JP2578148Y2 - Capacitive pressure sensor - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION In the present invention, a movable electrode is provided on a silicon substrate, a fixed electrode is provided on a glass substrate, and the silicon substrate and the glass substrate are joined with their respective electrode surfaces facing each other to form a sensor chip. It relates to a capacitance pressure sensor.

[0002]

2. Description of the Related Art As shown in FIG. 2A, a pressure sensor for absolute pressure, which is a conventional capacitance type pressure sensor, has a diaphragm portion 31 forming a movable electrode deformed by a measured pressure.
and a sensor chip 46a including a silicon substrate 33a having a cavity portion 32a provided thereunder and a glass substrate 35a having a fixed electrode 34a.

[0003] The sensor chip 46a includes a lead terminal 3
6a is adhered to the pedestal 37a on which the 6a is installed. The lead terminal 36a and the fixed electrode 34a are connected to the lead wire 3
8a. Sensor chip 46
a is a fixed electrode 34a provided on the glass substrate 35a.
The silicon substrate 33a and the glass substrate 3
A lateral hole 39a is formed between the lateral hole 39a and the hole 5a. This side hole 3
9a, a sealant 41a is disposed to isolate the cavity 32a from the sensor chip external world 40a. A cap 43a having a pressure introducing hole 42a is hermetically sealed on the pedestal 37a to which the sensor chip 46a is adhered.

FIG. 2B shows a gauge pressure sensor. The basic structure of this gauge pressure sensor is shown in FIG.
It is almost the same as the absolute pressure sensor shown in FIG.
The following points are different.

The glass substrate 35b constituting the sensor chip 46b and the pedestal 3 on which the sensor chip 46b is disposed
7b are formed with through holes 44b and 45b for introducing air. Other configurations are the same as those of the absolute pressure sensor, and therefore, the same portions are denoted by the same reference numerals and description thereof will be omitted.

Next, the operation principle of the capacitance type pressure sensor will be described. When pressure is applied to the diaphragm portions 31a, 31b constituting the movable electrode through the pressure introducing holes 42a, 42b, the diaphragm portions 31a, 31b are deformed. Due to the deformation, the diaphragm portion 31
The gap between the fixed electrodes 34a and 34b and the fixed electrodes 34a and 34b arranged opposite thereto changes. The diaphragm portions 31a, 31b and the fixed electrodes 34a, 34
The relationship between the gap between b and the capacitance is expressed by the following equation (1).

[0007]

(Equation 1)

As can be seen from Equation 1, the capacitance C changes due to the change in the gap d. There is also a certain correlation between pressure and gap. Therefore, pressure can be detected from a change in capacitance.

[0009]

However, in the case of the conventional structure, in the pressure sensor for absolute pressure, the cavity 3 is provided in the horizontal hole 39a for leading out the fixed electrode 34a.
In order to separate the inside of the sensor chip 2a from the outside of the sensor chip 40a, it is necessary to provide the sealant 41a. In the pressure sensor for gauge pressure, it is necessary to provide not only the sealant 41b but also the through holes 44b and 45b for introducing air into the glass substrate 35b and the pedestal 37b.

Therefore, the glass substrate 3 requiring high technology
The number of steps such as drilling of 5b and introduction of the sealants 41a and 41b increased, resulting in an increase in cost. In addition, when the sealants 41a and 41b are charged, the lead wires 3
There is a disadvantage that there is a risk of cutting 8a and 38b.

In view of the above drawbacks, the technical problem of the present invention is that there is no need to provide a sealant in a lateral hole between a silicon substrate and a glass substrate, and it is not necessary to provide an air introduction hole in a glass substrate. An object of the present invention is to provide a capacitance type pressure sensor.

[0012]

According to the present invention, a movable electrode is provided on a silicon substrate, a fixed electrode is provided on a glass substrate, and the silicon substrate and the glass substrate are joined with the movable electrode and the fixed electrode facing each other. To configure the sensor chip and install this sensor chip on the base member,
A capacitance pressure sensor that covers a cover member having a measurement pressure introduction hole, and measures pressure by utilizing that a capacitance between the movable electrode and the fixed electrode changes according to a measurement pressure. Forming a measurement pressure introduction side cavity portion in the cover member for providing a sealant between the silicon substrate and the cover member to communicate the measurement pressure introduction hole with the movable electrode. It is a feature.

[0013]

The sealant is provided between the silicon substrate and the cover member, and the measurement pressure side cavity for communicating the measurement pressure introduction hole with the movable electrode is formed in the cover member. It is no longer necessary to seal the side hole between them with a sealant, and the risk of cutting the lead wire during the sealing step is eliminated. Further, in the pressure sensor for gauge pressure, it is not necessary to provide an air introduction hole in the glass substrate.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a capacitance type pressure sensor according to the present invention.

FIGS. 1A and 1B are cross-sectional views showing a capacitance type sensor according to the present invention.
(A) shows a pressure sensor for measuring absolute pressure.

