Method of producing vacuum container

Semiconductor device manufacturing: process – Making device or circuit responsive to nonelectrical signal – Physical stress responsive

Reexamination Certificate

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C438S115000, C438S126000, C438S127000, C438S055000

Reexamination Certificate

active

06479314

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of producing a vacuum container by using anode-coupling.
2. Description of the Related Art
FIG. 3
shows an example of a vacuum container schematically in cross-section. The vacuum container
1
shown in
FIG. 3
comprises a base layer (e.g., glass layer)
2
, a semiconductor layer (e.g., silicon layer)
3
, and a lid layer (e.g., glass layer)
4
. The base layer
2
, the semiconductor layer
3
, and the lid layer
4
are laminated and integrated sequentially in that order to produce a laminate
5
. Concavities
2
a
and
4
a
are formed in the base layer
2
and the lid layer
4
in the positions thereof opposed to each other through the semiconductor layer
3
. These concavities
2
a
and
4
a
form a vacuum cavity
6
inside the laminate
5
.
A vibrator
7
, for example, obtained by processing the semiconductor substrate constituting the semiconductor layers
3
is received in the vacuum cavity
6
. The vibrator
7
, received and disposed in the vacuum cavity
6
, can be satisfactorily vibrated without suffering no damping by air.
FIG. 4
is a perspective view showing an example of the semiconductor layer
3
, together with the base layer
2
. The semiconductor layer
3
has a vibrator formed by processing the semiconductor substrate. The semiconductor layer
3
shown in
FIG. 4
is formed by using a technique such as etching or the like. A sensor unit
8
containing the vibrator
7
, and a sealing portion
9
surrounding the sensor unit
8
are formed in the semiconductor layer
3
. The sealing portion
9
is sandwiched between the base layer
2
and the lid layer
4
from the upper and lower sides thereof shown in
FIG. 4
, respectively. The sealing portion is anode-coupled to the base layer
2
and the lid layer, respectively. Thus, the sealing portion
9
air-tightly seals the vacuum cavity
6
for containing the sensor unit
8
.
The sensor unit
8
shown in
FIG. 4
, which constitutes an angular velocity sensor, comprises the quadrangular vibrator
7
, vibrator supporting fixing portions
10
(
10
a
,
10
b
,
10
c
, and
10
d
), electrode supporting-fixing portions
11
(
11
a
and
11
b
), a detection electrode pad forming portion
12
, beams
13
(
13
a
,
13
b
,
13
c
, and
13
d
), interdigital movable electrodes
14
(
14
a
and
14
b
), and interdigital fixed electrodes
15
(
15
a
and
15
b
).
The vibrator supporting fixing portions
10
(
10
a
,
10
b
,
10
c
, and
10
d
), the electrode supporting-fixing portions
11
(
11
a
and
11
b
), and the detection electrode pad forming portion
12
are anode-coupled and fixed to the base layer
2
and the lid layer
4
. The vibrator
7
is connected to and is communicated with the vibrator supporting fixing portions
10
(
10
a
,
10
b
,
10
c
, and
10
d
) via the beams
13
(
13
a
,
13
b
,
13
c
, and
13
d
), respectively. Moreover, the interdigital movable electrodes
14
(
14
a
and
14
b
) are formed so as to protrude from the ends of the vibrator
7
in the X-direction in FIG.
4
. The interdigital fixed electrodes
15
(
15
a
and
15
b
) are formed so as to extend from the electrode supporting-fixing portions
11
(
11
a
and
11
b
) in the X-direction in such a manner as to mesh with the interdigital movable electrodes
14
at an interval from the interdigital movable electrodes
14
.
The concavities
2
a
and
4
a
, shown in
FIG. 3
, are formed in the base layer
2
and the lid layer
4
in the positions thereof which are opposed to the area of the semiconductor layer
3
in which the vibrator
7
, the beams
13
(
13
a
,
13
b
,
13
c
, and
13
d
), and the interdigital movable electrodes
14
(
14
a
and
14
b
) are formed. In the concavities
2
a
and
2
b
, the vibrator
7
, the beams
13
(
13
a
,
13
b
,
13
c
, and
13
d
), and the interdigital movable electrodes
14
(
14
a
and
14
b
) are movably lifted from the base layer
