JP2000214035A - Electrical capacitance pressure sensor and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the temperature dependency of the zero point and sensitivity of the electrical capacitance pressure sensor using a movable diaphragm formed of a thin film. SOLUTION: On the main surface of a single-crystal silicon substrate 50, a pressure-sensitive capacity part 500 which varies in capacitance by pressure application and a reference capacity part 600 which does not vary are provided are the movable diaphragm 300 is formed of 1st and 2nd insulating diaphragm films 100 and 130, a 1st upper electrode 110, and a heat-stress reducing film 200 (silicon nitride film by, e.g. plasma CVD) using a material having a coefficient of thermal expansion close to that of the single-crystal silicon substrate. Consequently, the mean coefficient of thermal expansion of the movable diaphragm 300 is approximated to that of the substrate and thermal stress decreases. Further, the capacity difference between the two capacitors of the pressure-sensitive capacity part 500 and reference capacity part 600 which are close to each other is detected to cancel the effect of temperature.

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 particular, a capacitance formed by forming a diaphragm on the surface of a silicon substrate by using a silicon micromachining technology combining a semiconductor processing technology and a desired etching technology. The present invention relates to a mold pressure sensor and a method for manufacturing the same.

[0002]

2. Description of the Related Art FIG. 15 shows a sectional structure of a conventional capacitance type pressure sensor in which a thin film diaphragm is formed on a surface of a semiconductor substrate.

The capacitance type pressure sensor comprises a lower electrode 11 and a lower electrode 1 formed on a main surface of a silicon substrate 10.
1, a pressure reference chamber 30, a movable diaphragm 4
0, and a sealing cap 16 for maintaining the pressure reference chamber 30 at a desired pressure state. The movable diaphragm 40 is formed so as to cover the pressure reference chamber 30 and includes a first insulating diaphragm film 13, an upper electrode 14, and a second insulating diaphragm film 15.

In this sensor, when a pressure P is applied from a direction indicated by an arrow in the figure, the movable diaphragm 40 is deformed in response thereto. Due to this deformation, the gap between the upper electrode 14 and the lower electrode 11 constituting the movable diaphragm 40 changes, and the capacitance of the capacitor formed by the upper electrode 14 and the lower electrode 11 changes. Then, the pressure P is detected by detecting the capacitance.

Here, an n-type single-crystal silicon substrate is used for the silicon substrate 10, and the lower electrode 11 is doped and diffused so that boron is ion-implanted into the main surface of the silicon substrate 10 as an impurity to contain a high concentration. It is formed using the p-type semiconductor obtained as described above. Lower electrode 11 and pressure reference chamber 3
Between 0 and 0, a sacrificial film 12 using polycrystalline silicon is formed in advance by low-pressure CVD. Upper electrode 14
Is formed by ion-implanting boron as an impurity into polycrystalline silicon formed by low-pressure CVD and treating it to contain a high concentration of boron to obtain high conductivity characteristics. Further, the first and second insulating diaphragm films 13 and 1 formed to cover the upper and lower portions of the upper electrode 14 are formed.
Reference numeral 5 uses a silicon nitride film formed by low-pressure CVD.

The pressure reference chamber 30 is formed with an etching solution injection port 20 so as to penetrate the second insulating diaphragm film 15 and the first insulating diaphragm film 13 and reach the sacrificial film 12. It is formed by etching and removing the sacrificial film 12 through the entrance 20. The sealing cap 16 uses a silicon nitride film formed by plasma CVD, and seals the etching solution inlet 20 so as to keep the pressure reference chamber 30 at a desired pressure state.

An etching solution such as an aqueous solution of potassium hydroxide or an aqueous solution of tetramethylammonium hydroxide is generally used to remove the sacrificial film 12 by etching. In this etching, the first and second insulating diaphragm films 13 and 15 have resistance to an etchant, can protect the upper electrode 14 from being etched (a dense material), and have a sacrificial film. It is desired that 12 can be held flat after etching removal (the internal stress is tensile). In order to satisfy this condition, a silicon nitride film formed by low pressure CVD is used for the first and second insulating diaphragm films 13 and 15.

In such a capacitance type pressure sensor, the sensitivity can be increased by narrowing the gap between the opposing electrodes forming the capacitor. Further, since the temperature dependence of the dielectric constant is small in principle, the temperature dependence of the sensitivity is small.

[0009]

However, in this conventional capacitance type pressure sensor, the first and second insulating diaphragm films 13 and 15 are formed by using a silicon nitride film formed by low pressure CVD. The thermal expansion coefficients of these films are the same as those of the silicon substrate 1 made of single crystal silicon.
It is considerably smaller than 0. Therefore, when the ambient temperature of the sensor changes, the thermal stress changes due to the difference in the coefficient of thermal expansion, and the temperature characteristics of the zero point and the sensitivity of the sensor deteriorate. The movable diaphragm 40
Since the polycrystalline silicon film of the upper electrode 14 constituting the above is substantially equal to the thermal expansion coefficient of the silicon substrate 10, the influence of the zero point of the sensor and the sensitivity on the temperature characteristics is small.

For example, the gap between the lower electrode 11 and the first insulating diaphragm film 13 is 200 nm, and the thicknesses of the silicon nitride films forming the first and second insulating diaphragm films 13 and 15 are both 200 nm, upper electrode 1
The temperature coefficient of the zero point and the temperature coefficient of the sensitivity of the sensor in which the thickness of the polycrystalline silicon of No. 4 is 200 nm and the diameter of the movable diaphragm 40 is 100 μm are each -3000 ppm.
/ ° C, 1000 ppm / ° C.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a capacitance type pressure sensor having zero temperature and small temperature dependence of sensitivity.

[0012]

In order to solve the above-mentioned problems, the present invention relates to a capacitance type pressure sensor for detecting pressure by a change in capacitance of a pressure-sensitive capacitance portion formed on a substrate. A pressure-sensitive capacitance portion, a first lower electrode formed on a first surface of the substrate, a movable diaphragm formed above the first lower electrode with a predetermined gap from the electrode, A pressure reference chamber formed in a gap between the lower electrode and the movable diaphragm, wherein the movable diaphragm has a first insulating diaphragm film formed on the pressure reference chamber side, and a first insulating film. A first upper electrode formed on the diaphragm film so as to face the first lower electrode, and a second insulating diaphragm film formed on the first upper electrode; The second insulating diaphragm Characterized in that it comprises a thermal stress relieving layer formed of a material having a thermal expansion coefficient close to that of the substrate above.

This thermal stress relaxation film is made of a material having a coefficient of thermal expansion closer to that of the substrate than the first and second insulating diaphragm films, for example, and is formed by, for example, plasma CVD. Silicon nitride film can be used.

As described above, according to the present invention, the movable diaphragm of the pressure-sensitive capacitance portion is formed on the second insulating diaphragm film by coating the thermal stress relaxation film having a thermal expansion coefficient close to the coefficient of thermal expansion of the substrate. By adjusting the thickness ratio between the thermal stress relaxation film and the first and second insulating diaphragm films, it is easy to make the average thermal expansion coefficient of the movable diaphragm close to the thermal expansion coefficient of the substrate. Therefore, the thermal stress generated between the movable diaphragm and the substrate due to a change in ambient temperature can be reduced, and the temperature characteristics of the zero point and the sensitivity of the sensor can be prevented from deteriorating.

Another feature of the present invention is that a reference capacitance portion is formed on the same substrate in proximity to the pressure-sensitive capacitance portion having the above-described structure.

The reference capacitance portion includes, for example, a second lower electrode formed on the main surface of the substrate using the same material as the first lower electrode, and the second lower electrode formed on the first lower electrode. An insulating diaphragm film, a second upper electrode formed on the first insulating diaphragm film so as to face the second lower electrode and made of the same material as the first upper electrode; A second insulating diaphragm film formed so as to cover the second upper electrode, and a thermal stress relieving film formed on the second insulating diaphragm film.

Further, as another configuration of the reference capacitance section, a second lower electrode formed on the main surface of the substrate by the same material as the first lower electrode, and a second lower electrode provided on the second lower electrode are provided. Cavity, the first insulating diaphragm film formed on the main surface side of the substrate so as to cover the cavity, and the first insulating diaphragm so as to face the second lower electrode. A second upper electrode formed on the film and made of the same material as the first upper electrode, the second insulating diaphragm film formed so as to cover the second upper electrode, and the second upper electrode; A configuration including a thermal stress relaxation film formed on an insulating diaphragm film is applicable.

By disposing a reference capacitance part having a structure substantially equal to the pressure-sensitive capacitance part as described above near this pressure-sensitive capacitance part, and taking the capacitance difference between the pressure-sensitive capacitance part and the reference capacitance part, Second
It is possible to cancel the change in the sensor temperature characteristic caused by the temperature change of the dielectric constant of, for example, a silicon nitride film forming the insulating diaphragm film. Therefore, it can be realized with higher accuracy, and the deterioration of the temperature characteristics of the zero point and the sensitivity can be prevented.

Another feature of the present invention is that, in the above-described sensor, a sacrifice film covering a pressure receiving region on a main surface of the substrate;
At least one first etchant inlet formed to penetrate the second insulating diaphragm film and the first insulating diaphragm film and reach the sacrificial film;
A pressure reference chamber formed by etching and removing the sacrificial film through the first etching liquid injection port, wherein the etching liquid injection port is sealed by the thermal stress relaxation film.

