JPH1062283A - Electrostatic capacitance type pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sensor with a shorter making process and higher yields by forming an insulation film on a glass substrate in all areas except a fixed electrode drawing pattern pad part to join the glass substrate and a silicon substrate through the insulation film. SOLUTION: A fixed electrode 21, a fixed electrode drawing pattern 22 and a fixed electrode drawing pattern pad part 26 are arranged on a glass substrate 20. An insulation film 25 is formed in all areas except the fixed electrode drawing pattern pad part 26. A mobile electrode pad part 23 is arranged on the insulation film 25 and in addition to this, a conductor film 24 is arranged thereon at the peripheral part of the fixed electrode 21, on the fixed electrode drawing pattern part 22 and between the fixed electrode drawing pattern part 22 and the mobile electrode pad part 23. In the structure, the fixed electrode 21 is covered entirely with the insulation film 25 and this can prevent dew concentration on the surface of the fixed electrode 21 and an eventual short-circuiting between the electrodes as caused by the infiltration of impurities such as moisture or dust in the atmospheric air into a cavity part. This also enables the setting of the thickness of the insulation film 25 optionally thereby securing the insulation of the pattern 22 and the conductor film 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitance type pressure sensor in which electrodes are formed on a silicon substrate and an insulating substrate, and the respective electrode surfaces are joined to face each other.

[0002]

2. Description of the Related Art As this kind of capacitance type pressure sensor,
Generally, a pressure sensor shown in FIG. 3 is known. FIG.
FIG. 3A is a perspective view showing a state in which a cap is removed to expose the inside, and FIG. 3B is a sectional view. FIG.
Is a sensor chip 3 of the capacitance type pressure sensor shown in FIG.
FIG. 4A is a development view showing a configuration of a part 0, and FIG.
FIGS. 4B and 4C are cross-sectional views of FIGS. AA and BB, respectively.

In a conventional capacitance type pressure sensor, as shown in FIGS. 3 and 4, a silicon substrate 10 has a diaphragm portion 11 functioning as a movable electrode deformed in response to pressure.
Are formed, and a fixed electrode 21, a fixed electrode lead pattern 22, a fixed electrode lead pattern pad portion 26, and a movable electrode pad 23 are formed in a continuous pattern on a glass substrate 20, which is an insulating substrate. The silicon substrate 10 and the glass substrate 20 are joined at a part thereof, whereby the cavity 12 is formed below the diaphragm 11.

The sensor chip 30 composed of the silicon substrate 10 and the glass substrate 20 has a fixed hole 13
Thus, the fixed electrode 21 is drawn out of the cavity 12 through the fixed electrode drawing pattern 22 and the fixed electrode drawing pattern pad 26. The diaphragm part 11 also serving as a movable electrode is pressure-bonded through the silicon substrate 10 to a movable electrode pad 23 provided on a glass substrate 20, and is taken out of the cavity part 12 as an electrode.

Further, a parasitic capacitance which changes due to a detected pressure which flows from the periphery of the diaphragm portion 11 functioning as a movable electrode and the fixed electrode 21 and a parasitic capacitance which does not change due to the detected pressure generated by the extraction pattern 22 of the fixed electrode and the like. As shown in FIG. 4A, a conductor film 24 is disposed around the fixed electrode 21, on the fixed electrode lead-out pattern portion 22, and between the movable electrode pad portions 23 as a guard for suppressing the above. Further, as shown in FIG. 4 (b), in order to electrically isolate the fixed electrode lead-out pattern 22 and the conductor film 24, between the fixed electrode lead-out pattern 22 and the conductor film 24, and as shown in FIG. 4 (c). In addition, an insulating film 25 is provided on the entire surface under the conductor film 24 on the fixed electrode 21.

