductor chip is fixed on the substrate.
In the method of manufacturing the semiconductor device according to the present invention, the semiconductor chip is fixed on the substrate by making negative the atmospheric pressure in the space between the substrate and the semiconductor chip relative to the atmospheric pressure outside the semiconductor device. Therefore, the semiconductor chip can be fixed on the substrate without using a die bonding material. This can eliminate the problem of lead contained in solder commonly used as a die-bonding material.
Furthermore, since the semiconductor chip is fixed on the substrate in such a temperature environment that is higher than a temperature at a resin sealing step, the atmospheric pressure in the space between the semiconductor chip and the substrate can remain negative relative to the external atmospheric pressure, even when heated at a highest temperature at the resin sealing step after the semiconductor chip being laid on the substrate. Therefore, the semiconductor chip remains fixed on the substrate even at the resin sealing step.
In the method of manufacturing the above-described semiconductor device, it is preferable that the step of laying the semiconductor chip on the substrate and the step of supporting the semiconductor chip on the substrate with lowered ambient temperature are performed in a one atmospheric pressure (1 atm) environment.
Accordingly, even in a high temperature environment when the semiconductor chip is laid on the substrate, the pressure in the airtight space can be 1 atm. Therefore, with the subsequent temperature drop, the atmospheric pressure in the airtight space can be decreased to be lower than 1 atm, that is, negative relative to the external atmospheric pressure (1 atm).
In the method of manufacturing the above-described semiconductor device, it is preferable that the 1 atm pressure environment is obtained in a high-temperature chamber of a structure having a portion open to the outside, so that the pressure inside thereof is always kept at 1 atm.
Thus, the 1 atm pressure environment can be created in a high-temperature chamber of a simple structure.
In the method of manufacturing the above-described semiconductor device, it is preferable that the 1 atm pressure environment is obtained in a high-temperature chamber of such a structure that allows variation in its capacity to maintain internal pressure at 1 atm.
Thus, the 1 atm pressure environment can be created in a high-temperature chamber of a simple structure.
In the method of manufacturing the above-described semiconductor device, it is preferable that the step of laying the semiconductor chip on the substrate and the step of fixing the semiconductor chip on the substrate with lowered a
Nelms David
Renesas Technology Corp.
Tran Long
LandOfFree
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