Another feature of the present invention is that a first lower electrode, a pressure reference chamber, a pressure-sensitive capacitance section having first and second insulating diaphragm films and a first upper electrode, A lower capacitance electrode and a reference capacitance unit including the first and second insulating diaphragm films and the second upper electrode are formed on the same semiconductor substrate. Forming the first and second lower electrodes on a main surface of the substrate, and forming a sacrificial film so as to cover the pressure-sensitive capacitance portion forming region of the substrate;
Forming a first insulating diaphragm film on the main surface of the semiconductor substrate so as to cover the sacrificial film; and forming a first insulating diaphragm film on the first insulating diaphragm film at a position facing the first lower electrode. Forming a first upper electrode, and simultaneously forming a second upper electrode on the first insulating diaphragm film at a position facing the second lower electrode; and forming the first and second upper electrodes on the first insulating diaphragm film. Forming a second insulating diaphragm film so as to cover the electrodes; and at least one etching solution inlet so as to penetrate the second and first insulating diaphragm films and reach the sacrificial film. Forming a pressure reference chamber by etching and removing the sacrificial film through the etchant inlet in the pressure-sensitive capacitance portion forming region; and forming a pressure reference chamber on the second insulating diaphragm film. Characterized in that it comprises a step of forming a thermal stress relieving layer by using a material having a thermal expansion coefficient close to that of the substrate by plasma CVD, a.

In such a capacitance type pressure sensor, when the etching solution injection hole is sealed by using a thermal stress relaxation film, a special process for sealing alone is not required, and the pressure in the pressure reference chamber is reduced. The pressure state can be maintained, for example, in a vacuum state. Therefore, the absolute pressure can be detected.

Further, in the above-described capacitance type pressure sensor, the pressure state is maintained at a predetermined state, and when pressure is applied to the sensor, the pressure-sensitive capacitance portion is always moved according to the pressure. The diaphragm is deformed, and the distance between the first upper electrode and the first lower electrode changes. Then, the capacitance of the capacitor formed by the first upper electrode and the first lower electrode changes according to the change in the distance. Further, if a reference capacitance portion is provided in addition to the pressure-sensitive capacitance portion, the distance between the second upper electrode and the second lower electrode does not change even when pressure acts on the reference capacitance portion. Therefore, the capacitance of the capacitor formed by the second upper electrode and the second lower electrode does not change, and the difference in capacitance between the pressure-sensitive capacitance portion and the reference capacitance portion is used to obtain the influence of temperature. Etc. can be offset.

This capacitance difference can be easily converted to a voltage and detected by a switched capacitor circuit. Further, since the switched capacitor circuit can be easily formed by a normal semiconductor process, it can be easily formed on the same substrate as the above-described sensor of the present invention. Therefore, an integrated sensor can be formed.

Further, another feature of the present invention is that the pressure reference chamber is not sealed but is constituted by a pressure introduction chamber connected to a pressure introduction port formed through the substrate. .

Still another feature of the present invention is that a first pressure reference chamber connected to a first pressure inlet formed through the substrate, a first and a second insulating diaphragm film, and a first pressure reference chamber. A second pressure reference connected to a pressure-sensitive capacitance section having an upper electrode, a second lower electrode, and a second pressure inlet formed through the first and second insulating diaphragm films. A reference capacitance unit including a chamber and a second upper electrode;
Is a method for manufacturing a capacitance type pressure sensor formed on the same semiconductor substrate. In this method, a step of forming the first and second lower electrodes on a first surface of the substrate, and a step of forming a sacrificial film in a region where the pressure-sensitive capacitance section and the reference capacitance section are formed on the substrate Forming a first insulating diaphragm film on the first surface of the substrate so as to cover the sacrificial film; and opposing the first lower electrode on the first insulating diaphragm film. Forming a first upper electrode at a position, and simultaneously forming a second upper electrode at a position on the first insulating diaphragm film opposite to the second lower electrode; Forming a second insulating diaphragm film so as to cover the second upper electrode, and reaching the substrate from the second surface side of the substrate to the sacrificial film at the position where the first pressure reference chamber is formed. Forming the first pressure inlet as described above; The second pressure is applied so as to penetrate the second and first insulating diaphragm films disposed on the first surface side of the substrate and reach the sacrificial film at the position where the second pressure reference chamber is formed. Forming an inlet, and etching the sacrificial film at a position where the first and second pressure reference chambers are formed by using the first and second pressure inlets as an etchant inlet; And forming a second pressure reference chamber, and forming a thermal stress relaxation film on the second insulating diaphragm film using a material having a thermal expansion coefficient close to that of the substrate by plasma CVD. It is characterized by the following.

By employing such a structure of the pressure introduction chamber connected to the pressure introduction port, the movable diaphragm bends due to the pressure difference between the first surface side and the second surface side of the substrate, and this is detected as a change in capacitance. can do.

Another feature of the present invention is that in the above-mentioned capacitance type pressure sensor or the method of manufacturing the same, the first and second lower electrodes have an impurity concentration of 5 × 10 ¹⁹ / cm on the silicon substrate.
³ is introduced or formed of an impurity diffusion layer formed, the first and second upper electrodes, the impurity is composed of impurity diffusion layer introduced 5 × 10 ¹⁹ / cm ³ or more silicon film It is.

By forming the lower electrode and the upper electrode by introducing such a high concentration of impurities, the resistance of these electrodes is sufficiently reduced. For this reason, it is possible to prevent the resistance component in the pressure-sensitive capacitance section from adversely affecting the performance of the capacitance detection circuit, for example, the temperature dependency of the sensitivity, the response frequency, and the like, and particularly improve the response frequency, that is, the response of the sensor. It becomes possible.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments according to the present invention (hereinafter, referred to as embodiments) will be described below in detail with reference to the drawings.

[Basic Configuration] FIG. 1 shows an example of a basic configuration of a capacitance type pressure sensor according to the present invention.
FIG. 2 is a sectional view taken along line AB in FIG. 1. FIG.
FIG. 2 is a sectional view taken along the line CD of FIG. 1.

In the capacitance type pressure sensor of the present invention, the reference capacitance portion 6 is provided on the substrate 50 made of, for example, single crystal silicon.
00 and a pressure-sensitive capacitance section 500 having a lower electrode, a pressure reference chamber, and a movable diaphragm.

A region is formed on the surface of the substrate 50 so as to contain p-type or n-type impurities at a high concentration.
With this region, the first lower electrode 60, the first lower electrode lead 61, and the first lower electrode connection terminal 62 are formed in the pressure-sensitive capacitance section 500, and the second lower electrode 70, A second lower electrode lead 71 and a second lower electrode connection terminal 72 are configured.

The entire surface of the substrate 50 is coated with a substrate protective film 80 having etching resistance as required. A sacrificial film 90 having isotropic etching characteristics is previously formed on the surface of the substrate protection film 80 so as to cover a pressure-sensitive capacitance portion forming region (hereinafter, referred to as a pressure receiving region). A first insulating diaphragm film 100 is formed on the main surface of the substrate 50 so as to cover the sacrificial film 90 over the entire area.

A first upper electrode 110 is disposed in a pressure receiving region on the first insulating diaphragm film 100, and a first upper electrode lead 111 is provided outside the pressure receiving region from the first upper electrode 110. The first upper electrode connection terminal 112 is drawn out and further configured. A second upper electrode 120 is formed on the first insulating diaphragm film 100 at a position facing the second lower electrode 70 in the reference capacitance portion forming region. , A second upper electrode lead 121 is drawn out, and further a second upper electrode connection terminal 122 is formed. The first and second upper electrodes 110 and 120 and the first and second
In this case, the upper electrode leads 111 and 121 and the first and second upper electrode connection terminals 112 and 122 are
All are formed from the same semiconductor film 170. For example, when a polycrystalline silicon film is used as the semiconductor film 170, the semiconductor film 170 made of the polycrystalline silicon film is processed so as to contain p-type or n-type impurities at a high concentration, so that high conductivity characteristics are obtained. I do. The second insulating diaphragm film 130 is formed so as to cover the semiconductor film 170. As the first and second insulating diaphragm films, for example, a silicon nitride film formed by low-pressure CVD is used.

In the present invention, a thermal stress relaxation film 200 having a predetermined thickness is formed so as to cover the second insulating diaphragm film 130. This thermal stress relaxation film 20
Numeral 0 is formed using a material having a coefficient closer to the thermal expansion coefficient of the substrate 50 than the first and second insulating diaphragm films, and is, for example, a silicon nitride film formed by plasma CVD.

As shown in FIGS. 1 and 3, the first upper electrode connection hole 113 is formed in the second insulating diaphragm film 13.
The second upper electrode connection hole 123 is formed so as to reach the first upper electrode connection terminal 112 through the first upper electrode connection terminal 112. Then, the first insulating diaphragm film 100
The first upper electrode 110 is connected to the first upper electrode output terminal 115 through the second upper electrode output terminal 125, and the second upper electrode 120 is connected to the second upper electrode output terminal 125 through the second upper electrode connection hole 123. It is connected.

The first and second lower electrode connection holes 6
3 and 73 are formed so as to penetrate the first insulating diaphragm film 100 and the second insulating diaphragm film 130 and reach the corresponding first and second lower electrode connection terminals 62 and 72, respectively. . For this reason, the first lower electrode 60 is connected to the first lower electrode 60 through the first lower electrode connection hole 63.
Is connected to the lower electrode output terminal 65 of Also, the second
The second lower electrode 70 is connected to the second lower electrode output terminal 75 via the lower electrode connection hole 73.

At a predetermined position in the pressure receiving region, at least one first etching solution inlet 141 which penetrates the first insulating diaphragm film 100 and the second insulating diaphragm film 130 and reaches the sacrificial film 90. Are formed.
The sacrificial film 9 is formed through the first etching solution inlet 141.
Of the first lower electrode 6
A gap serving as the pressure reference chamber 400 is formed between the first diaphragm membrane 0 and the first insulating diaphragm film 100.

