JPH09196786A - Semiconductor capacitance-type pressure sensor and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sensor whose temperature characteristic is good by a method wherein an insulating film is formed on a face side opposite to an electrode part at a diaphragm part on a silicon substrate and another insulating film which is equivalent to the insulating film is formed on a face on its opposite side. SOLUTION: A lower-side composite insulating film 1 is formed on a lower-side face opposite to an electrode part 17 at a diaphragm part 14 on a silicon substrate 15, and an upper-side composite insulating film 5 is formed on an opposite side face. The insulating films 1, 5 are composed respectively of oxide films 2, 6 and of nitride films 3, 7, their film thickness is selected respectively in a range of about 1000 to 3000Å, and the films are formed by a CVD method. When the diaphragm part 14 on the substrate 15 is bent by a pressure difference, a capacitance value between the diaphragm part and the electrode part 17 is changed, and a change in the capacitance value is output to a processing circuit at a later stage. By this method, a stress is applied to the diaphragm part 14 from the upper side and the lower side by the insulating films 1, 5, and it is possible to prevent the diaphragm part 14 from being deformed due to the stress and due to a temperature change.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor capacitive pressure sensor used for detecting various pressures in various industrial equipments, home electric appliances, automobiles, etc., and in particular, measures for improving temperature characteristics are taken, Regarding a pressure sensor. More specifically, the present invention relates to a holding structure of a detection element portion of a semiconductor capacitive pressure sensor used for pressure detection in automobiles, pressure detection in home appliances and the like.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view showing an example of a conventional semiconductor pressure sensor. Referring to FIG. 2, in the semiconductor pressure sensor 50, the detection element portion 51 is provided on the lower outer case 12 of the second outer case that forms the outer shell of the sensor together with the upper case 11 as the first outer case. The detector element 51 is joined by an adhesive 13, and a silicon substrate 15 having a diaphragm portion 14 that is deformed by the pressure to be measured and an insulating substrate 16 are joined by means such as electrostatic joining.

Here, an electrode portion 17 which is one of the electrodes of the air condenser portion is formed on the insulating substrate 16 and a through hole 18 for opening the gauge pressure is formed.

Further, the diaphragm portion 14 is provided on the lower side surface of the diaphragm portion 14 (the side facing the electrode portion 17).
An insulating film 52 or the like is formed as a measure for insulation between the electrode 17 and the electrode 17.

The conventional example shown in FIG. 1 is an example of an electrostatic capacity method for pressure detection, and the diaphragm portion 14 of the silicon substrate 15 bends in response to a pressure difference (P = P ₁ -P ₂ ), so that the diaphragm portion is bent. The capacitance value of the air capacitor formed between the electrode 14 and the electrode portion 17 changes, and this change in capacitance is used as the output of a processing circuit (capacitance-frequency conversion circuit) (not shown) in the subsequent stage.

[0006]

The above-mentioned conventional method has the following problems.

First, first, the insulating substrate 16 and the adhesive 1
3. When the ambient temperature changes due to a slight difference in the coefficient of linear expansion between the lower cases 12, mechanical strain in the plane direction occurs and the temperature coefficient of capacitance cannot be completely zero.

A second problem is that the oxide film 52, which is an insulating film below the diaphragm portion 14 of the silicon substrate 15, is formed.
In general, a silicon oxide film or the like is used, but stress (thermal stress) is applied to the diaphragm portion 14 of the silicon substrate 15 due to a temperature change due to a difference in linear expansion coefficient between the substrate silicon and the oxide film 52. It takes.

A third problem is that the diaphragm portion 14 is affected by the temperature change in the same manner as the cause of the first problem.
Is deformed, and the temperature characteristics are deteriorated.

Therefore, a technical object of the present invention is to provide a highly accurate semiconductor capacitive pressure sensor having a good temperature characteristic in which the deformation of the diaphragm portion due to the stress and the corrected temperature characteristic are excellent, and a manufacturing method thereof.

