Electrical resistors – Resistance value responsive to a condition – Fluid- or gas pressure-actuated
Reexamination Certificate
1995-05-15
2001-02-06
Easthom, Karl D. (Department: 2832)
Electrical resistors
Resistance value responsive to a condition
Fluid- or gas pressure-actuated
C338S002000, C338S006000
Reexamination Certificate
active
06184774
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to semiconductor pressure detecting devices. More specifically, the present invention relates to semiconductor pressure detecting devices using the piezoresistance effect.
2. Description of Prior Art
FIG. 8
shows a schematic lateral cross section of a conventional semiconductor pressure detecting device, including a silicon chip
1
for converting measured pressure into a voltage and mounted on a pedestal, for example, a silicon pedestal
5
. The silicon pedestal
5
is arranged to relieve external stress imposed on the silicon chip
1
. The silicon pedestal
5
, on which the silicon chip has previously been die-bonded, is mounted on a stem
6
by die bonding. Arranged on this stem
6
is a pressure introduction pipe
7
for transmitting external pressure to the silicon chip
1
. The silicon chip
1
is electrically connected with an external apparatus via wires
8
wire-bonded to the silicon chip
1
, and leads
9
supported in the stem
6
with an insulating material
12
. The silicon chip
1
, wire
8
, and other elements are covered with a metallic cap
11
having a relief opening
10
.
In the conventional semiconductor pressure sensor, pressure introduced through the pressure introduction pipe
7
is applied to the silicon chip
1
, converted into voltage by the silicon chip
1
, and then output via the wire
8
and lead
9
.
FIG. 9
is a plan view showing the silicon chip
1
of the semiconductor pressure detecting device illustrated in
FIG. 8
, while
FIG. 10
is a side view of the silicon chip
1
. In these figures, the silicon chip
1
has a (100) crystalline surface. On the reverse side of the silicon chip
1
, a thin portion
2
is formed, and gauge resistances
3
a
to
3
d
are located on four corners of the surface of the silicon chip
1
corresponding to the thin portion
2
.
The conventional semiconductor pressure detecting device and its gauge resistances are formed as illustrated in FIG.
7
. Namely, by means of conventional laser recrystallization, a recrystallized silicon film
15
was produced in the (100) direction from seeds
13
and
14
by heating with a laser. However, a subgrain boundary
16
, a crystalline fault, occurs at the boundary of the recrystallized silicon film
15
. Conventionally, p-type gauge resistances
3
have been employed to avoid this subgrain boundary
16
.
In the semiconductor pressure detecting device described above, even if a gauge resistance is arranged in order to avoid a subgrain boundary, some subgrain boundaries are produced, resulting in non-uniform resistances of the gauge resistors, and also greatly non-uniform offset voltages. Further, the temperature coefficient of resistance is non-linear. Because of these problems, it is very difficult to compensate for the temperature characteristics of the semiconductor pressure detecting device and a high-precision semiconductor pressure detecting device cannot be provided.
SUMMARY OF THE INVENTION
The present invention avoids the problems of the prior art, and the object of the present invention is to produce highly-precise semiconductor pressure detecting devices without non-linearities in gauge resistance values.
According to a first aspect of the present invention, there is provided a semiconductor pressure detecting device including a silicon chip having a narrow central portion of one face, and several gauge resistances, each gauge resistance comprising a piezoresistance element made by laser crystallization and located adjacent to an edge of the narrow portion. The crystal face of the silicon chip has a (100) or equivalent orientation, and the gauge resistances are p-type conductivity gauge resistances arranged along (110) directions. Metal wiring is located on and crosses the subgrain boundaries.
According to a second aspect of the present invention, there is provided a semiconductor pressure detecting device including a silicon chip having a narrow central portion, and several gauge resistances, each gauge resistance comprising a piezoresistance element made by laser crystallization and located adjacent to an edge of the narrow portion on the other face. The crystalline face of the silicon chip has a (100) or equivalent orientation, and the gauge resistances are p-type conductivity gauge resistances arranged along (110) directions, and a high dopant impurity concentration p-type diffusion region is located adjacent to each of the subgrain boundaries.
According to a third aspect of the present invention, there is provided a semiconductor pressure detecting device equipped with a silicon chip having a narrow central portion and several gauge resistances, each gauge resistance comprising a piezoresistance element made by laser crystallization and located adjacent to an edge of the narrow portion on the other face. The face of the silicon chip has a (100) or equivalent orientation, and the gauge resistances are n-type resistances arranged along (110) directions, parallel to the subgrain boundaries.
According to a fourth aspect of the present invention, there is provided a semiconductor pressure detecting device including a silicon chip having a thin portion near the central portion of one face, and several gauge resistances, each gauge resistance comprising a piezoresistance element made by laser crystallization and located adjacent to the narrow portion. The face of the silicon chip has a (100) or equivalent orientation, and the gauge resistances are located along edges of the narrow portion in the shape of stairs with a subgrain boundary at each edge.
Other objects and advantages of the present invention will become apparent from the detailed description to follow taken in conjunction with the appended claims.
REFERENCES:
patent: 3137834 (1964-06-01), Pfann
patent: 3965453 (1976-06-01), Seidel et al.
patent: 4406992 (1983-09-01), Kurtz et al.
patent: 4439752 (1984-03-01), Starr
patent: 4579600 (1986-04-01), Shah et al.
patent: 4651120 (1987-03-01), Aagard
patent: 5047827 (1991-09-01), Clark, Jr. et al.
patent: 5471086 (1995-11-01), Ipposhi et al.
patent: 1405111 (1975-09-01), None
patent: 4-259744 (1994-04-01), None
Cook, The Theory of the Electromagnetic Field, p114 (1975).
Easthom Karl D.
Leydig , Voit & Mayer, Ltd.
Mitsubishi Denki & Kabushiki Kaisha
LandOfFree
Semiconductor pressure detecting device with piezo... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Semiconductor pressure detecting device with piezo..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semiconductor pressure detecting device with piezo... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2610664