Here, a conventional method for manufacturing an insulating film and a conductive film is shown in FIG. This will be described with reference to a process diagram of the AA cross section in FIG. A protective film 50 for protecting the glass substrate 20 is patterned in a region outside the pattern on the glass substrate 20 on which the fixed electrodes 21 and the like are formed [FIG.
(A)]. Next, an insulating film 25 and a conductor film 24 are formed over the entire surface by sputtering [FIG. 5B]. Next, a resist pattern of the conductor film 24 is formed using the photoresist 51, and thereafter, a pattern of the conductor film is formed by an etching method (FIG. 5C). Next, a resist pattern 52 of the insulating film 25 is formed in the same manner as the conductive film 24,
A pattern of the insulating film 25 is formed (FIG. 5D). Finally, the protective film 50 is removed [FIG. 5 (e)].

By the above method, the conductor film 24 and the insulating film 25
The sensor chip 30 shown in FIG. 3 on which is formed is adhered on a base 40 as a base member. The pedestal 40 is provided with lead terminals 44, 45, 46, and the lead terminals 44, 45, 46 and the fixed electrode 2 on the glass substrate 20.
1. The movable electrode pad 23 and the conductor film 24 are electrically connected by lead wires 33, 34, 35.

[0008] Atmospheric pressure introduction through holes 31 and 43 are formed in the glass substrate 20 and the pedestal 40, respectively.
These two atmospheric pressure introduction holes 31, 43 are communicated. In order to isolate the cavity portion 12 from the cap inner region 47 outside the sensor chip, the fixed electrode lead-out lateral hole 13 is sealed with a sealant 32. Then, the pedestal 40 and the cap 41 as a cover member provided with the through-hole 42 for introducing a measured pressure are sealed by a hermetic seal, and a capacitance type pressure sensor is completed.

The principle of operation of the capacitance type pressure sensor is that when pressure is applied to the diaphragm portion 11 which also serves as a movable electrode, the diaphragm portion 11 which is a movable electrode is deformed, and the diaphragm portion 11 and the fixed electrode 21 opposed to the diaphragm portion 11 are deformed. Changes in the gap between occur. At this time, the diaphragm 11 and the fixed electrode 2
The relationship of the capacitance Cs to 1 is expressed by the following equation.

Cs = ε (A / d)

Here, ε: dielectric constant of air, A: electrode area, d: gap between electrodes.

That is, the capacitance changes due to the change in the gap. Further, there is a certain correlation between the pressure and the gap, and the detected pressure can be measured from the change in the capacitance.

[0013]

In the conventional capacitance type pressure sensor, the patterning of the insulating film 25 and the conductor film 24 on the glass substrate 20 is formed by etching.
In addition, when the insulating film 25 and the conductor film 24 are formed by etching, in order to prevent the glass substrate 20 from being damaged by the etching solution, it is necessary to provide a protective film 50 in a region outside the pattern of each film and to proceed with the process. Was. Further, since the fixed electrode, the insulating film, and the conductor film are formed in the cavity 12, the thickness of each film is limited. In particular, the insulating film that insulates the fixed electrode lead-out pattern from the conductive film needs to have a thickness that is two to three times the thickness of the fixed electrode lead-out pattern. There was a disadvantage that there was a risk of short-circuiting.

Accordingly, a technical problem of the present invention is to eliminate the above drawbacks by forming an insulating film on the entire surface of the region other than the pad portion of the fixed electrode lead-out pattern and insulating the movable electrode pad portion. An object of the present invention is to provide a capacitance type pressure sensor which has a short manufacturing process and a high yield by being formed on a film and bonding a silicon substrate and an insulating film substrate via an insulating film.

[0015]

According to the present invention, in order to attain the above object, an insulating film on a glass substrate is formed in an entire region except for a fixed electrode lead pattern pad portion, and a glass substrate and a silicon substrate are formed on the insulating film. It is designed to be joined via a wire.