[0011]

In order to solve the above-mentioned problems, in the semiconductor capacitive pressure sensor of the present invention, a silicon substrate having a diaphragm portion which is deformed from the pressure to be measured,
In a semiconductor capacitive pressure sensor having a detection element portion formed by joining an insulating substrate having an electrode portion formed thereon, a first outer case and a second outer case, the diaphragm portion on the silicon substrate. At least one first insulating film is formed on the surface side facing the electrode portion, and at least one second insulating film equivalent to the insulating film is formed on the opposite side surface of the diaphragm portion. Is characterized in that the insulating film is formed.

Further, in the semiconductor capacitive pressure sensor of the present invention, in the semiconductor capacitive pressure sensor, the first or second insulating film on the diaphragm portion is a silicon oxide film (SiO ₂ ) and a nitride film. Silicon film (Si ₃ N ₄ )
And a composite film formed by CVD.
It is characterized in that it is formed by at least one of the method, the sputtering method, and the thermal oxidation method.

Further, in the method of manufacturing a semiconductor capacitive pressure sensor of the present invention, a silicon substrate having a diaphragm portion which is deformed by a pressure to be measured and an insulating substrate having an electrode portion are bonded to each other to form a detection element portion. In the method of manufacturing a semiconductor capacitance type pressure sensor according to the above, a CVD method is provided on a surface side of the diaphragm section on the silicon substrate facing the electrode section,
The first insulating film is formed by at least one of a sputter method and a thermal oxidation method, and a second insulating film equivalent to the insulating film is formed on the opposite side of the diaphragm portion to the CV.
The method is characterized in that the second insulating film is formed by at least one of the D method, the sputtering method, and the thermal oxidation method.

Furthermore, in the method of manufacturing a semiconductor capacitive pressure sensor according to the present invention, in the method of manufacturing a semiconductor capacitive pressure sensor, the first or second insulating film includes a silicon oxide film and a silicon nitride film. It is characterized by being a composite membrane.

[0015]

Embodiments of the present invention will be described below.

FIG. 1 is a sectional view showing a semiconductor capacitive pressure sensor according to an embodiment of the present invention. As shown in FIG. 1, a lower outer case 1 of a second outer case that forms an outer shell of a sensor together with an upper case 11 as a first outer case.
2, the detection element portion 10 is bonded by an adhesive 13, and the detection element portion 51 has a silicon substrate 15 having a diaphragm portion 14 that is deformed by the measured pressure.
The insulating substrate 16 and the insulating substrate 16 are joined together by means such as electrostatic joining. Further, the electrode terminal 20 is drawn out from the inside of the case through the lower outer case 12 and one side of the lower case 12. There are a pair of these electrode terminals, and they are respectively connected to one end of the electrode 17 and the silicon substrate by a bonding wire (not shown).

A lower composite insulating film 1 is formed as a first insulating film on the lower side surface of the diaphragm portion 14 facing the electrode portion 17. The lower composite insulating film 1 is an oxide film (S
It is composed of iO ₂ ) 1 and a nitride film (Si ₃ N ₄ ) 2, and the film thickness of each is appropriately selected from the range of 1000 angstroms to 3000 angstroms.

On the other hand, in the embodiment of the present invention, unlike the conventional example shown in FIG. 2, an oxide film as a second insulating film similar to the first insulating film is formed on the opposite side surface of the diaphragm portion 14. An upper composite insulating film 5 (composite thereof) composed of (SiO ₂ ) 6 and nitride film (Si ₃ N ₄ ) 7 is formed.

These upper and lower composite insulating films 1, 5
Is formed by the chemical vapor deposition method (CVD method) as follows.

First, the silicon substrate 15 is placed in a reaction tube, and a mixed gas of monosilane (SiH ₄ ) and oxygen (O ₂ ) is flown into the reaction tube as a source gas, and the reaction tube temperature is 300 to 400. The temperature was raised to ℃ and the mixed gas was thermally decomposed to form the oxide film 1 and the oxide film 6.

Next, a mixed gas of dichlorosilane (SiH ₂ Cl ₂ ) and ammonia (NH ₃ ) was flown into the reaction tube as a raw material gas and heated to 700 to 750 ° C. to form an oxide film. The nitride film 2 and the nitride film 6 were formed on the oxide film 1 and the oxide film 6, respectively.

