JPH09304210A - Capacitance-type pressure sensor and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sensor without burrs by forming insulation films on a fixed electrode and between a fixed electrode draw-out pattern and a conductor film, and providing for protection a protection film in a region outside a pattern when patterning of the insulation film on a glass substrate and the conductor film is formed by etching. SOLUTION: A protection film 50 for protecting a glass substrate 20 is patterned on a region outside the pattern on the glass substrate formed with a fixed electrode or a fixed electrode draw-out pattern 22. Then an insulation film 25 and a conductor film 24 thereon are formed on an entire face by sputtering. Next photoresist 51 is used to form a resist pattern of the conductor film 24, and then a pattern of the conductor film 24 is formed by etching. Next a resist pattern 52 of the insulation film 25 is formed in a method similar to formation of the conductor film 24 to form a pattern of the insulation film 25. Finally the protection film 50 is removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic capacitance type pressure sensor in which electrodes are formed on a silicon substrate and an insulating substrate, and the respective electrode surfaces are opposed to each other with a predetermined gap therebetween and bonded to each other. And a method for manufacturing the same.

[0002]

2. Description of the Related Art As this type 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. Also, FIG.
Is a sensor chip 3 of the capacitance type pressure sensor shown in FIG.
FIG. 4A is a developed view, and FIGS. 4B and 4C are views showing the structure of the 0 part, and FIGS. 4B and 4C are respectively AA and B of FIG. 4A.
It is a sectional view of -B.

The structure of a conventional capacitance type pressure sensor is shown in FIG.
And FIG. A diaphragm portion 11 that functions as a movable electrode that deforms in response to pressure is formed on the silicon substrate 10, and a fixed electrode 21 is formed on a glass substrate 20 that is an insulating substrate. Silicon substrate 10
The glass substrate 20 and the glass substrate 20 are joined at a part thereof, whereby the cavity portion 12 is formed below the diaphragm portion 11.

The sensor chip 30 composed of the silicon substrate 10 and the glass substrate 20 has a fixed hole 13
Is provided, whereby the fixed electrode 21 is drawn out of the cavity portion 12 through the fixed electrode drawing pattern 22. The diaphragm portion 11, which is a movable electrode,
It is pressed through the silicon substrate 10 to the movable electrode pad 23 provided on the glass substrate 29 and taken out of the cavity portion 12.

Furthermore, the parasitic capacitance that changes due to the detected pressure that wraps around the peripheral portion of the diaphragm 11 and fixed electrode 21 that function as movable electrodes, and the parasitic capacitance that does not change due to the detected pressure generated by the fixed electrode lead-out pattern 22 and the like. 4 (a) as a guard for suppressing
As shown in FIG. 6, the peripheral portion of the fixed electrode 21, the fixed electrode lead-out pattern 22 and the fixed electrode lead-out pattern 22
The conductive film 24 is provided between the movable electrode pad 23 and the movable electrode pad 23. In addition, as shown in FIG. 4B, an insulating film 25 for electrically isolating the fixed electrode lead pattern 22 and the conductor film 24 is provided between the fixed electrode lead pattern 22 and the conductor film 24. There is.

Here, a conventional method of manufacturing the insulating film 25 and the conductor film 24 will be described with reference to the process diagram shown in the sectional view of FIG. A pattern of the insulating film 25 is formed by the photoresist 60 on the glass substrate 20 on which the fixed electrode 21 is formed [FIG. 5 (a)]. Then, the insulating film 25 is formed by sputtering.
Is formed [FIG. 5B], and the insulating film 2 is formed by the lift-off method.
5 pattern is formed [FIG. 5 (c)]. Next, a pattern of the conductor film 24 is formed by the resist 61 [FIG.
(D)] After that, the conductor film 24 is formed by sputtering [FIG. 5 (e)], and the pattern of the conductor film 24 is formed by the lift-off method [FIG. 5 (f)].

By the above method, the conductor film 24 and the insulating film 2 are formed.
5, the sensor chip 30 is formed as shown in FIG.
Is adhered onto a pedestal 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 21 (via the fixed electrode pad 22) on the glass substrate 20, the movable electrode pad 23, and The conductor film 24 is the lead wire 3
They are electrically connected by 3, 34 and 35.

Through holes 31 and 43 for introducing atmospheric pressure are formed in the glass substrate 20 and the pedestal 40, respectively.
These two atmospheric pressure introducing holes 31 and 43 communicate with each other.
In order to isolate the cavity portion 12 and the cap inner region 47 outside the sensor chip, the lateral hole 13 for drawing out the fixed electrode is formed.
Are sealed by the sealant 32. Then, the pedestal 40 and the cap 41 as a cover member having the through hole 42 for introducing the measured pressure are sealed by a hermetic seal, and the sensor is completed.

