JPH09329518A - Pressure measuring device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure measuring device, in which an extremely narrow gap between a semiconductor measuring diaphragm and a supporting substrate is realized by preventing the semiconductor measuring diaphragm from being joined with the supporting substrate by an electrostatic attraction force based on an anode junction, and its manufacturing method. SOLUTION: In this pressure measuring device in which a semiconductor substrate and a supporting substrate 28 are joined by an anode junction and measurement pressure exerted on a semiconductor measuring diaphragm 23 provided for the semiconductor substrate is detected, a junction preventing electrode 61 is provided on the surface of the supporting substrate 28, the junction preventing electrode 61 is electrically connected to a silicon substrate 22 at the time of the anode coupling between the supporting substrate 28 and the silicon substrate 22, and the measuring diaphragm and the junction preventing electrode are arranged to be at the same electric potential at the time of the anode coupling. At this time, even if the gap of the second pressure chamber between the semiconductor measuring diaphragm and the supporting substrate is narrowly formed for protection at the time when excessive pressure is exerted on the semiconductor measuring diaphragm, the danger that the semiconductor measuring diaphragm is attracted to the side of the supporting substrate by an electrostatic attraction force and joined to the supporting substrate is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prevents a semiconductor measuring diaphragm from being bonded to a supporting substrate by an electrostatic attraction force based on anodic bonding, and makes an extremely narrow gap between the semiconductor measuring diaphragm and the supporting substrate. The present invention relates to a pressure measuring device that can be realized and a manufacturing method thereof.

[0002]

2. Description of the Related Art FIG. 12 is a structural explanatory view of a conventional pressure measuring device generally used, which is shown in, for example, Japanese Patent Laid-Open No. 5-288624. In this case, the pressure measuring device is used as a sensor portion of the differential pressure measuring device. 13 is a sectional view taken along the line AA of FIG. 12, and FIG. 14 is FIG.
2 is a sectional view taken along line BB of FIG.

In the figure, reference numeral 21 is a first space consisting of a predetermined gap for forming a measurement diaphragm 23 on a silicon substrate 22.
It is a pressure chamber and consists of extremely narrow gaps. A first communication hole 24 is provided in the silicon substrate 22 and has one end communicating with the first pressure chamber 21.

Reference numeral 25 denotes a recess provided on the surface of the measurement diaphragm 23 opposite to the surface on which the first pressure chamber 21 is provided, and has a very shallow depth. Reference numeral 26 is a rising portion which is provided in the silicon substrate 22 and which communicates with the concave portion 25 and surrounds the measurement diaphragm 23 in a ring shape except for the portion of the first communication hole 24.

Reference numeral 27 denotes a concave portion 25 of the measuring diaphragm 23.
It is a strain detecting element provided on the side. Reference numeral 28 denotes a support substrate, one surface of which is connected to the surface of the silicon substrate 22 on which the recess 25 is provided and which forms the recess 25 and the second pressure chamber 29.

As shown in FIG. 15, reference numeral 31 designates a wiring made of a conductor having one end connected to the strain detecting element 27, which is formed by mixing impurities in the bonding surface of the silicon substrate 22 with the supporting substrate 28. 32 is a support substrate 28 as shown in FIG.
Is an electrode which is provided on the side of the joint surface with the silicon substrate 22 and whose one end is connected to the wiring 31.

Reference numeral 33 denotes a groove portion provided near the electrode 32 of the silicon substrate 22, as shown in FIG. Groove 3
3 imparts an appropriate spring property to the contact portion of the silicon substrate 22 with the electrode 32, and stably holds the contact between the electrode 32 and the wiring 31.

As shown in FIG. 16, 41 is provided on the silicon substrate 22 so that dust in the fluid as a pressure medium is
This is a filter portion that prevents the pressure chamber 21 or the second pressure chamber 29 from being mixed. In this case, two pieces are provided.

By forming the gap d of the filter section 41 sufficiently small by a semiconductor process, dust is prevented from entering. That is, now, the gap d of the filter portion 41 is configured to satisfy d ≦ A−B, where A is the gap distance between the first pressure chambers 21 and B is the displacement amount of the measurement diaphragm 23. .