The semiconductor capacitive pressure sensor shown in FIG. 1 performs the same detection operation as shown in FIG. That is, when the diaphragm portion 14 of the silicon substrate 15 is bent due to the pressure difference (P = P ₁ -P ₂ ), the capacitance value of the air capacitor formed between the diaphragm portion 14 and the electrode portion 17 is changed. This change in capacitance is used as the output of a processing circuit (capacitance-frequency conversion circuit) (not shown) in the subsequent stage.

However, in the semiconductor capacitive pressure sensor according to the embodiment of the present invention, as described above, the diaphragm portion 14 is formed by the upper and lower composite insulating films 1 and 5.
Is applied with stress from the upper and lower composite insulating films 1 and 5 from the upper side and the lower side, and apparently the diaphragm portion 1
4 and the deformation due to temperature change are prevented. Therefore, the deformation of the diaphragm portion 14 as in the conventional example is prevented, and a highly accurate semiconductor capacitive pressure sensor can be provided.

[0024]

As described above, the diaphragm portion of the silicon substrate of the pressure sensor of the present invention is also subjected to the stress from the first and second insulating films having the same film quality on both surfaces, and as a result,
The deformation of the diaphragm hardly occurs with respect to the temperature change. Therefore, it is possible to provide a highly accurate semiconductor capacitive pressure sensor having a good temperature characteristic, in which the deformation of the diaphragm due to the stress is corrected, and a manufacturing method thereof. it can.

[Brief description of drawings]

FIG. 1 is a sectional view showing a semiconductor capacitive pressure sensor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an example of a conventional semiconductor pressure sensor.

[Explanation of symbols]

 1 Lower Composite Insulating Film 2,6,52 Oxide Film 3,7 Nitride Film 5 Upper Composite Insulating Film 10,51 Detection Element Section 11 Upper Case 12 Lower Case 14 Diaphragm Section 15 Silicon Substrate 16 Insulating Substrate 17 Electrode Section 19 Pressure Inlet port 20 Electrode terminal 50 Semiconductor capacitive pressure sensor

Claims (4)

[Claims] 1. A detection element portion formed by joining a silicon substrate having a diaphragm portion that is deformed by a pressure to be measured and an insulating substrate having an electrode portion, a first outer case, and a second outer portion. In a semiconductor capacitive pressure sensor having a case, at least one layer of a first insulating film is formed on the surface of the diaphragm portion on the silicon substrate facing the electrode portion, and the diaphragm portion. of,
A semiconductor capacitive pressure sensor characterized in that at least one layer of a second insulating film equivalent to the first insulating film is formed on the opposite side surface. 2. The semiconductor capacitive pressure sensor according to claim 1, wherein the first or second on the diaphragm portion.
Is composed of a composite film of a silicon oxide film (SiO ₂ ) and a silicon nitride film (Si ₃ N ₄ ). The composite film is formed by a CVD method, a sputtering method, or a thermal oxidation method. A semiconductor capacitive pressure sensor characterized by being formed by at least one of these methods. 3. A method of manufacturing a semiconductor capacitance type pressure sensor, comprising: forming a detection element unit by joining a silicon substrate having a diaphragm portion that is deformed by a pressure to be measured and an insulating substrate having an electrode portion to each other. A CVD method is provided on a surface side of the diaphragm portion facing the electrode portion on the substrate,
The first insulating film is formed by at least one of a sputter method and a thermal oxidation method, and a second insulating film equivalent to the insulating film is formed on the opposite side of the diaphragm portion to the CV.
A method of manufacturing a semiconductor capacitive pressure sensor, characterized in that the second insulating film is formed by at least one of the D method, the sputtering method and the thermal oxidation method. 4. The method of manufacturing a semiconductor capacitance type pressure sensor according to claim 3, wherein the first or second insulating film is a composite film including a silicon oxide film and a silicon nitride film. Manufacturing method of semiconductor capacitive pressure sensor.