That is, according to the present invention, the movable electrode deformed by the pressure on the silicon substrate and the fixed electrode on the insulating substrate are opposed to each other with a gap formed therebetween, and the silicon substrate and a part of the insulating substrate are joined. Forming a cavity portion, taking out the movable electrode outside the cavity portion by a movable electrode pad provided on the insulating substrate via the silicon substrate, and forming the fixed electrode on the insulating substrate. The fixed electrode lead-out pattern is taken out of the cavity portion, and a conductive film is provided on the fixed electrode lead-out pattern and between the fixed electrode lead-out pattern and the movable electrode pad through the periphery of the fixed electrode, an insulating film. In the capacitive pressure sensor configured as described above, the fixed electrode excluding the pad portion of the fixed electrode lead pattern, the insulating film, A capacitive pressure sensor, characterized in that formed on the insulating substrate entire surface of the fine fixed electrode lead pattern is formed.

According to the present invention, in the above-mentioned capacitive pressure sensor, the movable electrode pad is formed on the insulating film on the insulating substrate, and the silicon substrate and the insulating substrate are interposed via the insulating film. This is a capacitance type pressure sensor characterized by joining.

According to the present invention, the insulating film on the glass substrate is formed in the entire region except for the fixed electrode lead pattern pad portion, and the glass substrate and the silicon substrate are joined via the insulating film, whereby the insulating film is patterned. Before forming a protective film to protect the glass substrate,
There is no need to pattern the insulating film. Further, since there is no limit on the thickness of the insulating film, the thickness required for insulating the fixed electrode lead pattern and the conductive film can be sufficiently formed, and the yield is improved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A capacitance type pressure sensor according to an embodiment of the present invention will be described below with reference to the drawings.

The configuration of the capacitance type pressure sensor according to the embodiment of the present invention is almost the same as that of the conventional technology described with reference to FIG. 3, so that the detailed description is omitted, and only the differences are shown in FIGS. This will be described in more detail in 2.

FIG. 1 is a view showing the structure of a sensor chip of a capacitance type pressure sensor according to an embodiment of the present invention.
1 (a) is an exploded perspective view thereof, and FIG. 1 (b), FIG.
(C) and FIG. 1 (d) respectively show AA and B in FIG. 1 (a).
It is sectional drawing of -B and CC. As shown in FIG. 1, a fixed electrode 21, a fixed electrode lead pattern 22, and a fixed electrode lead pattern pad 26 are arranged on a glass substrate 20. Further, the insulating film 25 is formed in all regions except the fixed electrode lead pattern pad portion 26. On the insulating film 25, in addition to the movable electrode pad portion 23, the peripheral portion of the fixed electrode 21, the fixed electrode lead pattern portion 22
A conductor film 24 is disposed above and between the fixed electrode lead pattern portion 22 and the movable electrode pad portion 23. Therefore, the fixed electrode 21 has a structure in which the entire surface is covered with the insulating film 25, and the dew condensation on the surface of the fixed electrode 21 due to the intrusion of impurities such as humidity and dust in the air into the cavity portion 12, and the fixed electrode 21 In addition to the conventional feature that a short circuit can be prevented, the thickness of the insulating film can be arbitrarily set without being limited by the height of the cavity. It is possible to obtain a sufficient film thickness necessary to secure the thickness.

FIG. 2A is a view showing a portion A of FIG. 1A shown in FIG.
3A shows a step of forming an insulating film and a conductor film with respect to the A section. After the insulating film 25 is formed by sputtering or CVD on the entire surface of the glass substrate 20 on which the fixed electrode 21, the fixed electrode leading pattern 22, and the fixed electrode leading pattern pad portion 26 are formed, the conductor film 24 is further covered with the whole surface. To form a film [FIG. 2 (a)]. Next, the conductive film 24 and the movable electrode pad portion 2 are formed using a photoresist.
After that, a resist pattern of No. 3 is formed, and thereafter, a pattern of the conductor film 24 and the movable electrode pad portion 23 are formed by an etching method (FIG. 2B). Next, using the resist pattern, only the insulating film of the fixed electrode lead pattern pad portion 26 is removed by etching [FIG. 2 (c)].