One side of the filter portion 41 has a first communicating hole 2
It is connected to 4. The other side of the filter unit 41 is the second
It communicates with the second pressure chamber 29 through the communication hole 42.
Reference numeral 51 is a first pressure guide hole that is provided on the support substrate 28, communicates with one side of the filter portion 41, and has the other end open to the atmosphere.

Reference numeral 52 is a second pressure guide hole which is provided on the support substrate 28, communicates with the other side of the filter portion 41, and has the other end open to the atmosphere. Reference numeral 53 is a projecting portion connected to the rising portion 26. When a high pressure is applied to the overhanging portion 53, the overhanging portion 53 receives the high pressure and the silicon substrate 2
It is configured so that a large stress is not generated in the joint portion between 2 and the supporting substrate 28.

In the above structure, the high pressure side measured pressure is applied to the first pressure chamber 21 and the low pressure side measured pressure is applied to the second pressure chamber 29. As a result, the silicon measuring diaphragm 23 is distorted in accordance with the pressure difference between the high pressure side and the low pressure side, and the amount of this distortion is electrically detected by the strain detecting element 27, and a signal is transmitted to the outside via the wiring 31 and the electrode 32. Taken out,
The differential pressure is measured.

When an overpressure is applied to the first pressure chamber 21, the measuring diaphragm 23 is moved to the second pressure chamber 29.
Backed by walls. On the other hand, the second pressure chamber 2
If an overpressure is applied to 9, the measurement diaphragm 2
3 is backed up by the wall of the first pressure chamber 21.

Such a device is manufactured as shown in FIGS. (1) As shown in FIG. 17, silicon 104 is etched by RIE etching on a required portion 102 of an SOI wafer 101, and silicon oxide 10 is etched by a hydrofluoric acid-based etching solution.
3 is etched, silicon oxide 103 and silicon 1
04 is etched. In this case, silicon oxide 10
3 has a thickness of about 1 μm, and silicon 104 has a thickness of about 0.5 μ.
m, the thickness of the silicon of the substrate is about 600 μm. FIG.
FIG. 18 is a plan view of FIG.

(2) As shown in FIG. 19, the SOI wafer 1
An epitaxial growth layer 105 is grown on the surface of 01. In this case, the thickness of the epitaxial growth layer 105 is about 70 μm.

(3) As shown in FIG. 20, the surface of the epitaxial growth layer 105 is processed into a mirror surface by polishing. In this case, about 50 μm is removed. This step determines the thickness of the measurement diaphragm 23. (4) As shown in FIG. 21, the epitaxial growth layer 105
The surface of is etched by RIE etching to form the recess 106. The recess 106 determines the gap of the second pressure chamber 29 that determines the movable range of the measurement diaphragm 23 on one side.

(5) As shown in FIG. 22, embedded,
A ring-shaped groove 107 for etching the silicon oxide 103 is formed by RIE etching or etching with potassium hydroxide.

(6) As shown in FIG. 23, the silicon oxide 103 is etched with an aqueous solution of hydrogen fluoride or hydrogen fluoride gas. (7) As shown in FIG. 24, the silicon substrate 22 is anodically bonded to the support substrate 28 of Pyrex glass.

As a result, (1) since the outside of the differential pressure sensor may be atmospheric pressure, no special pressure vessel is required. (2) A high withstand voltage hermetically sealed terminal for taking out an electric signal to the outside is unnecessary.

(3) Since the silicon wafer 101 can be processed from one side, the forming process becomes simple. (4) Since the sensor itself has an overpressure protection mechanism,
The overpressure protection mechanism is no longer necessary.

(5) Since the measuring diaphragm 23 is surrounded by the first pressure chamber 21, the second pressure chamber 29 and the rising portion 26, it is possible to effectively prevent the disturbance strain from being transmitted to the measuring diaphragm 23. Thus, a semiconductor differential pressure measuring device having good noise resistance can be obtained.