2
and the lid layer
4
.
Electrode pads (not shown), which are metal films, are formed on the upper faces of the vibrator supporting fixing portions
10
(
10
a
,
10
b
,
10
c
, and
10
d
), the electrode supporting-fixing portions
11
(
11
a
and
11
b
), and the detection electrode pad forming portion
12
, respectively. Perforations are formed in the lid layer
4
in the positions thereof opposed to the electrode pads, respectively. Thus, the electrode pads are exposed to the exterior, and can be electrically connected to an external circuit by wire-bonding or the like.
A detection electrode (not shown) is formed on the bottom of the concavity
2
a
of the base layer
2
in the position thereof opposed to the vibrator
7
at an interval therefrom. Moreover, a wiring pattern
16
for connecting the detection electrode and the detection electrode pad forming portion
12
to each other is formed on the base layer
2
.
Referring to the sensor unit
8
shown in
FIG. 4
, when an AC current for driving is applied from the external circuit to the fixed electrodes
15
a
and
15
b
, for example, the electrostatic forces between the fixed electrode
15
a
and the movable electrode
14
a
and that between the fixed electrode
15
b
and the movable electrode
14
b
are changed depending on the above-mentioned AC voltage, so that the vibrator
7
is driven and vibrated in the X-direction shown in FIG.
4
. If the vibrator
7
is rotated on the Y-axis while it is being driven and vibrated as described above, a Coriolis force is generated in the Z-direction. The Coriolis force is added to the vibrator
7
, so that the vibrator
7
is vibrated in the Z-direction to be detected.
The vibration of the vibrator
7
in the Z-direction changes the interval between the vibrator
7
and the detection electrode to change, so that the electrostatic capacity between the vibrator
7
and the detection electrode is changed. The change in the electrostatic capacity is output from the detection electrode to the exterior via the wiring pattern
16
and the electrode pad. The angular velocity or the like of the rotation of the vibrator
7
on the Y-axis can be determined based on the detected value.
Referring to a process of producing the vacuum container
1
containing the vibrator
7
(sensor unit
8
) shown in
FIG. 4
, for example, a base for forming a plurality of the base layers
2
, a semiconductor substrate for forming a plurality of the semiconductor layers
3
, and a lid material for forming a plurality of the lid layers
4
are sequentially laminated and integrated to produce a laminate. The laminate is divided into the areas for forming the vacuum containers, which are separated into the individual vacuum containers. Hereinafter, an example of the process of producing the vacuum container
1
will be described in detail with reference to
FIGS. 5A
to
5
F.
FIGS. 5A
to
5
F show the site corresponding to the part of the vacuum container taken along line A—A in
FIG. 4
, respectively.
First, a base
20
for forming a plurality of the base layers
2
is prepared as shown in FIG.
5
A. The concavities
2
a
are formed in the predetermined areas of the base
20
for forming the respective base layers
2
. The detection electrode and the wiring pattern
16
are formed on the inner wall of each concavity
2
a
by a technique such as sputtering or the like. Then, a semiconductor substrate
21
is placed on the upper side of the base
20
in such a manner as to close the openings of the concavities
2
a
, as shown in FIG.
5
B. The base
20
and the semiconductor substrate
21
are anode-coupled to each other. Then, the semiconductor substrate
21
is surface-ground till a predetermined thickness. Thereafter, the upper side of the semiconductor substrate
21
is polished to have a mirror-like surface as shown in FIG.
5
C.
After this, the semiconductor substrate
21
is processed by using such a technique as etching, photolithography, or the like, as shown in FIG.
5
D. The semiconductor substrate
21
is processed to form the semiconductor layers
3
of a plurality of the vacuum containers
1
. In

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