When the capacitance type pressure sensor of the present invention is used as an absolute pressure measurement type, after the sacrificial film 90 is removed,
In a vacuum atmosphere, the thermal stress relaxation film 200 is
When the coating is formed on the main surface of the thermal stress relieving film 20 at the same time,
0 seals. As a result, a vacuum pressure reference chamber 400 surrounded by the substrate 50 and the first insulating diaphragm film 100 is formed, and at the same time, the pressure reference chamber 4
The movable diaphragm 300 separated from the substrate 50 is formed on the upper surface side of the substrate 00. In addition, the movable diaphragm 300
Are the first insulating diaphragm film 100 and the semiconductor film 17
0, a second insulating diaphragm film 130 and a thermal stress relaxation film 200.

Here, the feature of the present invention is that, compared with the thermal expansion coefficients of the first and second insulating diaphragm films 100 and 130, the thermal stress relaxation film 200 close to the substrate 50 is formed. Substrate 50
It has approached to.

For example, using a (100) plane single crystal silicon wafer (coefficient of thermal expansion: 3.2 × 10 ⁻⁶ / ° C.) having a diameter of 100 mm and a thickness of 500 μm as the substrate 50, If a silicon nitride film (coefficient of thermal expansion: 2.5 × 10 ⁻⁶ / ° C.) is formed by low-pressure CVD to have a thickness of 200 nm for both the insulating diaphragm films 100 and 130, and the thermal stress relaxation film is not formed, The thermal stress generated in the movable diaphragm due to the difference in thermal expansion coefficient between the movable diaphragm and the substrate due to the change in the ambient temperature is 0.25MP.
a / ° C. On the other hand, as in the present invention, a silicon nitride film (thermal expansion coefficient: 2.8 × 10 ⁻⁾ is formed as a thermal stress relaxation film 200 on the second insulating diaphragm film 130 by plasma CVD close to the thermal expansion coefficient of the substrate 50. ⁶ / ° C.) with a thickness of 1.5 μm, the thermal stress generated in the movable diaphragm 300 due to the change in the ambient temperature of the sensor is 0.1%.
It can be seen that the sensor can be reduced to about 4 MPa / ° C. and the temperature characteristics of the sensor zero point and sensitivity are small.

Further, by taking the capacitance difference from the reference capacitance portion 600 formed close to the pressure-sensitive capacitance portion 500, the influence of the temperature characteristic due to the temperature change of the dielectric constant of the silicon nitride film or the like can be offset. And the temperature dependence of the zero point and the sensitivity can be reduced.

When the capacitance type pressure sensor of the present invention is used as an absolute pressure measurement type, the entire first etching solution inlet 141 is sealed by the thermal stress relaxation film 200 in a vacuum atmosphere as described above. . As a result, the pressure reference chamber 400 is evacuated, and the movable diaphragm 300 of the pressure-sensitive capacitance section 500 is bent in proportion to the applied absolute pressure, and the first lower electrode 60 and the first upper electrode 110 are bent by this bending. Then, the capacitance of the capacitor formed changes. On the other hand, the capacitance of the capacitor formed by the second lower electrode 70 and the second upper electrode 120 of the reference capacitance section 600 does not change. Therefore, by taking the difference in capacitance, the absolute pressure applied to the movable diaphragm 300 can be measured, and the influence of the temperature around the sensor can be canceled.

[Manufacturing Method] Next, an example of a manufacturing method of the capacitance type pressure sensor according to the present invention will be described.

First, a first lower electrode 60, a first lower electrode lead 61, and a first lower electrode 60 containing a high concentration of p-type or n-type impurities by ion implantation or thermal diffusion on the surface of a substrate 50 made of single crystal silicon. A lower electrode connection terminal 62 of
The second lower electrode 70, the second lower electrode lead 71, the second
Is formed. Next, an entire surface of the substrate 50 is coated with a substrate protective film 80 having etching resistance, and a surface of the substrate protective film 80 is coated with a sacrificial film 90 having isotropic etching characteristics. The periphery of the pressure receiving region of the film 90 is removed by etching.

Next, the first insulating diaphragm film 10 is formed so as to cover the sacrificial film 90 over the entire main surface of the substrate 50.
0 is coated. Next, a semiconductor film 170 is formed on the surface of the first insulating diaphragm film 100 by coating. For example, in the case where a polycrystalline silicon film is used for the semiconductor film 170, a process is performed so as to contain p-type or n-type impurities at a high concentration by ion implantation or thermal diffusion and to obtain high conductivity characteristics.

After forming the semiconductor film 170, the first upper electrode 110 formed on the first insulating diaphragm film 100 in the pressure receiving region, the first upper electrode lead 111 formed outside the pressure receiving region, and the first upper electrode The electrode connecting terminal 112 and the first insulating diaphragm film 1 at a position facing the second lower electrode
The semiconductor film 170 around the second upper electrode 120, the second upper electrode lead 121, and the second upper electrode connection terminal 122 formed on the second upper electrode 120 is removed by etching to obtain a desired pattern. After that, a second insulating diaphragm film 130 is formed so as to cover the semiconductor film 170 over the entire main surface of the substrate 50.

Further, at a predetermined position of the pressure receiving region, at least one first etching solution is injected so as to reach the sacrificial film 90 through the second insulating diaphragm film 130 and the first insulating diaphragm film 100. An inlet 141 is formed. Then, the sacrificial film 90 is entirely removed by etching by injecting the etchant through the first etchant inlet 141, and the sacrificial film 90 is provided between the substrate 50 and the first insulating diaphragm film 100. The pressure reference chamber 400 having a size according to the shape and size of the pressure reference chamber 400 is formed. For example, the sacrificial film 90
When polycrystalline silicon is used, an etchant used for etching and removing the sacrificial film 90 uses an aqueous solution of tetramethylammonium hydroxide (TMAH). Since the first and second insulating diaphragm films 100 and 130 located on the upper surface side of the pressure reference chamber 400 have etching resistance to the TMAH aqueous solution, they are not removed by etching.

Next, the second insulating diaphragm film 130
Through the first upper electrode connection terminal 112
Upper electrode connection hole 113 and second upper electrode connection terminal 1
A second upper electrode connection hole 123 reaching 22 is formed.
A first lower electrode connection hole 63 that penetrates through the second insulating diaphragm film 130, the first insulating diaphragm film 100, and the substrate protection film 80 to reach the first lower electrode connection terminal 62; A second lower electrode connection hole 73 reaching the lower electrode connection terminal 72 is formed.

After the formation of each electrode connection hole, aluminum is formed on the entire surface of the substrate 50 so as to cover the first upper electrode output wiring 114, the first lower electrode output wiring 64, the second upper electrode output wiring 124, and the second upper electrode output wiring 124. The aluminum at the periphery of the lower electrode output wiring 74 area of No. 2 is removed by etching. As a result, the first upper electrode 110 is connected to the first upper electrode connection hole 1.
13. The first lower electrode 60 is connected to the first upper electrode output terminal 115 through the first upper electrode output wiring 114;
Is connected to a first lower electrode output terminal 65 via a first lower electrode connection hole 63 and a first lower electrode output wiring 64,
The second upper electrode 120 has a second upper electrode connection hole 123,
The second lower electrode 70 is connected to the second upper electrode output terminal 125 via the second upper electrode output wiring 124.
Is connected to a second lower electrode output terminal 75 via a lower electrode connection hole 73 and a second lower electrode output wiring 74.

When the capacitance type pressure sensor is used as an absolute pressure measurement type, the thermal stress relaxation is such that the first etching liquid inlet 141 can be hermetically sealed over the entire surface of the substrate 50 in a vacuum atmosphere. The film 200 is formed by coating. Finally, thermal stress is applied so that aluminum of the first upper electrode output terminal 115, the second upper electrode output terminal 125, the first lower electrode output terminal 65, and the second lower electrode output terminal 75 is exposed by photoetching. An opening is formed by removing the relaxing film 200.

For example, a single crystal silicon substrate having a (100) plane orientation is used as the substrate 50, and a silicon nitride film formed by low-pressure CVD is used for both the first and second insulating diaphragm films 100 and 130. Compared to a silicon nitride film formed on the stress relaxation film 200 by low pressure CVD, (10
0) A silicon nitride film formed by plasma CVD having a thermal expansion coefficient close to that of a substrate 50 made of a single crystal silicon wafer having a plane orientation is used. Thereby, the movable diaphragm 3
The coefficient of thermal expansion of 00 approaches that of a substrate 50 made of a single crystal silicon wafer having a (100) plane orientation.

As a result, the first insulating diaphragm film 100 and the semiconductor film 1 located on the upper surface side of the pressure reference chamber 400
70, the temperature dependence of the zero point and the sensitivity of the absolute pressure measurement type capacitance type pressure sensor in which the laminated film of the second insulating diaphragm film 130 and the thermal stress relaxation film 200 functions as the movable diaphragm 300. Can be made smaller.

(Embodiment 1) Hereinafter, Embodiment 1 of the present invention will be described.
Will be described.

First, the capacitance type pressure sensor according to the first embodiment will be described with reference to FIGS. 1 to 3 used in the description of the basic configuration example.

As the substrate 50, an n-type (100) single crystal silicon substrate is used. On the main surface of the single-crystal silicon substrate 50, boron is added as an impurity at a high concentration using an ion implantation method, diffused, and processed into a p-type semiconductor to form a first lower electrode 60 having a depth of 2 μm. A first lower electrode lead 61, a first lower electrode connection terminal 62, a second lower electrode 70, a second lower electrode lead 71, and a second lower electrode connection terminal 72 are formed.

Next, as a substrate protective film 80 having etching resistance over the entire surface of the single crystal silicon substrate 50, a silicon nitride film formed by low pressure CVD with a thickness of 100 n
m. A sacrificial film 90 is formed on the surface of the substrate protective film 80 so as to cover the pressure receiving region. This sacrificial film 90 has isotropic etching characteristics, and is removed by etching in a later step. In this embodiment, the sacrificial film 90 is made of polycrystalline silicon having a thickness of 200 nm formed by low-pressure CVD.