By using the above-described steps, the insulating film 2
By forming the conductive film 5 and the conductor film 24, the patterning of the protective film in the conventional process and the removal process thereof can be reduced.

[0024]

As described above, according to the present invention, an insulating film is disposed on the entire surface of a glass substrate on which each fixed electrode pattern is disposed except for a fixed electrode lead pattern pad portion, and the glass substrate and the silicon By bonding the substrates via the insulating film, it is not necessary to form a protective film on the glass substrate before patterning the insulating film. Further, since there is no limit on the thickness of the insulating film, the thickness required for insulating the fixed electrode lead pattern and the conductive film can be sufficiently formed, and the yield is improved. That is, it is possible to manufacture a capacitance-type pressure sensor with a smaller number of manufacturing steps and a higher yield than before.

[Brief description of the drawings]

FIG. 1 is a diagram showing a sensor chip of a capacitance type pressure sensor according to an embodiment of the present invention, FIG. 1 (a) is a perspective view showing a structure, FIGS. 1 (b), 1 (c), 1 FIG.
Sectional drawing of each AA, BB, and CC of (a).

FIG. 2 is a diagram showing a manufacturing process of an insulating film and a conductive film on the glass substrate side of the sensor chip of the capacitance type pressure sensor according to the embodiment of the present invention along the line AA in FIG. −
A section).

FIG. 3 is an explanatory view of a conventional capacitance type pressure sensor, FIG.
FIG. 3A is a perspective view with a cap removed, and FIG. 3B is a cross-sectional view.

FIG. 4 is a view showing a sensor chip of a conventional capacitance type pressure sensor, FIG. 4 (a) is a perspective view showing the sensor chip, and FIG.
4 (b) and FIG. 4 (c) show AA and BB in FIG. 4 (a).
FIG.

FIG. 5 shows a conventional capacitance type pressure sensor chip.
FIG. 3A is a diagram illustrating a manufacturing process of an insulating film and a conductive film on the glass substrate side with respect to the AA cross section of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Silicon substrate 11 Diaphragm part (movable electrode) 12 Cavity part 13 Horizontal hole for fixed electrode lead-out 20 Glass substrate 21 Fixed electrode 22 Fixed electrode lead-out pattern 23 Movable electrode pad 24 Conductive film 25 Insulating film 26 Fixed electrode lead-out pattern pad part 30 Sensor Chip 31 Atmospheric pressure introduction hole 32 Sealant 33, 34, 35 Lead wire 40 Pedestal 41 Cap 42 Measured pressure introduction hole 43 Atmospheric pressure introduction hole 44, 45, 46 Lead terminal 47 Inner cap area 50 Protective film (glass substrate) 51 Photoresist (for conductor film heater (for etching)) 52 Photoresist (for insulator film heater (for etching))

Claims (2)

[Claims] A movable electrode deformed by pressure on a silicon substrate and a fixed electrode on an insulating substrate are opposed to each other by forming a gap, and a part of the silicon substrate and the insulating substrate are joined to form a cavity portion. Is formed, and the movable electrode is taken out of the cavity portion by a movable electrode pad provided on the insulating substrate via the silicon substrate, and the fixed electrode is led out to a fixed electrode formed on the insulating substrate. A static film formed by taking out a pattern outside the cavity portion and providing a conductive film on the fixed electrode lead pattern and between the fixed electrode lead pattern and the movable electrode pad via the periphery of the fixed electrode and an insulating film. In the capacitance type pressure sensor, the insulating film may be formed by removing the fixed electrode except for a pad portion of the fixed electrode lead pattern, and the fixed electrode lead. A capacitance-type pressure sensor formed on the entire surface of the insulating substrate on which a projection pattern is formed. 2. The capacitance type pressure sensor according to claim 1, wherein the movable electrode pad is formed on the insulating film on the insulating substrate, and connects the silicon substrate and the insulating substrate to the insulating film. A capacitance-type pressure sensor, wherein the pressure sensor is joined through a wire.