JP2001194254A - Capacitance type pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a capacitance type pressure sensor in which the defective insulation between a fixed electrode leading-out pattern and a conductive film is eliminated and a parasitic capacitance suppressing effect is improved. SOLUTION: The capacitance type pressure sensor is formed by bonding a silicon substrate 10 on which a movable electrode 11 is formed to a glass substrate 20 on which a fixed electrode is formed. The movable electrode 11 is electrically connected to a movable electrode pad 23 provided on the glass substrate 20 and the fixed electrode 21 is electrically connected to the fixed electrode leading-out pattern 22 formed on the substrate 20. The glass substrate 20 is constituted in such a way that a conductive film 24 is provided on the whole surface of the substrate 20 and an insulating film 25 is provided on the whole surface of the conductive film 24. In addition, the fixed electrode 21, the leading-out pattern 22, and electrode pad 26 are formed on the insulating film 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of joining a silicon substrate having movable electrodes and an insulating substrate having fixed electrodes, which are used for various industrial equipment and home electric appliances, with their respective electrode surfaces facing each other. To a capacitance type pressure sensor.

[0002]

2. Description of the Related Art As a conventional capacitance type pressure sensor, a capacitance type pressure sensor shown in FIG. 2 is generally known. FIG. 2A is an external perspective view showing the interior with the cap removed, and FIG. 2B is a cross-sectional view.
FIG. 3 is a view showing the structure of a sensor chip 30 'of the capacitance type pressure sensor shown in FIG. 2, FIG. 3 (a) is a development view, and FIG. 3) is a cross-sectional view taken along line AA, and FIG. 3C is a cross-sectional view taken along line BB in FIG.

The structure of a conventional capacitance type pressure sensor will be described with reference to FIGS. Silicon substrate 10 '
Is formed with a diaphragm portion 11 'functioning as a movable electrode deformed in response to pressure, and a fixed electrode 21' is formed on a glass substrate 20 '. As shown in the figure, the silicon substrate 10 'and the glass substrate 20' are joined at a part thereof, whereby the diaphragm 1
A cavity 12 '(see FIG. 2B) is formed below 1'.

The sensor chip 30 'composed of the silicon substrate 10' and the glass substrate 20 'is provided with a fixed electrode lead-out lateral hole 13', whereby the fixed electrode 21 'is passed through the fixed electrode lead-out pattern 22' to the cavity portion 1 '.
Pulled out of 2 '.

[0005] The movable electrode, which is the diaphragm portion 11 ',
The cavity 1 is pressed through the silicon substrate 10 ′ and pressed against the fixed electrode pad 23 ′ provided on the glass substrate 20 ′.
It is taken out of 2.

Further, a parasitic capacitance which varies depending on a detected pressure which flows from the periphery of the diaphragm portion 11 'functioning as a movable electrode and the fixed electrode 21', and the fixed electrode 2
As a guard for suppressing a parasitic capacitance which does not change due to the detected pressure generated by the extraction pattern 22 'of 1' and the like, as shown in FIG. A conductor film 24 'is disposed above and between the movable electrode pads 23'.
As shown in FIG. 3B, the fixed electrode lead-out pattern 2
An insulating film 25 'is arranged between 2' and the conductive film 24 'to electrically isolate the fixed electrode lead-out pattern 22' from the conductive film 24 '.

Here, a method of forming the insulating film 25 'and the conductor film 24' will be described with reference to the process chart shown in the sectional view of FIG. A pattern of the insulating film 25 'is formed by a photoresist 60 on the glass substrate 20' on which the fixed electrode 21 'is formed [FIG. 4 (a)]. Thereafter, an insulating film 25 'is formed by sputtering [FIG. 4B], and a pattern of the insulating film 25' is formed by a lift-off method [FIG.
(C)].

Next, a resist 61 is used to form the conductive film 2.
4 (a), a conductor film 24 'is formed by sputtering [FIG. 4 (e)], and a pattern of the conductor film 24' is formed by a lift-off method [FIG. 4 (f)].