After forming the sacrificial film 90, the single crystal silicon substrate 5
A first insulating diaphragm film 100 is formed so as to cover the sacrificial film 90 over the entire area of the main surface 0. The first insulating diaphragm film 100 is formed by coating a silicon nitride film to a thickness of 200 nm by low pressure CVD.

On the surface of the first insulating diaphragm film 100, as the semiconductor film 170, a 200-nm-thick polycrystalline silicon film is formed by low-pressure CVD. The first upper electrode 110, the first upper electrode lead 111, the first upper electrode connection terminal 112, the second upper electrode 120, the second upper electrode lead 121, the first upper electrode 110, the first upper electrode lead 111, 2 upper electrode connection terminal 122
To form In the present embodiment, the semiconductor film 170 made of polycrystalline silicon contains boron at a high concentration using an ion implantation method, and is processed into a p-type semiconductor to obtain high conductivity characteristics.

Next, a second insulating diaphragm film 130 is formed so as to cover this semiconductor film 170 over the entire main surface of single crystal silicon substrate 50. The second insulating diaphragm film 130 is formed by coating a silicon nitride film to a thickness of 200 nm by low pressure CVD.

Next, at a predetermined position in the pressure receiving region, a first etching liquid injection port having a diameter of 10 μm which reaches the sacrificial film 90 through the second insulating diaphragm film 130 and the first insulating diaphragm film 100. An opening 141 is formed by photoetching. Then, by injecting the etching solution through the first etching solution injection port 141, the sacrificial film 90 formed at the beginning is entirely removed by etching, and the single crystal silicon substrate 50 and the first insulating diaphragm film 100 are removed. In between, a cavity is formed to be a pressure reference chamber 400 having a size according to the shape and size of the sacrificial film 90.
In this embodiment, an aqueous solution of tetramethylammonium hydroxide (TMAH) is used as the etching solution. At this time, the substrate protective film 80 located on the lower surface side of the pressure reference chamber 400 and the first and second insulating diaphragm films 100 and 130 located on the upper surface side have etching resistance to the TMAH aqueous solution. It is not removed by etching.

Next, the second insulating diaphragm film 130
Through the first upper electrode connection terminal 112
Upper electrode connection hole 113 and second upper electrode connection terminal 1
A second upper electrode connection hole 123 reaching 22 is formed by photoetching. A first lower electrode connection hole 63 that penetrates through the second insulating diaphragm film 130, the first insulating diaphragm film 100, and the substrate protection film 80 to reach the first lower electrode connection terminal 62; A second lower electrode connection hole 73 reaching the lower electrode connection terminal 72 is formed by photoetching.

Thereafter, the second on the single crystal silicon substrate 50
The first upper electrode output wiring 114 and the first lower electrode output wiring 6 are provided at predetermined portions on the insulating diaphragm film 130 of FIG.
4. The second upper electrode output wiring 124 and the second lower electrode output wiring 74 are formed. These wirings are formed by vacuum-depositing or sputtering aluminum over the entire surface of the single-crystal silicon substrate 50 to a thickness of 800 nm, and removing unnecessary portions of the aluminum by photoetching. At this time, the first upper electrode 11
0 is connected to the first upper electrode output terminal 115 via the first upper electrode connection hole 113 and the first upper electrode output wiring 114, and the first lower electrode 60 is connected to the first lower electrode connection hole 6.
3. Connected to the first lower electrode output terminal 65 via the first lower electrode output wiring 64. Also, the second upper electrode 1
Reference numeral 20 denotes a second upper electrode output terminal 125 via a second upper electrode connection hole 123 and a second upper electrode output wiring 124.
The second lower electrode 70 is connected to a second lower electrode output terminal 75 via a second lower electrode connection hole 73 and a second lower electrode output wiring 74.

When the capacitance type pressure sensor of this embodiment is used as an absolute pressure measurement type, the first etching solution inlet 141 can be hermetically sealed over the entire surface of the single crystal silicon substrate 50 in a vacuum atmosphere. A thermal stress relaxation film 200 having a thickness of about a thickness is formed. In this embodiment, the thermal stress relaxation film 200 is a silicon nitride film formed by a plasma CVD method, and has a thickness of 1.2 μm.

After the thermal stress relieving film 200 is formed, a predetermined position of the thermal stress relieving film 200 is removed by photoetching to form an opening, thereby forming the first upper electrode output terminal 11.
5. The aluminum of the second upper electrode output terminal 125, the first lower electrode output terminal 65, and the second lower electrode output terminal 75 is exposed.

As described above, the thermal stress relaxation film 2 in a vacuum state
By forming 00, the pressure reference chamber 400 is sealed by the thermal stress relaxation film 200, and the pressure reference chamber 400 is in a vacuum state.

Accordingly, the movable diaphragm 300 of the pressure-sensitive capacitance section 500 flexes in proportion to the applied absolute pressure, and the flexure causes the pressure detection formed by the first lower electrode 60 and the first upper electrode 110 to be detected. The capacitance of the capacitor C _X changes.

Meanwhile, the capacitance of the reference capacitor C _R to the second lower electrode 70 of the reference capacitor portion 600 is formed by the second upper electrode 120 is not changed. Therefore, by taking the difference in capacitance, the absolute pressure applied to the movable diaphragm 300 can be measured, and the influence of the temperature around the sensor can be canceled.

One of the methods of detecting a change in capacitance in the sensor according to the present embodiment is a charge / discharge type switched capacitor circuit for converting capacitance to voltage. FIG.
Shows a switched capacitor type capacitance detection circuit.

In this circuit, four switches SW1 to S
W4, and the four switches SW1 to SW4
Are switched by a clock signal of a predetermined frequency. SW1 and SW2 are alternately connects one end of the pressure detecting capacitor C _X and the reference capacitor C _R to the ground or power V _P. In other words, any plug one capacitor C _X or C _R to ground, connecting the other to the power supply V _P.

The other ends of the pressure detection capacitor C _X and the reference capacitor C _R are connected to the negative input terminal of the operational amplifier. The positive input terminal of the operational amplifier is connected to the ground. A feedback capacitor _CF and a switch SW3 are connected in parallel between the output terminal and the negative input terminal of the operational amplifier. The output of the operational amplifier is connected to an output terminal via a switch SW4. A smoothing capacitor C _O whose other end is connected to the ground is connected to the output end of the circuit.

[0072] In the example of the circuit of FIG. 4, when the switch SW1 is connected to the power supply V _P is, SW2 is connected to ground, SW3 are turned on (closed), SW4 is turned off (open), and the switch SW2 is power when connected to the V _P is, SW1 is connected to ground, SW3 is turned off, SW4 is turned on.

In the switched capacitor circuit, C _X , C _R , and C _F are substantially made resistors by switching, and the amplification factor of the operational amplifier is determined by the input-side capacitance (two capacitances C _X and C _R).
Are alternately connected, the ratio is determined by the ratio between the difference) and the capacitance on the feedback side. Therefore, assuming that the output voltage of this switched capacitor circuit is E ₀ , this E ₀ becomes E ₀ = V _P (C
_X− C _R ) / C _F , and the output voltage E ₀ can detect the capacitance difference between the two capacitors C _X and C _R. Here, the capacitor C _X corresponds to a pressure-sensitive capacitance portion, and the capacitor C _R
Corresponds to a reference capacitance section. Therefore, the applied pressure can be detected by the circuit of FIG.

As a result of connecting the sensor of this embodiment to the switched-capacitor type capacitance detecting circuit having such a configuration and measuring the sensor characteristics, the absolute pressure of 100 kPa was obtained.
The output voltage is 0.03 V or more, and the nonlinearity of the output voltage characteristic with respect to the applied pressure is -1.6% F. S. Below, -30 to
In the temperature range of 80 ° C., it was confirmed that the temperature coefficient of the zero point and the temperature coefficient of the sensitivity had excellent temperature characteristics of 500 ppm / ° C. and −300 ppm / ° C., respectively.

As described above, according to the capacitance type pressure sensor of this embodiment, in the manufacture of an LSI, it can be manufactured in a small size by using a thin film material generally used, and has a zero point and sensitivity. It can be understood that a capacitance-type pressure sensor having a small temperature dependency can be realized.

In this embodiment, a silicon nitride film formed by plasma CVD with a thickness of 1.5 μm is used as the thermal stress relaxation film 200. By changing the thickness of the silicon nitride film, it is possible to control the thermal stress generated in the movable diaphragm 300 due to the change in the ambient temperature. Hereinafter, the relationship between the thickness of the thermal stress relaxation film 200 and the thermal stress of the movable diaphragm will be described with reference to FIG.

In FIG. 5, on a single crystal silicon substrate 50,
First and second insulating diaphragm films 100 and 130
The silicon nitride film to a thickness of 400
3 shows the results of measurement of thermal stress when a silicon nitride film was formed thereon by a plasma CVD method used for the thermal stress relaxation film 200 and the formed film thickness was changed. Here, the thermal stress was determined based on the amount of warpage of the single crystal silicon substrate 50 due to a change in ambient temperature.

From the results shown in FIG. 5, the thermal stress relaxation film has a thickness of 0.7 μm.
When the thickness becomes the above-mentioned thickness, the thermal stress generated in the movable diaphragm becomes about 0.15 MPa / ° C. or less, and when the thermal stress relaxation film is subsequently thickened, the thermal stress further decreases, and the film thickness becomes 1.
In the region of 5 μm or more, the thermal stress is further reduced, but the rate of reduction is small. From the above, for example, the thickness of the thermal stress relaxation film is 1.0 μm or 2.0 μm, that is, the thickness ratio of the silicon nitride film of plasma CVD to the silicon nitride film of low pressure CVD is about 2.5 to 5.0 Then, it can be seen that the thermal expansion coefficient of the entire movable diaphragm can be made close to the coefficient (3.2 × 10 ⁻⁶ / ° C.) of the single crystal silicon substrate, and the thermal stress in the movable diaphragm becomes small.