[0022]

However, in such a pressure measuring device, the silicon substrate 22 and the supporting substrate 28 are anodically bonded. Therefore, for protection when an excessive pressure is applied to the semiconductor measurement diaphragm 23,
The gap of the second pressure chamber 29 between the semiconductor measuring diaphragm 23 and the support substrate 28 is configured to be narrow. For example, it is about submicron.

As described above, when the gap becomes narrower, as shown in FIG.
As shown in FIG. 5, the semiconductor measurement diaphragm 23 is attracted to the support substrate 28 side by the electrostatic attraction force, and the semiconductor measurement diaphragm 23 is bonded to the support substrate 28. Therefore, the yield is poor and the manufacturing cost is high.

The present invention solves this problem. An object of the present invention is to prevent the semiconductor measuring diaphragm from being bonded to a supporting substrate by an electrostatic attraction force based on anodic bonding, and to ensure an extremely narrow gap between the semiconductor measuring diaphragm and the supporting substrate. A pressure measuring device and a manufacturing method thereof are provided.

[0025]

In order to achieve this object, the present invention provides (1) a semiconductor substrate and a supporting substrate are anodically bonded to each other to detect a measurement pressure applied to a semiconductor measuring diaphragm provided on the semiconductor substrate. In the pressure measuring device, a recess is provided on one surface of the semiconductor substrate to form the semiconductor measuring diaphragm on the semiconductor substrate, and one surface is anodically bonded to the one surface of the semiconductor substrate to form a pressure chamber with the recess and the semiconductor. A support substrate that is backed up to protect the semiconductor measurement diaphragm when an overpressure is applied to the measurement diaphragm, and an electrical connection with the semiconductor substrate provided on the one surface of the support substrate so as to face the semiconductor measurement diaphragm. Connected to ensure the same potential to prevent the semiconductor measuring diaphragm from being bonded to the supporting substrate by electrostatic attraction. A pressure measuring device, comprising: (2) In a pressure measuring device in which a semiconductor substrate and a supporting substrate are anodic-bonded to each other and a measuring pressure applied to a semiconductor measuring diaphragm provided on the semiconductor substrate is detected, the semiconductor measuring diaphragm is formed on a silicon substrate and the semiconductor measuring diaphragm is formed. A first pressure chamber having a predetermined narrow gap for backing up when an excessive pressure is applied to the semiconductor measurement diaphragm and protecting the semiconductor measurement diaphragm; and a surface of the measurement diaphragm opposite to the surface on which the first pressure chamber is provided. One surface is joined to the concave portion provided on the semiconductor substrate and the concave surface of the silicon substrate to form a second pressure chamber with the concave portion, and an excessive pressure is applied to the semiconductor measuring diaphragm. In some cases, the semiconductor substrate is backed up to protect the semiconductor measurement diaphragm, and the semiconductor substrate is measured on the one surface of the support substrate. And a bonding prevention electrode that is provided so as to face the diaphragm and is electrically connected to the semiconductor substrate to secure the same potential to prevent the semiconductor measurement diaphragm from being bonded to the support substrate by an electrostatic attraction force. A pressure measuring device characterized in that (3) A method of manufacturing a pressure measuring device, in which a semiconductor substrate and a supporting substrate are anodically bonded to each other, and a measuring pressure applied to a semiconductor measuring diaphragm provided on the semiconductor substrate is detected. Device manufacturing method. (A) A required portion etching step of etching silicon oxide and silicon at required portions of the SOI wafer. (B) An epitaxial growth step of growing an epitaxial growth layer on the surface of the SOI wafer. (C) A polishing step of polishing the surface of the epitaxial growth layer into a mirror surface. (D) A recess forming step of etching the surface of the epitaxial growth layer to form a recess and also forming a strain gauge. (E) A groove forming step of forming a ring-shaped groove for etching the buried silicon oxide. (F) A silicon oxide etching step of etching the silicon oxide. (G) A bonding prevention electrode forming step of forming a bonding prevention electrode on a required portion of the surface of the supporting substrate. (H) Anodic bonding step of anodic bonding the silicon substrate 22 to the supporting substrate. It was adopted.

[0026]

In the above structure, the bonding prevention electrode is provided on the surface of the supporting substrate, and the bonding prevention electrode is electrically connected to the silicon substrate during anodic bonding between the supporting substrate and the silicon substrate. The measurement diaphragm and the bonding prevention electrode have the same potential.