The sensor chips 30 'are 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 fixed electrode pad 23 ′, and the conductor film 2
4 'is electrically connected to each terminal by lead wires 33, 34, 35.

[0010] Atmospheric pressure introduction through holes 31 and 43 are formed in the glass substrate 20 'and the pedestal 40, respectively, and these two atmospheric pressure introduction holes 31' and 43 are connected to each other.

The lateral hole 13 ′ is sealed by a sealant 32 in order to isolate the cavity 12 ′ from the cap inner region 47 outside the sensor chip. 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.

[0012]

The conventional capacitance type pressure sensor has the following problems. That is, the method of forming the pattern of the insulating film 25 'and the conductor film 24' on the glass substrate 20 'side in the capacitance type pressure sensor requires two photolithography steps and a complicated manufacturing step, This requires a large number of man-hours, leading to an increase in cost.

Further, since a step is formed at the pattern edge portion of the insulating film 25 'and the conductor film 24', the insulating film 2 '
The conductor film 24 'and the fixed electrode lead-out pattern 2 due to insufficient cover of the 5' fixed electrode lead-out pattern 22 '
There was a defect that insulation failure occurred between 2 'and output characteristics of the sensor were abnormal.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a reliable electrostatic capacitance type pressure sensor which eliminates defective insulation between a fixed electrode lead-out pattern and a conductive film and has an improved effect of suppressing a parasitic capacitance. is there.

[0015]

According to the present invention, in order to achieve the above object, a conductive film is formed on the entire surface of a glass substrate, and the conductive film is formed on the entire surface other than the pad portion for taking out the conductive film to the outside.
After forming an insulating film, a fixed electrode (fixed electrode lead pattern) and a movable electrode pad are provided.

According to the present invention, the man-hour for forming the conductor film as a guard for suppressing the parasitic capacitance can be greatly reduced, and since there is no step in the pattern as in the prior art, the insulation failure accident can be eliminated. Since the film is provided on the entire surface of the substrate, the effect of suppressing the parasitic capacitance increases, so that it is possible to obtain a high-reliability and high-productivity capacitive pressure sensor with good output characteristics.

That is, the present invention relates to a capacitance type pressure sensor formed by joining a silicon substrate on which a movable electrode is formed and an insulating substrate on which a fixed electrode is formed, wherein the movable electrode comprises an insulating substrate The fixed electrode is electrically connected to a movable electrode pad provided thereon, the fixed electrode is electrically connected to a fixed electrode lead pattern on an insulating substrate, and the insulating substrate is a glass substrate. A conductive film is provided on the entire surface of the conductive film, and then on the conductive film, has a multilayer film provided with an insulating film on the entire surface, on the insulating film,
This is a capacitance type pressure sensor in which a fixed electrode, a fixed electrode lead pattern and a movable electrode pad are formed.

According to the present invention, in the capacitance type pressure sensor, at least a part of a region of the conductor film on the insulating substrate is exposed by a hollow portion in the insulating film. Is a capacitance type pressure sensor using a conductor film pad.

[0019]

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

FIG. 1 is a view showing the structure of a sensor chip of a capacitance type pressure sensor according to the present invention. FIG. 1 (a) is a developed view, and FIG. 1 (b) is FIG. 1 (a). 1A is a cross-sectional view of FIG. 1C, and FIG. 1C is a cross-sectional view of BB of FIG.

As shown in FIG. 1A, the glass substrate 2
0, a conductive film 24 is provided on the entire surface. On the conductive film 24, a portion except for a conductive film pad portion 26 for extracting the potential of the conductive film 24 to the outside is provided with a uniform thickness. An insulating film 25 is provided.

Therefore, since no step is formed between the conductor film 24 and the insulating film 25, the insulation between the fixed electrode 21 (fixed electrode lead pattern 22) and the movable electrode pad 23 via the conductor film 24 and the insulating film 25 is formed. Bad accidents can be eliminated. Further, since the conductive film 24 is formed on the entire surface of the glass substrate 20, there is an effect of suppressing the parasitic capacitance of the entire sensor chip 30.