The sensor using a silicon nitride film formed by plasma CVD with a thickness of 1.5 μm on the thermal stress relaxation film 200 in the above-described embodiment is 100 k.
The output voltage is 0.02 V or more with respect to the absolute pressure of Pa,
Non-linearity of output voltage characteristics to applied pressure is -1.1%
F. S. Below, in the temperature range of -30 to 80 ° C,
Temperature coefficient of zero point and sensitivity is 1500 ppm each
/ ° C and -200 ppm / ° C.

(Embodiment 2) Next, a preferred embodiment 2 of the present invention will be described. Members corresponding to those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

FIG. 6 is a sectional view showing a capacitance type pressure sensor according to the second embodiment.

First, a first lower electrode 60 and a second lower electrode 70 are formed on the main surface of a single crystal silicon substrate 50.
Next, a 100 nm-thick silicon nitride film is formed over the entire surface of the single crystal silicon substrate 50 as a substrate protective film 80 having etching resistance by a low pressure CVD method. A sacrificial film 90 made of a polycrystalline silicon film having a thickness of 200 nm is formed on the surface of the substrate protection film 80 on the pressure receiving region on the first lower electrode 60 and on the second lower electrode 70.

Next, as in the first embodiment, a first insulating diaphragm film 100 and a semiconductor film 170 are formed. By photo-etching this semiconductor film 170,
A first upper electrode 110 and a second upper electrode 120 are formed. Next, a second insulating diaphragm film 130 is formed so as to cover the semiconductor film 170 over the entire main surface of the single crystal silicon substrate 50. Further, a first etching liquid injection port 141 and a second etching liquid injection port 142 having a diameter of 10 μm that reach the sacrificial film 90 through the second insulating diaphragm film 130 and the first insulating diaphragm film 100 are formed. An opening is formed by photoetching.
By injecting the obtained tetramethylammonium hydroxide (TMAH) etching solution through the obtained first etching solution injection port 141 and second etching solution injection port 142, all of the sacrificial film 90 initially formed is completely removed. Remove by etching. Thereby, the sacrificial film 90 is placed between the single crystal silicon substrate 50 and the first insulating diaphragm film 100.
And a cavity serving as the pressure introduction chamber 150 are formed.

The wiring of each electrode is formed in the same manner as in the first embodiment.

Next, in a vacuum atmosphere, the entire surface of the single-crystal silicon substrate 50 is applied with a thickness of 1.2 μm by plasma CVD.
Then, a thermal stress relaxation film 200 made of a silicon nitride film having a thickness of m is formed. Then, the thermal stress relaxation film 200 on the second etchant injection port 142 is removed by photoetching, and the pressure introduction port 16 for introducing an applied pressure to the pressure introduction chamber 150 is removed.
0 is formed.

As a result, the movable diaphragm 300 is formed on the pressure-sensitive capacitance portion side, and the immovable membrane 350 is formed on the reference capacitance portion side. The movable diaphragm 300
It is composed of a first insulating diaphragm film 100 located on the upper surface side of the pressure reference chamber 400, a semiconductor film 170 thereon, a second insulating diaphragm film 130 on the semiconductor film 170, and a thermal stress relaxation film 200. . In addition, the immobile membrane 350 includes the first insulating diaphragm film 100 located on the upper surface side of the pressure introducing chamber 150, the semiconductor film 170 thereon, the second insulating diaphragm film 130 on the semiconductor film 170, and the thermal stress relaxation. It is composed of a film 200.

The movable diaphragm 300 of the pressure-sensitive capacitance section 500 flexes in proportion to the applied absolute pressure, and the flexure causes the first lower electrode 60 and the first upper electrode 110 to flex.
The capacitance of the capacitor C _X formed by the above changes.
However, since the pressure around the sensor and the pressure in the pressure introducing chamber 150 are the same, the immobile membrane 350 does not bend due to the applied pressure. Therefore, the capacitance of the capacitor C _R formed by the second and the lower electrode 70 and the second upper electrode 120 of the reference capacitance 600 does not change.
Therefore, the absolute pressure applied to the movable diaphragm 300 can be measured by taking the difference between the capacitances of the two capacitors C _X and C _R. In particular, since these two capacitors have substantially the same configuration, the two capacitors C _X and C _{R have} the same temperature dependence, so that the influence of the temperature around the sensor can be accurately canceled.

As a result of connecting the sensor of this embodiment to a switched-capacitor type capacitance detection circuit and measuring the sensor characteristics, the output voltage was 0.1 kPa for an absolute pressure of 100 kPa.
03 V or higher, the nonlinearity of the output voltage characteristic with respect to the applied pressure is -1.6% F. S. Hereinafter, in the temperature range of -30 to 80 ° C, the temperature coefficients of the zero point and the sensitivity are 3
It was confirmed to have excellent temperature characteristics of 00 ppm / ° C. and −300 ppm / ° C.

(Embodiment 3) FIG. 7 shows a plan configuration of a capacitance type pressure sensor according to Embodiment 3 of the present invention.

The third embodiment is provided with a configuration for increasing the amount of change in the capacitance with respect to the applied pressure without deteriorating the linearity of the output voltage characteristic with respect to the applied pressure.

In the third embodiment, the single crystal silicon substrate 50
A plurality of pressure-sensitive capacitance units 500 and reference capacitance units 600 having the configurations described in the first and second embodiments are connected in parallel at predetermined positions. The shapes and dimensions of the pressure-sensitive capacitance section 500 and the reference capacitance section 600 are as follows.
This is the same as that shown in the above embodiment. However,
The shapes and dimensions do not necessarily have to be the same.

In the example shown in FIG. 7, 16 pressure-sensitive capacitance units 500 and 16 reference capacitance units 600 are connected and arranged. First upper electrode 11 of 16 pressure-sensitive capacitance units 500
0 are connected in parallel by the first upper electrode connection wiring 510. Further, the second upper electrodes 120 of the sixteen reference capacitance units 600 are connected in parallel by the second upper electrode connection wiring 610.

The sensor of the third embodiment was connected to a switched-capacitor type capacitance detecting circuit as shown in FIG. 4, and the sensor characteristics were measured. As a result, the output voltage was 0.5 V or more with respect to the absolute pressure of 100 kPa. Met. Further, the nonlinearity of the output voltage characteristic with respect to the applied pressure is -1.6% F.
S. Below, in the temperature range of -30 to 80 ° C, it was confirmed that the temperature coefficient of the zero point and the sensitivity had excellent temperature characteristics of ± 500 ppm / ° C or less.

(Embodiment 4) FIG. 8 shows a plan configuration of a capacitance type pressure sensor according to Embodiment 4.

In the present embodiment, the capacitance type pressure sensor having the configuration as in the above-described embodiment and an integrated capacitance detection circuit as shown in FIG. 4, for example, are integrated.

In FIG. 8, the pressure-sensitive capacitance section 500 and the reference capacitance section 600 described in the first and second embodiments are formed at predetermined positions of the single-crystal silicon substrate 50. Further, a circuit portion 700 is formed on the single crystal silicon substrate 50 by using a semiconductor manufacturing technique. The circuit section 700 can be composed of, for example, a switched-capacitor type capacitance detection circuit that converts a capacitance change into a voltage as shown in FIG.

First upper electrode 11 of pressure-sensitive capacitance section 500
0 and the first lower electrode 60 are connected to the circuit section 700 via the first upper electrode output terminal 115 and the first lower electrode output terminal 65, respectively. Also, the reference capacitance section 600
The second upper electrode 120 and the second lower electrode 70 are connected to the circuit section 700 via the second upper electrode output terminal 125 and the lower electrode output terminal 75, respectively. When the switched capacitor type capacitance detection circuit shown in FIG. 4 is adopted, the first upper electrode 110 and the first lower electrode 60
Is electrically connected to the electrode of the capacitor C _X of FIG. 4, and the second upper electrode 120 and the second lower electrode 70 are electrically connected to the electrode of the capacitor C _R of FIG. It will be.

As described above, for example, in the circuit shown in FIG. 4, the operational amplifier, switches, capacitors, and the like can be integrated on a single crystal silicon substrate. Therefore, if such a capacitance detection circuit portion is integrated on the same substrate as the sensor, a capacitance type pressure sensor that can obtain an electrical output can be manufactured by one semiconductor processing process.
A so-called integrated pressure sensor integrated with an integrated circuit can be easily manufactured.

(Embodiment 5) The feature of Embodiment 5 is that in the first and second lower electrodes 60 and 70, the impurity to be implanted into the substrate 50 is at a high concentration, specifically 5 × 10 ¹⁹ / cm 3.
³ , the first and second upper electrodes 110, 1
Also in the case of 20, the impurity to be implanted into the polycrystalline silicon film 170 is implanted at a higher concentration, specifically, 5 × 10 ¹⁹ / cm ³ . The resistance value of the first and second lower electrodes 60 and 70 formed by introducing the high-concentration impurities is 60Ω, and the first and second upper electrodes 110 and 12 are formed.
The resistance value of 0 is 1 kΩ, which can be a very low value.

[0100] response of the capacitance detection circuit as shown in FIG. 4 is inversely proportional to the capacitance C _x and the product of the resistance R of the pressure sensitive capacitance section which is input to the operational amplifier unit. Therefore, high responsiveness can be obtained by reducing the resistance of the upper electrode and the lower electrode. The voltage supplied from the capacitance detection circuit to the pressure-sensitive capacitance unit (C _x ) determines the magnitude of the output voltage of the sensor.
For this reason, by lowering the resistance values of the upper and lower electrodes, it is possible to prevent the sensitivity temperature characteristics from being degraded due to the leak current at the pn junction, and it is possible to reduce the temperature dependence of the sensitivity.