The structure of the capacitance type pressure sensor has been described above, but the operation principle will be described below. When pressure is applied to the diaphragm portion 11 which also serves as the movable electrode, the diaphragm portion 11 is deformed, and the gap between the diaphragm portion 11 and the fixed electrode 21 facing the diaphragm portion 11 changes, so that the static pressure between the diaphragm portion 11 and the fixed electrode 21 changes. The relationship when the capacitance is Cs is expressed by the following equation.

Cs = εA / 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, since there is a certain correlation between the pressure and the gap, the pressure to be detected can be measured from the change in capacitance.

[0013]

Since the pattern formation of the insulating film 25 and the conductor film 24 on the glass substrate 20 in the conventional capacitance type pressure sensor is performed by the lift-off method as described above, the insulating film 25 and the conductor are formed. Burrs [see FIG. 5 (f)] may be formed on the pattern edge portion of the film 24, and when the glass substrate 20 and the silicon substrate 10 are bonded to form a gap, the burr on the pattern edge portion is formed. When the diaphragm portion 11 of the silicon substrate 10 is contacted and the pressure to be measured is applied to the capacitance type pressure sensor, the deformation of the diaphragm portion 11 is hindered and the output characteristic of the sensor is abnormal. In addition, there is an inconvenience that conductive foreign matter such as moisture and dust intrudes into the cavity portion 12 to cause dew condensation on the surface of the fixed electrode 21 and the intruding conductive foreign matter causes a short circuit between the electrodes.

In order to eliminate the above-mentioned drawbacks, a technical object of the present invention is to dispose an insulator between the fixed electrode and the movable electrode,
By eliminating a short circuit between electrodes due to conductive foreign matter or dew condensation, and by using a process that does not cause burrs at the pattern edge portion of each film at the stage of forming an insulating film and a conductor film, the fixed electrode An object of the present invention is to provide a capacitance type pressure sensor having good output characteristics by eliminating a short circuit accident due to dew condensation on the surface.

[0015]

In order to achieve the above-mentioned object, the present invention forms an insulating film on a fixed electrode and between a fixed electrode extraction pattern and a conductor film, and The patterning of the conductor film is formed by etching. Further, when forming each film by etching, in order to prevent the glass substrate from being damaged by the etching solution, a protective film is provided in an out-of-pattern region of each film, and the process proceeds.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION By providing a protective film on a region outside a pattern on a glass substrate and forming a pattern of an insulating film and a conductor film by etching, the insulating film and the insulating film can be formed without damaging the glass substrate. A burr-free pattern can be produced at the edge portion of the conductor film pattern. By doing so, there is nothing that hinders the deformation of the diaphragm portion formed on the silicon substrate due to the detected pressure, so that the diaphragm portion can be smoothly deformed, and good output characteristics can be obtained.

Hereinafter, the constitution of the present invention will be specifically described by way of examples.

(Embodiment) The description of the structure of the capacitance type pressure sensor of the present invention is omitted about the same parts as the prior art described with reference to FIG. 3, and the sensor which is the point of the present invention. Only the tip portion will be described in detail.

FIG. 1 is a view showing the structure of a sensor chip of the capacitance type pressure sensor of the present invention, FIG. 1 (a) is a development view, and FIG. 1 (b) and FIG. 1 (c). 2A and 2B are cross-sectional views taken along lines AA and BB of FIG. As shown in FIG.
Peripheral part of fixed electrode 21, fixed electrode lead-out pattern 22
A conductor film 24 is provided on the top and between the fixed electrode lead-out pattern 22 and the movable electrode pad 23. Insulating film 2
5 electrically isolates the fixed electrode lead-out pattern 22 and the conductor film 24 from each other, so that the fixed electrode 2 is provided between the fixed electrode lead-out pattern 22 and the conductor film 24 [see FIG. 1 (b)].
1 and on the entire lower surface of the conductor film 24 [see FIG. 1 (c)]. Therefore, the fixed electrode 21 has a structure covered by the entire surface insulating film 25, and when impurities such as moisture and dust in the atmosphere enter the cavity portion 12, dew condensation occurs on the surface of the fixed electrode 21 and between the electrodes. It is possible to prevent a short circuit.