The conductor film pad 26 is formed by a lift-off method or an etching method, and is connected to the ground when used as a pressure sensor.

In this manner, the conductor film 24 has the potential of the ground, so that the parasitic capacitance in the sensor chip can be suppressed. In addition, since the conductor film forming step can be manufactured by one photolithography step, the number of manufacturing steps can be significantly reduced as compared with the conventional manufacturing step.

As described above, according to the present invention, it is possible to obtain an inexpensive capacitive pressure sensor having good output characteristics, high reliability, high productivity, and high productivity by increasing the effect of suppressing the parasitic capacitance. it can.

[0026]

As described above, according to the present invention, it is possible to provide a reliable capacitance type pressure sensor which eliminates insulation failure between the fixed electrode lead-out pattern and the conductor film and improves the effect of suppressing the parasitic capacitance. Can be.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a sensor chip of a capacitance type pressure sensor according to an embodiment of the present invention. 1A is a perspective view showing a sensor chip, FIG. 1B is a sectional view taken along the line AA in FIG. 1A, and FIG. 1C is a sectional view taken along the line B-A in FIG. B sectional drawing.

FIG. 2 is an explanatory view of a conventional capacitance type pressure sensor. FIG.
(A) is an external perspective view with the cap removed, FIG. 2 (b)
Is a sectional view.

FIG. 3 is an explanatory view of a sensor chip of a conventional capacitance type pressure sensor. FIG. 3A is a perspective view showing a conventional capacitance-type pressure sensor chip, and FIG. 3B is a sectional view taken along line AA in FIG.
FIG. 3C is a sectional view, and FIG. 3C is a sectional view taken along line BB in FIG.

FIG. 4 is a view showing a process for forming an insulating film and a conductive film on the glass substrate side of a conventional capacitance-type pressure sensor chip. FIG.
FIG. 4A shows a state in which a pattern of the insulating film is formed by a photoresist on a glass substrate on which a fixed electrode is formed. FIG. 4B shows a state in which the insulating film is formed by sputtering thereafter. FIG. 4C is a view showing a state in which the pattern of the insulating film is formed by a lift-off method, and FIG. 4D is a view showing a state in which the pattern of the conductor film is formed by a resist. 4 (e) is then
FIG. 4 shows a state in which a conductive film is formed by sputtering.
(F) is a diagram showing a state in which the pattern of the conductor film is formed by a lift-off method.

[Explanation of symbols]

 10, 10 'Silicon substrate 11, 11' Diaphragm part (movable electrode) 12, 12 'Cavity part 13, 13' Horizontal hole for extracting fixed electrode 20, 20 'Glass substrate 21, 21' Fixed electrode 22, 22 'Fixed electrode Leader pattern 23,23 'Movable electrode pad 24,24' Conductor film 25,25 'Insulating film 26,26' Conductor film pad 30,30 'Sensor chip 31,31 Atmospheric pressure introduction hole 32 Sealant 33,34,35 Lead wire 40 Pedestal 41 Cap 42 Pressure introduction hole to be measured 43 Atmospheric pressure introduction hole 44, 45, 46 Lead terminal 60, 61 Photoresist

Claims (2)

[Claims] 1. A capacitive pressure sensor formed by joining a silicon substrate on which a movable electrode is formed and an insulating substrate on which a fixed electrode is formed, wherein the movable electrode is provided on the insulating substrate. The fixed electrode is electrically connected to a movable electrode pad, and the fixed electrode is electrically connected to a fixed electrode lead pattern on an insulating substrate. A structure in which a film is provided, and then, on the conductor film, a multilayer film having an insulating film provided on the entire surface, and on the insulating film, a fixed electrode, a fixed electrode lead pattern and a movable electrode pad are formed. Characteristic capacitance type pressure sensor. 2. The capacitive pressure sensor according to claim 1, wherein at least a part of a region of the conductive film on the insulating substrate is exposed by a hollow portion in the insulating film.
The exposed area is a conductive film pad.