FIG. 9 is a graph showing the resistance value of the lower electrode (horizontal axis) and the temperature coefficient of the sensitivity of the obtained capacitance type sensor (vertical axis: ppm).
/ ° C .: ppm = 10 ⁻⁶ ). Also,
FIG. 10 shows the relationship between the resistance value of the upper electrode (horizontal axis) and the response frequency of the sensor (vertical axis: kHz). If the resistance value of the lower electrode becomes 60Ω by setting the impurity concentration to 5 × 10 ¹⁹ / cm ³ as in the fifth embodiment, as can be seen from FIG. 300
ppm / ° C. Therefore, the same characteristic is obtained by comparing the absolute value and the temperature coefficient of the sensitivity of the sensor obtained in each of the above embodiments. Also, as in the fifth embodiment, by setting the impurity concentration of the upper electrode to 5 × 10 ¹⁹ / cm ³ , the resistance value of the upper electrode is 1 kΩ.
0, the response frequency of the sensor is, for example, 10
0 kHz has been realized.

Here, in the conventional sensor shown in FIG. 15, when the impurity implantation concentration in the lower electrode 11 and the upper electrode 14 was set to 1 × 10 ¹⁹ / cm ³ , the characteristics of the sensor were examined. Is 200Ω, the resistance of the upper electrode is 10kΩ, and the temperature coefficient of sensitivity is -1000pp.
m / ° C., and the response frequency was 10 kHz.

Therefore, by reducing the resistance of the lower electrode and the upper electrode as in the fifth embodiment, the temperature coefficient of the sensitivity of the sensor can be reduced to one third or less of that of the conventional sensor, and the response frequency can be reduced to about 10 times. It can be seen that the above can be achieved.

(Embodiment 6) FIG. 11 is a plan view of a capacitance type pressure sensor according to Embodiment 6, and FIG.
13 is a diagram showing a cross section taken along line EF, and FIG. 13 is a diagram showing a cross section taken along line GH in FIG. Embodiment 1 described above
5 to 5 relate to a capacitance type pressure sensor for measuring an absolute pressure applied to a movable diaphragm, and the sixth embodiment is a capacitance type pressure sensor for measuring a relative pressure. This is different from the embodiment.

In this capacitance type pressure sensor, the pressure reference chamber is not sealed, and the pressure P ₁ applied to the first surface (main surface) of the silicon substrate 50 and the pressure P ₁ applied to the second surface (back surface) capacitance due to the pressure difference between the pressure P ₂ applied from the the pressure sensitive capacitance portion 500 which changes the reference capacitor portion 600 does not change in capacitance is constituted by juxtaposed.

The pressure-sensitive capacitance section 500 includes a first lower electrode 60 formed on the first surface side of the substrate 50, a first pressure introduction port formed on the second surface side of the substrate 50, Pressure reference chamber (pressure introduction chamber) 151 and substrate 5 connected to
0 is provided with a movable diaphragm 300 formed on the main surface side. In addition, the reference capacitance unit 600 includes a second lower electrode 70 formed on the substrate 50, a second pressure inlet 162 formed on the first surface side of the substrate 50, and a second pressure inlet 162 connected to the inlet 162. Pressure reference chamber (pressure introduction chamber) 152, first substrate
An immovable membrane 350 formed on the surface side is provided.

The substrate 50 is an n-type (100) oriented single-crystal silicon substrate. On the first surface side of the substrate, for example, boron as an impurity is doped at a high concentration by ion implantation, specifically, 5 × 10 5 ^A p-type semiconductor region is formed by adding and diffusing so as to have a concentration of ¹⁹ / cm ³ or more. In the impurity region, a first lower electrode 60, a first lower electrode lead 61, and a first lower electrode connection terminal 62 are formed in the pressure-sensitive capacitance portion 500, and a second lower electrode 60 is formed in the reference capacitance portion 600. An electrode 70, a second lower electrode lead 71, and a second lower electrode connection terminal 72 are configured.

Incidentally, the first pressure inlet 161 penetrates through the substrate 50 from the second surface side of the substrate 50 later.
0, the first lower electrode 60
An opening larger than the diameter of the inlet 161 is provided in the central region so as not to be exposed on the side wall of the inlet. Further, the second lower electrode 70 needs to have the same area as the first lower electrode 60, and thus is formed in the same pattern as the first lower electrode 60.

On the first and second surfaces of the substrate 50, a first substrate protection film 80 and a second substrate protection film 82 having etching resistance are formed, respectively. This protective film 8
Numerals 0 and 82 are made of a silicon nitride film formed to a thickness of, for example, 100 nm by low pressure CVD. Further, a sacrificial film 90 made of polycrystalline silicon is previously formed on the formation region of the pressure-sensitive capacitance portion 500 and the reference capacitance portion 600 on the first substrate protection film 80, and the first and second sacrificial films 90 are removed later. 2
Are the pressure introduction chambers 151 and 152. A first insulating diaphragm film 100 is formed so as to cover the sacrificial film 90 and the protective film 80. The first insulating diaphragm film 100 is formed, for example, to 200 nm by low pressure CVD.
Made of a silicon nitride film having a thickness of

A first upper electrode 110 is formed in a pressure-receiving region on the first insulating diaphragm film 100 and opposed to the first lower electrode 60. , The first upper electrode lead 111 is drawn out of the pressure receiving region, and the first upper electrode connection terminal 11
2 are configured. Further, in the reference capacitance portion forming region,
On the first insulating diaphragm film 100, the second upper electrode 120 is located at a position facing the second lower electrode 70.
Are formed, a second upper electrode lead 121 is drawn out from the second upper electrode 120, and a second upper electrode connection terminal 122 is formed.

The first and second upper electrodes 110, 1
20 and first and second upper electrode leads 111 and 121
And the first and second upper electrode connection terminals 112 and 12
2 are all formed from the same semiconductor film 170. This semiconductor film 170 is formed of a polycrystalline silicon film having a thickness of 200 nm formed by low-pressure CVD. Furthermore,
This polycrystalline silicon film 170 has a high concentration of boron as an impurity, for example, by ion implantation, specifically 5 ×.
It is added and diffused by 10 ¹⁹ / cm ³ or more to give p-type conductivity.

Further, the second insulating diaphragm film 130
Are formed so as to cover the semiconductor film 170.
As the first and second insulating diaphragm films, for example, a silicon nitride film formed by low-pressure CVD is used.

Then, as in the other embodiments, the second
The thermal stress relaxation film 200 having a thickness of, for example, 1.5 μm is formed so as to cover the insulating diaphragm film 130. The thermal stress relaxation film 200 is formed using a material having a coefficient closer to the coefficient of thermal expansion of the substrate 50 than the first and second insulating diaphragm films.
It is made of a silicon nitride film formed by plasma CVD.

Next, a method of manufacturing the sensor according to the sixth embodiment will be described focusing on matters different from the above-described embodiment. The substrate 50 is an n-type (100) plane single crystal silicon substrate as described above, and boron is introduced into the first surface side of the substrate by ion implantation at a concentration of 5 × 10 ¹⁹ / cm ³ or more. First lower electrode 60, first lower electrode lead 6
1, first lower electrode connection terminal 62, second lower electrode 7
0, a second lower electrode lead 71, and a second lower electrode connection terminal 72.

After the lower electrodes 60 and 70 are formed on the substrate 50, a first substrate protective film 80 is formed on the first surface side of the substrate 50, and a second substrate protective film 82 is formed on the second surface side. Form.
Next, a sacrificial film 90 is formed on the first substrate protective film 80. Before that, the first substrate protective film 80 is removed only at a predetermined position in the pressure receiving region by a region having a diameter of 10 μm.
A first substrate protective film opening 81 is formed.

On the first surface side of the substrate 50, a sacrificial film 90 is formed, and the sacrificial film 90 is formed on the first and second pressure introducing chambers 15.
After etching into a predetermined pattern corresponding to 1, 152,
First insulating diaphragm film 1 made of a silicon nitride film
00 (thickness: 200 nm).

Further, a polycrystalline silicon film 170 is formed, and an impurity (boron) is added to this film 170 at a high concentration, specifically,
Introducing at least 5 × 10 ¹⁹ / cm ³ and etching into a predetermined pattern, the first upper electrode 110, the first upper electrode lead 111, the first upper electrode connection terminal 112, the second upper electrode 120, the second upper electrode The upper electrode lead 121 and the second upper electrode connection terminal 122 are formed.

Next, a second insulating diaphragm film 130 made of a silicon nitride film is formed so as to cover these upper electrodes, their electrode leads, and the entire connection terminals.
00 nm).

After the formation of the second insulating diaphragm film 130, the second substrate protective film 82 on the second surface side of the substrate 50 has a side of 75
A second substrate protection film opening 83 of 0 μm is formed. Second
After forming the substrate protective film opening 83 of FIG.
On the surface side, in the reference capacitance section 600, the second insulating film 130 having a diameter of about 10 μm that reaches the sacrificial film 90 through the second insulating diaphragm 130 and the first insulating diaphragm 100.
Is formed by photoetching.

Thereafter, for example, an aqueous solution of tetramethylammonium hydroxide is used as an etching solution,
The substrate 50 exposed at the substrate protective film opening 83 is anisotropically etched to form a first pressure inlet 161 penetrating the substrate. Further, the first pressure inlet 161 is used as a first etching liquid inlet, the sacrificial film 90 exposed through the inlet is etched, and the sacrificial film exposed through the second etching liquid inlet 142 is etched. 90 is removed by etching. When the sacrifice film 90 is entirely removed by etching, a cavity serving as the first pressure introduction chamber 151 connected to the first pressure introduction port 161 is formed in the pressure-sensitive capacitance section 500. In the reference capacitance section 600, A cavity that forms the second pressure introduction chamber 152 connected to the second pressure introduction port 162 is formed.