Therefore, even if the gap of the second pressure chamber between the semiconductor measuring diaphragm and the supporting substrate is narrowed for protection when an excessive pressure is applied to the semiconductor measuring diaphragm,
There is no fear that the semiconductor measuring diaphragm is attracted to the supporting substrate side by the electrostatic attraction force and the semiconductor measuring diaphragm is bonded to the supporting substrate. Hereinafter, detailed description will be given based on examples.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of the essential structure of an embodiment of the present invention, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG.
It is a -B sectional view. In the figure, the same symbols as those in FIG. 12 represent the same functions. Hereinafter, only differences from FIG. 12 will be described.

Reference numeral 61 is provided on one surface of the support substrate 28 so as to face the semiconductor measurement diaphragm 23.
2 is a bonding prevention electrode that is electrically connected to 2 and secures the same potential to prevent the semiconductor measurement diaphragm 23 from being bonded to the support substrate 28 by an electrostatic attraction force.

In the above structure, the bonding prevention electrode 61 is provided on the surface of the support substrate 28, and the bonding prevention electrode 61 is electrically connected to the silicon substrate 22 at the time of anodic bonding between the support substrate 28 and the silicon substrate 22. Therefore, at the time of anodic bonding, the measurement diaphragm 23 and the bonding prevention electrode 61 have the same potential.

Therefore, even if the gap of the second pressure chamber 29 between the semiconductor measuring diaphragm 23 and the supporting substrate 28 is made narrower for protection when an excessive pressure is applied to the semiconductor measuring diaphragm 23, the semiconductor measuring diaphragm 23 is formed. 23, there is no fear that the semiconductor measurement diaphragm 23 will be attracted to the support substrate 28 side by the electrostatic attraction force and will be bonded to the support substrate 28.

Such a device is manufactured as shown in FIGS. In this case, the portion used as the sensor portion of the differential pressure measuring device shown in the conventional example of FIG. 12 is also manufactured in parallel, but the formation of the sensor portion of the differential pressure measuring device is shown in FIG. Since the conventional example has already been described, it will not be described here.

(A) As shown in FIG. 4, the SOI wafer 20
The required portion 202 of No. 1 is etched with the silicon 204 by RIE etching, and the silicon oxide 203 is etched with the hydrofluoric acid-based etching solution,
And silicon 204 is etched. In this case, the thickness of the silicon oxide 203 is about 1 μm, the thickness of the silicon 204 is about 0.5 μm, and the thickness of the silicon of the substrate is about 600 μm.

(B) As shown in FIG. 5, the SOI wafer 20
An epitaxial growth layer 205 is grown on the surface of 1.
In this case, the thickness of the epitaxial growth layer 205 is about 7
0 μm.

(C) As shown in FIG. 6, the surface of the epitaxial growth layer 205 is polished to a mirror surface. In this case, about 50 μm is removed. This step determines the thickness of the measurement diaphragm 23.

(D) As shown in FIG. 7, the surface of the epitaxial growth layer 205 is etched by RIE etching to form a recess 206. The recess 206 determines the gap of the second pressure chamber 29 that determines the movable range of the measurement diaphragm 23 on one side. Then, the strain gauge 207 is formed at a position corresponding to the measurement diaphragm 23.

(E) As shown in FIG. 8, an embedded ring-shaped groove 2 for etching the silicon oxide 203.
08 is formed by RIE etching or potassium hydroxide etching.

(F) As shown in FIG. 9, the silicon oxide 203 is etched with an aqueous solution of hydrogen fluoride or hydrogen fluoride gas.

(G) As shown in FIG. 10, Ti / Pt is formed on the surface of the supporting substrate 209 made of Pyrex glass at a required position.
The electrode 211 is formed. In this case, photolithography is used to form the pattern. This pattern is formed in a portion facing the measurement diaphragm 23 and a portion corresponding to the wiring electrode 32.