The absolute pressure measuring pressure sensor is composed of a silicon substrate 13a having a diaphragm portion 11a forming a movable electrode deformed by a measured pressure and a cavity portion 12a provided thereunder, and a glass substrate 1 having a fixed electrode 14a.
5a. The sensor chip 26a is adhered on a pedestal 17a as a base member on which the lead terminals 16a are arranged. The lead terminal 16a and the fixed electrode 14a are electrically connected by a lead wire 18a. A cap 20a as a cover member having a pressure introduction hole 19a for introducing a measurement pressure is hermetically sealed on the pedestal 17a to which the sensor chip 26a is adhered.

The silicon substrate 1 of the sensor chip 26a
A sealant 21a is disposed between the 3a side and the cap 20a. The sealant 21a is in close contact with the inner surfaces of the silicon substrate 13a and the cap 20a. The sealing agent 21a separates the pressure introduction side cavity portion 22a from the other cap inner region 23a. The pressure introduction side cavity portion 22a has a pressure introduction hole 19 for introducing a measurement pressure.
a and the diaphragm portion 31a as the movable electrode. Further, the pressure introduction side cavity portion 22
A region 23a inside the cap other than a is sealed with a sealant 21a. The step of arranging the sealant 21a between the silicon substrate 13a side of the sensor chip 26a and the cap 20a is performed in advance by sealing the sealant 21a with the sensor chip 26a.
By arranging it on the side of the cap 20a or the cap 20a, it is performed simultaneously with the hermetic sealing step of the pedestal 17a and the cap 20a.

FIG. 1B shows a gauge pressure sensor. The basic structure of the pressure sensor for gauge pressure is almost the same as that of the pressure sensor for absolute pressure measurement, except for the following points. That is, the pedestal 17b on which the sensor chip 26b is disposed
Is provided with a through hole 24b for introducing air. The sensor cavity 12b communicates with the atmosphere via the through hole 24b and the cap inner region 23a. Since other structures are the same as those of the absolute pressure measuring pressure sensor shown in FIG. 1A, the same portions are denoted by the same reference numerals and the description thereof will not be repeated.

As described above, the sealants 21a and 21b are replaced with the silicon substrates 13a and 13b of the sensor chips 26a and 26b.
By providing between the side and the caps 20a and 20b,
It is possible to separate the pressure between the pressure introduction side cavity portions 22a and 22b and the other cap inner regions 23a and 23b. As a result, it is not necessary to seal the lateral holes 25a, 25b for drawing out the fixed electrodes 14a, 14b on the glass substrates 15a, 15b, and the danger of cutting the lead wire at the time of sealing is eliminated. Further, with respect to the pressure sensor for gauge pressure, it is not necessary to provide a through hole for introducing air into the glass substrate 15b side of the sensor chip 46b, and the pressure sensor for gauge pressure can be manufactured without using advanced technology of glass drilling. Can be.

[0020]

As described above, according to the present invention, the sealant is provided between the silicon substrate and the cover member to cover the measurement pressure introduction side cavity for communicating the measurement pressure introduction hole with the movable electrode. Since it is formed in the member, there is no need to seal the side holes that may cause cutting of the lead wire, and it is not necessary to perform glass drilling that requires advanced technology, making it easy and inexpensive to manufacture. An electrostatic capacitance sensor for absolute pressure and gauge pressure can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a capacitance type pressure sensor according to the present invention, in which (a) shows a pressure sensor for measuring absolute pressure, and (b) shows a pressure sensor for measuring gauge pressure. Is shown.

FIG. 2 is a sectional view showing a conventional capacitance type pressure sensor, in which (a) shows a pressure sensor for measuring absolute pressure,
(B) shows a pressure sensor for measuring gauge pressure.

[Explanation of symbols]

 11a, 11b Diaphragm part 12a, 12b Cavity part (sensor part) 13a, 13b Silicon substrate 14a, 14b Fixed electrode 15a, 15b Glass substrate 16a, 16b Lead terminal 17a, 17b Base 18a, 18b Lead wire 19a, 19b Pressure introduction hole 20a, 20b Cap 21a, 21b Sealant 22a, 22b Cavity part (pressure introduction side) 23a, 23b Inner cap area 24b Atmospheric introduction hole 25a, 25b Fixed electrode lead-out lateral hole 26a, 26b Sensor chip 31a, 31b Diaphragm part 32a , 32b Cavity part (sensor part) 33a, 33b Silicon substrate 34a, 34b Fixed electrode 35a, 35b Glass substrate 36a, 36b Lead terminal 37a, 37b Base 38a, 38b Lead wire 3 a, 39 b fixed electrode drawing-out side holes 40a, 40b outside the chip regions 41a, 41b sealants 42a, 42b pressure introducing hole 43a, 43b cap 44b air introducing hole (base) 45b air introducing hole (glass substrate) 46a, 46b the sensor chip

Claims (1)

(57) [Scope of request for utility model registration] A movable electrode is provided on a silicon substrate.
A fixed electrode is provided on a glass substrate, a sensor chip is formed by joining the silicon substrate and the glass substrate with the movable electrode and the fixed electrode facing each other, and a sensor chip is mounted on the base member. A capacitance pressure sensor that covers a cover member having a thickness of the silicon substrate, and measures a pressure by utilizing that a capacitance between the movable electrode and the fixed electrode changes according to a measurement pressure. A measurement pressure introduction side cavity portion for providing a sealant between the cover member and the measurement pressure introduction hole and the movable electrode so as to communicate with each other, is formed in the cover member. Capacitive pressure sensor.