In the sixth embodiment, as described above, the first and second lower electrodes 60 and 70, and the first and second upper electrodes 1
10 and 120 are all formed of a p-type semiconductor into which impurities are implanted at a high concentration, specifically, for example, boron ions implanted at a concentration of 5 × 10 ¹⁹ / cm ^3. Has etching resistance to the aqueous solution of tetramethylammonium hydroxide.

FIG. 14 shows the first pressure inlet 161 formed when the formation position of the second substrate protective film opening 83 is shifted from the ideal position with respect to the first lower electrode 60. The state is shown. Note that FIG. 14 is the same as G in FIG.
FIG. 14 shows a cross section taken along line -H, and the position shown by the dotted line in FIG. 14 is the ideal first pressure introduction port 161.
When the opening 83 is deviated from the ideal position and the anisotropic etching of the substrate 50 proceeds, as shown in a region surrounded by A in the figure, the first lower electrode 60 is connected to the first pressure introducing port. 161 is exposed on the side wall and is in contact with aqueous tetramethylammonium hydroxide. However, the first lower electrode 60 is formed by introducing a high concentration of impurities.
It has resistance to this etchant. For this reason, even if the first lower electrode 60 is exposed to the etching solution, the erosion received by the first lower electrode 60 is small, and the first pressure introducing chamber 151 similar to the case where the first pressure introducing port 161 is formed at an ideal position is formed. This prevents the change in capacitance in the pressure-sensitive capacitance section 500 and the influence on the sensor characteristics.

If there are minute defects in the second and first insulating diaphragm films 130 and 100, the first and second upper electrodes 110 and 120 are not etched during the etching with the tetramethylammonium hydroxide aqueous solution. May be exposed to this aqueous tetramethylammonium hydroxide solution. However, the first and second upper electrodes 110,
120 also has a high concentration (5 × 10 ¹⁹ / cm ³ ) of impurities implanted in the polycrystalline silicon film as in the case of the lower electrode, and has an etching resistance to an aqueous solution of tetramethylammonium hydroxide. Therefore, both the lower electrode and the upper electrode are hardly etched, and the sensor element can be stably formed.

The first pressure introducing chamber 15 is provided in the pressure-sensitive capacity section 500.
1 and the second pressure introduction chamber 15
After forming the second, the first upper electrode connection hole 113 reaching the first upper electrode connection terminal 112 and the second upper electrode connection terminal 122 so as to penetrate the first insulating diaphragm film 130. A second upper electrode connection hole 123 is formed. Further, the second and first insulating diaphragms 13
0, 100, a first lower electrode connection hole 63 penetrating through the first substrate protective film 80 and reaching the first lower electrode connection terminal 62, and a second lower electrode reaching the second lower electrode connection terminal 72. The lower electrode connection hole 73 is formed.

After the formation of each connection hole, aluminum is coated on the entire first surface side of the substrate 50, and this connection hole is filled with aluminum to connect the conductive regions above and below the connection hole.
As a result, the first and second lower electrodes 60 and 70 are connected to the first and second lower electrode output terminals 65 and 75, respectively, and the first and second upper electrodes 110 and 120 are respectively connected to the first and second lower electrodes 110 and 120. And second upper electrode output terminals 115 and 125
Connected to.

Further, the second insulating diaphragm film 130
Plasma CV as thermal stress relaxation film 200 so as to cover
D forms a silicon nitride film to a thickness of 1.5 μm. Finally, the thermal stress relaxation film on the first and second upper electrode output terminals 115 and 125, the first and second lower electrode output terminals 65 and 75, and the second etchant inlet 142 is formed by photoetching. Remove 200.

In the thus-obtained capacitance type pressure sensor of Embodiment 6, the movable diaphragm 300 is formed on the first pressure introducing chamber 151 in the pressure-sensitive capacitance section 500, and the reference capacitance section 600 Has a second pressure introduction chamber 152
An immobile membrane 350 is formed thereon. The movable diaphragm 300 includes a first insulating diaphragm film 100, a semiconductor film (first upper electrode) 170, a second insulating diaphragm film 130, and a thermal insulating film 100 located on the upper surface side of the first pressure introducing chamber 151. It is composed of a stress relaxation film 200. On the other hand, the immovable membrane 350 includes the first insulating diaphragm film 100, the semiconductor film (second upper electrode) 170, the second insulating diaphragm film 130, and the thermal insulating film located on the upper surface side of the second pressure introducing chamber 152. It is composed of a stress relaxation film 200.

The sensor according to the sixth embodiment having the above-described configuration has the first pressure P in the direction indicated by the arrow in FIG.
_{When the first} and second pressures P ₂ are applied, the movable diaphragm 300 of the pressure-sensitive capacitance section 500 is changed according to the pressure difference between P ₁ and P _2.
Is deformed. The deformation changes the gap between the first upper electrode 110 and the first lower electrode 60 constituting the movable diaphragm 300, and the first upper electrode 110 and the first upper electrode 110
The capacitance (C _x ) of the capacitor formed with the lower electrode 60 changes. Therefore, the pressure difference between the first pressure P ₁ and the first pressure P ₂ is detected by detecting the capacitance. On the other hand, the immovable membrane 350 of the reference capacity section 600
Is the same as the pressure in the pressure introduction chamber 152, and therefore does not bend due to the applied pressure. Therefore, the reference capacitance unit 60
The capacitance (C _R ) of the capacitor formed by the second upper electrode 120 and the second lower electrode 70 does not change.

As described above, the sensor according to the sixth embodiment is connected to the above-described switched-capacitor-type capacitance detection circuit shown in FIG. Pressure) can be detected.

When the sensor of the sixth embodiment is connected to the circuit of FIG. 4, the first lower electrode output terminal 65 of the pressure-sensitive capacitance section 500 is connected to the switch SW1, and the first upper electrode output terminal 115 Connect to the negative input terminal of the operational amplifier. Also,
The second lower electrode output terminal 75 of the reference capacitance unit 600 is connected to the switch SW2 end, and the second upper electrode output terminal 12
5 is connected to the negative input terminal of the operational amplifier. Note that the operational amplifier detects minute charges that have changed in the pressure-sensitive capacitance unit 500 and the reference capacitance unit 600. In the first and second lower electrodes 60 and 70 of the sixth embodiment formed by the p-type diffusion layers, when charge is injected by a leak current from the n-type single crystal silicon substrate 50, the sensor performance deteriorates. I will. Therefore, it is preferable to adopt a configuration in which the upper electrode is connected to the negative input terminal of the operational amplifier as described above.

The sixth embodiment is characterized in that it is a capacitance type differential pressure sensor for detecting a relative pressure, and further comprises a first and a second lower electrode and a first and a second upper electrode. Are characterized by being formed of a high-concentration impurity introduction region of 5 × 10 ¹⁹ / cm ³ or more. By forming the lower electrode and the upper electrode with the high-concentration impurity regions as described above, etching resistance is exhibited at the time of etching the substrate 50 and the sacrificial film, and it is possible to manufacture a sensor having small variations in characteristics. Further, by forming the lower electrode and the upper electrode by the high concentration impurity region,
As in the case of the fifth embodiment, the resistance of these electrodes can be reduced, and this greatly affects the temperature coefficient of the sensitivity of the sensor and the response frequency. Hereinafter, the temperature coefficient of the sensitivity and the resistance of the electrode on the response frequency will be described.

As described in the fifth embodiment, in the conventional sensor shown in FIG. 15, when the lower electrode is formed by introducing boron into the substrate 50 at a concentration of 1 × 10 ¹⁹ / cm ³ , the lower electrode is formed. The resistances of 60 and 70 are about 200Ω. Similarly, when the first and upper electrodes are formed by introducing boron into the polycrystalline silicon film at a concentration of 1 × 10 ¹⁹ / cm ³ , the resistance of the upper electrode becomes 10 kΩ. When the resistance value of the lower electrode is 200Ω, the temperature coefficient of sensitivity is −1000 ppm / ° C., and the resistance value of the upper electrode is 10 k.
In the case of Ω, the response frequency is as high as 10 kHz.

However, by lowering the resistance of the lower electrode and the upper electrode by increasing the impurity concentration as in the sixth embodiment, the response frequency of the sensor is about 10 times or more that of the conventional sensor as shown in FIG. Of 100 kHz. Further, the temperature coefficient of sensitivity is at least equivalent to the absolute value of the above-described first to fifth embodiments, and is lower than that of the conventional sensor as shown in FIG. And can be.

[0134]

As is apparent from the above description, the capacitance type pressure sensor of the present invention has a structure in which the movable diaphragm of the pressure-sensitive capacitance portion has a thermal stress relaxation film using a material close to the thermal expansion coefficient of the substrate. Prepare. Thereby, even if the thermal expansion coefficients of the first and second insulating diaphragm films cannot approach the coefficient of the substrate, the average thermal expansion coefficient of the movable diaphragm can be approximated to the substrate. Therefore, thermal stress generated in the movable tire flam can be reduced, and a sensor having zero temperature and small sensitivity-dependent temperature can be obtained.

Further, by providing the reference capacitance portion close to the pressure-sensitive capacitance portion, if the capacitance difference between these two capacitance portions is obtained, the influence of the temperature can be canceled. Therefore, the temperature dependence of the zero point and the sensitivity of the sensor can be further reduced.

Further, since the movable diaphragm can be formed with high precision by using the thin film forming technique of the semiconductor process and the etching technique of the sacrificial film, it is easy to form a narrow gap between the opposing electrodes constituting the capacitor, and the capacitance is increased. The size of the pressure sensor can be reduced and the sensitivity can be increased. Moreover, since most of the components can be manufactured by processing one surface of the substrate, it is extremely suitable for manufacturing a so-called integrated sensor integrated with an integrated circuit.