Here, the electrode 211 in the portion facing the measurement diaphragm 23 is used as the bonding prevention electrode 61, and the electrode 211 in the portion corresponding to the wiring electrode 32 is used as the wiring electrode 32. (H) As shown in FIG. 11, the silicon substrate 22 is anodically bonded to the support substrate 28 of Pyrex glass.

As a result, the bonding prevention electrode 61 is provided on the surface of the support substrate 28, and the support substrate 28 and the silicon substrate 2 are provided.
Since the bonding prevention electrode 61 is electrically connected to the silicon substrate 22 at the time of anodic bonding with 2, the measurement diaphragm 23 and the bonding prevention electrode 61 can have the same potential at the time of anodic bonding.

Therefore, even if the gap of the second pressure chamber 29 between the semiconductor measuring diaphragm 23 and the supporting substrate 28 is made narrow for protection when an excessive pressure is applied to the semiconductor measuring diaphragm 23, the semiconductor measuring diaphragm is formed. It is possible to obtain the pressure measuring device and its manufacturing method in which 23 is attracted to the supporting substrate 28 side by the electrostatic attraction force and the semiconductor measuring diaphragm 23 is not bonded to the supporting substrate 28.

Thus, the pressure measuring device and the manufacturing method thereof can be obtained, which can improve the manufacturing yield and reduce the manufacturing cost. That is, it is possible to make the gap of the second pressure chamber 29 between the semiconductor measurement diaphragm 23 and the support substrate 28 extremely narrow.

[0044]

As described in detail above, according to the present invention, the bonding prevention electrode is provided on the surface of the supporting substrate, and the bonding prevention electrode is bonded to the silicon substrate at the time of anodic bonding between the supporting substrate and the silicon substrate. Since they are electrically connected, the measurement diaphragm and the bonding prevention electrode can be made to have the same potential during anodic bonding.

Therefore, even if the gap of the second pressure chamber between the semiconductor measuring diaphragm and the supporting substrate is made narrow for protection when an excessive pressure is applied to the semiconductor measuring diaphragm,
The semiconductor measuring diaphragm is attracted to the supporting substrate side by the electrostatic attraction force, and the pressure measuring device and the manufacturing method thereof, in which the semiconductor measuring diaphragm is not bonded to the supporting substrate, can be obtained.

Thus, the pressure measuring device and the manufacturing method thereof, which can improve the manufacturing yield and reduce the manufacturing cost, can be obtained. That is, it is possible to make the gap of the second pressure chamber between the semiconductor measurement diaphragm and the support substrate extremely narrow.

Therefore, according to the present invention, the semiconductor measuring diaphragm is prevented from being bonded to the supporting substrate by the electrostatic attraction force based on the anodic bonding, and an extremely narrow gap is provided between the semiconductor measuring diaphragm and the supporting substrate. It is possible to realize the pressure measuring device and its manufacturing method that can be realized and secured.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a main part configuration of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is an explanatory diagram of a required portion etching process of FIG. 1.

5 is an explanatory diagram of the epitaxial growth process of FIG.

FIG. 6 is an explanatory diagram of a polishing process of FIG.

FIG. 7 is an explanatory view of a recess forming step of FIG.

8 is an explanatory view of the groove forming process of FIG.

9 is an explanatory diagram of the silicon oxide etching step of FIG. 1. FIG.

FIG. 10 is an explanatory diagram of a process for forming a bonding prevention electrode in FIG.

FIG. 11 is an explanatory diagram of the anodic bonding process of FIG. 1.

FIG. 12 is an explanatory diagram of a configuration of a conventional example generally used from the prior art.

13 is a sectional view taken along line AA of FIG.

14 is a cross-sectional view taken along the line BB of FIG.

FIG. 15 is a detailed explanatory diagram of a main part of FIG. 12;

16 is a detailed explanatory diagram of a main part of FIG. 12;

17 is an explanatory diagram of an etching process of FIG.

FIG. 18 is a plan view of FIG.

FIG. 19 is an explanatory diagram of the epitaxial growth layer forming process of FIG.

20 is an explanatory diagram of the polishing process of FIG.

FIG. 21 is an explanatory view of a recess forming step of FIG.

22 is an explanatory diagram of the groove forming process of FIG.