FIG. 2 shows a process of manufacturing an insulating film and a conductor film on a glass substrate. A protective film 50 for protecting the glass substrate 20 is patterned in an area outside the pattern on the glass substrate 20 on which the fixed electrode 21 or the fixed electrode lead-out pattern 22 is formed [FIG. 2 (a)]. Next, the insulating film 25 and the conductor film 24 are formed on the entire surface by sputtering [FIG. 2 (b)]. Next, a resist pattern of the conductor film 24 is formed using the photoresist 51, and then a conductor film pattern is formed by an etching method [FIG. 2 (c)]. Next, the resist pattern 52 of the insulating film 25 is formed by the same method as that for forming the conductor film 24,
A pattern of the insulating film 25 is formed [FIG. 2 (d)]. Finally, the protective film 50 is removed [FIG. 2 (e)].

By forming the insulating film 25 and the conductor film 24 by using the steps described above, the pattern edge portion of each film of the insulating film 25 and the conductor film 24 can be formed without damaging the glass substrate 20. A burr-free film can be formed.

[0022]

As described above, according to the present invention,
By forming the protective film on the glass substrate and then forming the insulating film and the conductor film by the etching method, burrs do not occur at the pattern edge portions of the insulating film and the conductor film. That is, since it is possible to eliminate the obstacle that prevents the deformation of the diaphragm when the pressure of the sensor chip is applied, it is possible to obtain good output characteristics. Further, by adopting a structure in which the fixed electrode is covered with an insulating film, a capacitance type pressure sensor having good environment resistance can be manufactured.

[Brief description of drawings]

1 is a diagram showing a sensor chip of an electrostatic capacity type pressure sensor of the present invention, FIG. 1 (a) is a perspective view showing the structure, FIG.
(B) and FIG. 1 (c) are AA and BB of FIG. 1 (a).
FIG.

FIG. 2 is a diagram showing a process of manufacturing an insulating film and a conductor film on the glass substrate side of the capacitance type pressure sensor chip of the present invention.

3A and 3B are diagrams showing an outline of the structure of a conventional capacitance type pressure sensor, FIG. 3A is a perspective view with a cap removed, and FIG. 3B is a sectional view.

FIG. 4 shows a sensor chip of a conventional electrostatic capacitance type pressure sensor, and FIG. 4 (a) is a perspective view showing the sensor chip.
4B and FIG. 4C show A-A and B- in FIG. 4A.
Sectional drawing of B.

FIG. 5 is a diagram showing a manufacturing process of an insulating film and a conductive film on a glass substrate side of a conventional capacitive pressure sensor chip.

[Explanation of symbols]

10 Silicon Substrate 11 Diaphragm Part (Movable Electrode) 12 Cavity Part 13 Horizontal Hole for Extracting Fixed Electrode 20 Glass Substrate 21 Fixed Electrode 22 Fixed Electrode Extraction Pattern 23 Movable Electrode Pad 24 Conductive Film 25 Insulating Film 30 Sensor Chip 31 Penetration for Atmospheric Pressure Introduction Hole 32 Sealant 33, 34, 35 Lead wire 40 Pedestal 41 Cap 42 Through hole for introducing pressure to be measured 43 Through hole for introducing atmospheric pressure 44, 45, 46 Lead terminal 47 Cap area 50 Protective film 51 Photoresist (conductor) Film patterning [for etching] 52 Photoresist (for insulating film patterning [etching] 60 Photoresist (for insulating film patterning [lift-off] 61 Photoresist (for conductor film patterning [lift-off])

Claims (2)

[Claims] 1. A movable electrode deformable by pressure on a silicon substrate and a fixed electrode on an insulating substrate are opposed to each other to form a gap, and the silicon substrate and a part of the insulating substrate are bonded to each other to form a cavity portion. Formed, the movable electrode is taken out of the cavity through the silicon substrate by the movable electrode pad provided on the insulating substrate, and the fixed electrode is a fixed electrode lead pattern formed on the insulating substrate. To the outside of the cavity by a conductor film provided on the fixed electrode lead pattern through the peripheral portion of the fixed electrode and an insulating film and between the fixed electrode lead pattern and the movable electrode pad. In the capacitance type pressure sensor, an insulating film is formed on the fixed electrode and between the fixed electrode lead-out pattern and the conductor film. Characteristic capacitance type pressure sensor. 2. A method of manufacturing a capacitance type pressure sensor, characterized in that, when the conductor film and the insulating film according to claim 1 are formed, a protective film is provided in an area outside the pattern of each film and is formed by etching. Method.