Further, the sensor of the present invention is excellent in sensitivity, responsiveness, etc., and can exhibit excellent characteristics as either a sensor for detecting absolute pressure or a sensor for detecting relative pressure.

Further, by sufficiently increasing the impurity concentrations in the lower electrode and the upper electrode, the resistance of the electrodes can be reduced, and a sensor having high speed response and excellent characteristics with small temperature dependence of sensitivity can be obtained.

Further, by forming the lower electrode and the upper electrode from the high-concentration impurity diffusion layer, the sacrifice film is etched to form a pressure reference chamber (pressure introduction chamber), so that resistance to an etchant used is improved. You can have. For this reason, it is also possible to prevent the electrodes from being eroded during the etching of the sacrificial film and causing variations in capacitance.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic plan configuration of a capacitance type pressure sensor according to the present invention.

FIG. 2 is a diagram showing a cross-sectional configuration of a pressure-sensitive capacitance portion and a reference capacitance portion of the capacitance-type pressure sensor along the line AB in FIG.

FIG. 3 is a diagram illustrating a cross-sectional configuration of a pressure-sensitive capacitance portion and an output terminal portion of the capacitance-type pressure sensor along a line CD in FIG. 1;

FIG. 4 is a diagram illustrating a configuration of a capacitance detection circuit.

FIG. 5 is a graph showing the relationship between the thickness of a thermal stress relaxation film and the thermal stress of a movable diaphragm.

FIG. 6 is a diagram illustrating a cross-sectional configuration of a capacitance-type pressure sensor according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a planar configuration of a capacitance type pressure sensor according to Embodiment 3 of the present invention.

FIG. 8 is a diagram showing a planar configuration of a capacitance type pressure sensor according to a fourth embodiment of the present invention.

FIG. 9 is a diagram showing a relationship between a resistance value of a lower electrode of the capacitance type pressure sensor according to the present invention and a temperature coefficient of sensitivity of the sensor.

FIG. 10 is a diagram showing the relationship between the resistance value of the upper electrode of the capacitance type pressure sensor according to the present invention and the response frequency of the sensor.

FIG. 11 is a diagram illustrating a schematic plan configuration illustrating a capacitance-type pressure sensor according to a sixth embodiment of the present invention.

12 is a diagram illustrating a cross-sectional configuration of a pressure-sensitive capacitance portion and a reference capacitance portion of the capacitance-type pressure sensor along the line EF in FIG. 11;

13 is a diagram illustrating a cross-sectional configuration of a pressure-sensitive capacitance portion of the capacitance-type pressure sensor and an output terminal portion thereof along line GH in FIG. 11;

FIG. 14 is a diagram illustrating characteristics of a method of manufacturing a capacitance type pressure sensor according to Embodiment 6 of the present invention.

FIG. 15 is a sectional view of a conventional capacitance type pressure sensor.

[Explanation of symbols]

Reference Signs List 50 substrate, 60 first lower electrode, 70 second lower electrode, 80, 82 substrate protection film, 81 first substrate protection film opening, 83 second substrate protection film opening, 90 sacrificial film, 100 1 insulating diaphragm film, 110 first upper electrode, 120 second upper electrode, 130 second
Insulating diaphragm film, 141 first etching solution inlet, 142 second etching solution inlet, 151
First pressure introduction chamber (first pressure reference chamber), 152 second
Pressure introduction chamber, 161 first pressure introduction port (first etching liquid injection port), 162 second pressure introduction chamber (second pressure reference chamber), 170 semiconductor film (polycrystalline silicon film), 200 heat Stress relaxation film, 300 movable diaphragm, 350 immobilized membrane, 400 pressure reference chamber, 5
00 Pressure sensitive capacity part, 600 Reference capacity part.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hideya Yamadera 41 41, Yokomichi, Nagakute-cho, Aichi-gun, Aichi-gun

Claims (9)

[Claims] 1. A capacitance type pressure sensor for detecting pressure based on a capacitance change of a pressure-sensitive capacitance portion formed on a substrate, wherein the pressure-sensitive capacitance portion is formed on a first surface of the substrate. First
A lower electrode, a movable diaphragm formed above the first lower electrode with a predetermined gap from the electrode, and
A pressure reference chamber formed in a gap between the lower electrode and the movable diaphragm, wherein the movable diaphragm has a first insulating diaphragm film formed on the pressure reference chamber side, and the first insulating film. A first upper electrode formed on the diaphragm film so as to face the first lower electrode, and a second insulating diaphragm film formed on the first upper electrode; A capacitance type pressure sensor comprising: a thermal stress relaxation film formed of a material having a thermal expansion coefficient close to that of the substrate on the second insulating diaphragm film. 2. The capacitance type pressure sensor according to claim 1, wherein said thermal stress relaxation film is a silicon nitride film formed by plasma CVD. 3. The capacitance type pressure sensor according to claim 1, wherein a sacrificial film is formed on the first surface of the substrate so as to cover the pressure-sensitive capacitance portion forming region, The pressure reference chamber includes at least one first etchant inlet formed to penetrate the second insulating diaphragm film and the first insulating diaphragm film to reach the sacrificial film. Forming the sacrificial film by etching through the first etchant injection port,
In addition, the etching solution injection port is sealed by the thermal stress relaxation film. 4. The capacitance type pressure sensor according to claim 1, wherein the pressure reference chamber is constituted by a pressure introduction chamber connected to a pressure introduction port formed through the substrate. A capacitance-type pressure sensor characterized in that: 5. The capacitance-type pressure sensor according to claim 1, wherein the substrate has a reference capacitance portion in which the capacitance does not change in parallel with the pressure-sensitive capacitance portion. The reference capacitance unit is formed of a second lower electrode formed on the first surface of the substrate using the same material as the first lower electrode, and the first lower electrode formed on the second lower electrode. And the first diaphragm to face the second lower electrode.
A second upper electrode formed on the insulating diaphragm film and made of the same material as the first upper electrode, and the second insulating diaphragm film formed so as to cover the second upper electrode; And a thermal stress relieving film formed on the second insulating diaphragm film. 6. A first lower electrode, a pressure reference chamber, and a first lower electrode.
And a pressure-sensitive capacitance portion including a second insulating diaphragm film and a first upper electrode; a second lower electrode; and a reference capacitance including the first and second insulating diaphragm films and a second upper electrode. Department and
Forming the first and second lower electrodes on a first surface of the substrate; and forming the pressure-sensitive sensor on the first surface of the substrate. Forming a sacrificial film so as to cover the capacitor portion forming region; and forming a first sacrificial film on the first surface of the semiconductor substrate so as to cover the sacrificial film.
Forming an insulating diaphragm film, and forming a first upper electrode at a position on the first insulating diaphragm film facing the first lower electrode, and at the same time, forming the first insulating diaphragm film Forming a second upper electrode at a position opposing the second lower electrode, and forming a second insulating diaphragm film so as to cover the first and second upper electrodes; Forming at least one etchant injection port so as to reach the sacrificial film through the second and first insulating diaphragm films; Forming a pressure reference chamber by etching and removing the sacrificial film through a liquid injection port; and a thermal expansion coefficient of the substrate on the second insulating diaphragm film by plasma CVD. Capacitive pressure method for manufacturing a sensor which comprises a step of forming a thermal stress relieving layer using a close material. 7. The manufacturing method according to claim 6, wherein the thermal stress relieving film seals the etching solution inlet so as to maintain the pressure reference chamber at a desired pressure state. A method for manufacturing a capacitance type pressure sensor. 8. A first lower electrode, a first pressure reference chamber connected to a first pressure inlet formed through the substrate, a first and a second insulating diaphragm film, and a first pressure reference chamber.
A second pressure reference portion connected to a second pressure introduction port formed through the first and second insulating diaphragm films; A method for manufacturing a capacitance-type pressure sensor in which a chamber and a reference capacitance section including a second upper electrode are formed on the same semiconductor substrate, and wherein the first and second electrodes are formed on a first surface of the substrate. Forming a lower electrode, forming a sacrificial film in a formation region of the pressure-sensitive capacitance portion and the reference capacitance portion of the substrate, and forming a sacrificial film on the first surface of the substrate so as to cover the sacrificial film. Forming a first insulating diaphragm film; forming a first upper electrode at a position on the first insulating diaphragm film opposite to the first lower electrode, and simultaneously forming the first insulating film; A second electrode is positioned on the diaphragm film so as to face the second lower electrode. Forming an upper electrode; forming a second insulating diaphragm film so as to cover the first and second upper electrodes; and forming the second insulating diaphragm film on the substrate from a second surface side of the substrate. The first pressure reference chamber is formed so as to reach the sacrificial film at the formation position of the first pressure reference chamber.
Forming the pressure inlet, and the sacrificial film at the position where the second pressure reference chamber is formed through the second and first insulating diaphragm films disposed on the first surface side of the substrate. Forming the second pressure inlet so as to reach the first and second pressure inlets at the formation positions of the first and second pressure reference chambers using the first and second pressure inlets as an etchant inlet. Forming the first and second pressure reference chambers by removing the sacrificial film by etching; and forming a thermal stress on the second insulating diaphragm film using a material having a thermal expansion coefficient close to that of the substrate by plasma CVD. Forming a relaxation film; and a method for manufacturing a capacitance type pressure sensor. 9. The capacitance type pressure sensor according to claim 1, wherein the first and second lower electrodes have a 5 × impurity concentration in the silicon substrate. An impurity diffusion layer formed by introducing at least 10 ¹⁹ / cm ³ , wherein the first and second upper electrodes are formed of an impurity diffusion layer having an impurity introduced at 5 × 10 ¹⁹ / cm ³ or more into the silicon film; A capacitance type pressure sensor or a method for manufacturing the same.