Semiconductor device manufacturing: process – Making device or circuit responsive to nonelectrical signal – Physical stress responsive
Reexamination Certificate
2000-03-30
2001-10-09
Smith, Matthew (Department: 2825)
Semiconductor device manufacturing: process
Making device or circuit responsive to nonelectrical signal
Physical stress responsive
C438S424000, C438S051000, C438S053000, C438S054000, C438S055000, C438S106000, C257S666000, C257S676000, C257S678000
Reexamination Certificate
active
06300155
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of Japanese Patent Application No.
11-89789
filed on Mar. 30, 1999, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for producing a semiconductor device including semiconductor chips such as a pressure sensor by coating electrodes and wires with a thin film.
2. Description of the Related Art
A semiconductor chip such as a pressure sensor is mounted on an electronic part and is electrically connected to electrodes of the electronic part via wires. The wires and the electrodes are usually coated with a thin film not to be exposed, thereby preventing corrosion of the wires and the electrodes.
The thin film is deposited on the electronic part to coat the electrodes and the wires in a state in that only the semiconductor chip and a vicinal region around the chip is exposed from an opening portion of a mask member (frame) disposed on the electronic part. This is because the thin film must be prevented from being deposited on the other region of the electronic part than the exposed region, which has members to be electrically connected to external units.
Specifically, as shown in
FIG. 11
, in a pressure sensor assembly (semiconductor device), after a pressure sensor element
101
is installed in a resin-made housing
102
, a wire
104
is bonded to a lead portion
103
insert-molded in the housing
102
. Then, an organic deposition film is formed to coat the wire
104
and the lead portion
103
as indicated by a dotted line in FIG.
11
. At that time, it is necessary to prevent the thin film from being deposited on the other region than the region where the sensor element
101
is mounted, because the other region (for instance, connector portion
102
a
) must provide electrical connection with external units.
SUMMARY OF THE INVENTION
In the method in which the other region of the electronic part is covered with the mask member, the thin film deposited on the mask member needs to be removed from the mask member so that the mask member can be reused. This is because, when the same mask member is reused to perform the above thin film coating step many times to many electronic parts, the thin film is deposited on the mask member every time and may be separated from the mask member during one thin film coating step accordingly. The separated thin film can be attached to the exposed region of the electronic part as contaminant, resulting in deterioration of semiconductor device characteristics (for instance, lessened sensitivity of the pressure sensor). The removal of the thin film from the mask member is, however, difficult, because the thin film is closely adhered to the mask member.
The present invention has been made in view of the above problems. An object of the present invention is to provide a method of readily removing a thin film from a mask member used for producing a semiconductor device.
According to a first aspect of the present invention, a mask member covers an electronic part with an opening portion, an inner wall of which is covered with a hollow packing member so that a hollow portion of the packing member exposes a specific region of the electronic part. The mask member is further covered with a cover member. In this state, a thin film is formed to coat the specific region through the hollow portion.
Because the mask member is covered with the packing member and the cover member, the thin film is not adhered to the mask member. Accordingly, after detaching the electronic part and the cover member from the mask member, the mask member can be reused to form the thin film on another electronic part successively.
According to a second aspect of the present invention, an electronic part is covered with a mask member, and a thin film is formed to coat a specific region of the electronic part through an opening portion of the mask member. After that, the thin film adhered to the mask member is removed so that the mask member can be reused. In this case, a first surface of the mask member to which the thin film is adhered when the thin film is formed has a surface roughness smaller than a specific surface roughness.
A supplementary film may be formed on the mask member before the thin film is formed so that the supplementary film is interposed between the mask member and the thin film. A bonding strength between the supplementary film and the thin film is smaller than that between the mask member and the thin film. As a result, the thin film can be readily removed from the mask member to be reused.
REFERENCES:
patent: 4821148 (1989-04-01), Kobayashi et al.
patent: 5948991 (1999-09-01), Nomura et al.
patent: 6025640 (2000-02-01), Yagi et al.
patent: 6034421 (2000-03-01), Tokunaga
patent: 6117513 (2000-09-01), Hotta et al.
patent: 6162657 (2000-12-01), Schiele et al.
patent: 63081964-A (1988-04-01), None
patent: 02298077-A (1990-12-01), None
U.S. application No. 08/982,034, Tokunaga, filed Dec. 1, 1997.
U.S. application No. 09/417,301, Watanabe et al., filed Oct. 13, 1999.
Handa Ryoichi
Taki Takafumi
Denso Corporation
Law Office of David G. Posz
Smith Matthew
Yevsikov V.
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