23 is an explanatory diagram of the silicon oxide etching step of FIG.

FIG. 24 is an explanatory diagram of the anodic bonding process of FIG. 12.

25 is an explanatory diagram of the operation of FIG.

[Explanation of symbols]

 21 First Pressure Chamber 22 Silicon Substrate 23 Measuring Diaphragm 24 First Communication Hole 25 Recessed Section 26 Rising Part 27 Strain Detection Element 28 Support Substrate 29 Second Pressure Chamber 31 Wiring 32 Electrode 41 Filter Section 42 Second Communication Hole 51 First Conductive Pressure Hole 52 Second pressure guiding hole 53 Overhanging portion 61 Bonding prevention electrode 101 SOI wafer 102 Required part 103 Silicon oxide 104 Silicon 105 Epitaxial growth layer 106 Recess 107 Groove hole 201 SOI wafer 202 Required part 203 Silicon oxide 204 Silicon 205 Epitaxial growth layer 206 Recess 207 Strain gauge 208 Groove 209 Pyrex glass 211 Ti / Pt electrode

Claims (3)

[Claims] 1. A semiconductor substrate and a supporting substrate are anodically bonded,
A pressure measuring device for detecting a measurement pressure applied to a semiconductor measuring diaphragm provided on a semiconductor substrate, comprising: a concave portion provided on one surface of the semiconductor substrate to form the semiconductor measuring diaphragm; and one surface on the one surface of the semiconductor substrate. Is anodically bonded to form the recess and the pressure chamber, and a support substrate that is backed up to protect the semiconductor measurement diaphragm when an overpressure is applied to the semiconductor measurement diaphragm; and the semiconductor on the one surface of the support substrate. A bonding prevention electrode that is provided so as to face the measurement diaphragm and is electrically connected to the semiconductor substrate to secure the same potential to prevent the semiconductor measurement diaphragm from being bonded to the support substrate by an electrostatic attraction force. A pressure measuring device characterized by being provided. 2. A semiconductor substrate and a supporting substrate are anodically bonded,
In a pressure measuring device for detecting a measurement pressure applied to a semiconductor measuring diaphragm provided on a semiconductor substrate, the semiconductor measuring diaphragm is formed on a silicon substrate and the semiconductor measuring diaphragm is backed up when an excessive pressure is applied to the semiconductor measuring diaphragm. A first pressure chamber having a predetermined narrow gap for protecting the semiconductor measurement diaphragm; a recess provided on the semiconductor substrate on a surface of the measurement diaphragm opposite to a surface on which the first pressure chamber is provided; One surface is joined to the surface of the substrate on which the recess is provided to form the recess and the second pressure chamber, and the semiconductor measurement diaphragm is backed up to protect the semiconductor measurement diaphragm when an overpressure is applied to the semiconductor measurement diaphragm. A substrate and the semiconductor provided on the one surface of the supporting substrate so as to face the semiconductor measurement diaphragm. A pressure measuring device comprising: a bonding prevention electrode that is electrically connected to the substrate to secure the same potential to prevent the semiconductor measuring diaphragm from being bonded to the supporting substrate by an electrostatic attraction force. . 3. A semiconductor substrate and a supporting substrate are anodically bonded,
A method of manufacturing a pressure measuring device for detecting a measurement pressure applied to a semiconductor measuring diaphragm provided on a semiconductor substrate, comprising the following steps. (A) A required portion etching step of etching silicon oxide and silicon at required portions of the SOI wafer. (B) An epitaxial growth step of growing an epitaxial growth layer on the surface of the SOI wafer. (C) A polishing step of polishing the surface of the epitaxial growth layer into a mirror surface. (D) A recess forming step of etching the surface of the epitaxial growth layer to form a recess and also forming a strain gauge. (E) A groove forming step of forming a ring-shaped groove for etching the buried silicon oxide. (F) A silicon oxide etching step of etching the silicon oxide. (G) A bonding prevention electrode forming step of forming a bonding prevention electrode on a required portion of the surface of the supporting substrate. (H) Anodic bonding step of anodic bonding the silicon substrate 22 to the supporting substrate.