JPH10270714A - Manufacture of semiconductor inertia sensor - Google Patents

Manufacture of semiconductor inertia sensor

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Publication number
JPH10270714A
JPH10270714A JP9072956A JP7295697A JPH10270714A JP H10270714 A JPH10270714 A JP H10270714A JP 9072956 A JP9072956 A JP 9072956A JP 7295697 A JP7295697 A JP 7295697A JP H10270714 A JPH10270714 A JP H10270714A
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Japan
Prior art keywords
film
crystal silicon
layer
silicon wafer
movable electrode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
JP9072956A
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Japanese (ja)
Inventor
Kensuke Muraishi
Hiroshi Shibatani
賢介 村石
博志 柴谷
Original Assignee
Mitsubishi Materials Corp
三菱マテリアル株式会社
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Application filed by Mitsubishi Materials Corp, 三菱マテリアル株式会社 filed Critical Mitsubishi Materials Corp
Priority to JP9072956A priority Critical patent/JPH10270714A/en
Publication of JPH10270714A publication Critical patent/JPH10270714A/en
Withdrawn legal-status Critical Current

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Abstract

[PROBLEMS] To provide a high-sensitivity, high-accuracy semiconductor inertial sensor which does not require laser processing, is suitable for mass production, has low parasitic capacitance, and is excellent in gap formation between electrodes. A stacked body including a second single-crystal silicon layer, a second oxide film, a first single-crystal silicon layer, a first oxide film, and a second silicon wafer is formed.
The second single crystal silicon layer and the second oxide film are selectively etched away to form a spacer layer 24 including the second single crystal silicon layer and the second oxide film. The first single crystal silicon layer is selectively etched away to have a second silicon wafer, a first oxide film, a movable electrode 26 made of single crystal silicon, fixed electrodes 27 and 28 made of single crystal silicon, and a spacer layer. The structure 25 is formed. The structure is bonded to the glass substrate 10 via the spacer layer 24. The second silicon wafer and the first oxide film are sequentially removed by etching to obtain the semiconductor inertial sensor 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor inertial sensor suitable for a capacitance type acceleration sensor, angular velocity sensor and the like.

[0002]

2. Description of the Related Art Conventionally, as this kind of semiconductor inertial sensor, a resonance angular velocity sensor having a structure of a glass substrate and single crystal silicon has been proposed (M. Hashimoto et al.,
"Silicon Resonant Angular Rate Sensor", Techinica
l Digest of the 12th Sensor Symposium, pp.163-166
(1994)). This sensor has a movable electrode with a tuning fork structure that floats on both sides with a torsion bar. This movable electrode is excited by electromagnetic drive. When the angular velocity acts, a Coriolis force is generated on the movable electrode, and the movable electrode causes torsional vibration around the torsion bar to resonate. The sensor detects an angular velocity that acts due to a change in capacitance between the movable electrode and the detection electrode due to resonance of the movable electrode. When this sensor is manufactured, a structure such as a movable electrode portion is manufactured by etching a single crystal silicon substrate having a thickness of about 200 μm and having a crystal orientation of (110) perpendicular to the substrate surface. In order to vertically etch this relatively thick silicon substrate, anisotropic dry etching using SF 6 gas is performed, or after drilling a YAG laser at the corner of the base of the torsion bar to the movable electrode portion, ,
Wet etching is performed with KOH or the like. The etched silicon substrate is integrated with the glass substrate by anodic bonding.

As another semiconductor inertial sensor, after a sacrificial layer is patterned on a silicon substrate by etching,
A micro-gyro (K. Tanaka et al., "A
micromachined vibrating gyroscope ", Sensors and A
ctuators A 50, pp. 111-115 (1995)). This microgyro has a structure using a so-called surface micromachining technology. In particular,
Forming a detection electrode by impurity diffusion on a silicon substrate,
After forming and patterning a phosphate glass film serving as a sacrificial layer thereon, a polysilicon film is formed, and a process such as vertical etching is performed to form a structure. Finally, by removing the sacrificial layer by etching, the movable electrode portion is cut off to create a gap with respect to the detection electrode, and the movable electrode is brought into a floating state.

As another semiconductor inertial sensor, a gyroscope having a structure of a glass substrate and single crystal silicon has been proposed (J. Bernstein et al., "A Microma
chined Comb-Drive Tuning Fork Rate Gyroscope ", IEE
E MEMS '93 Proceeding, pp.143-148 (1993)). This gyroscope has a glass substrate on which a detection electrode is formed,
After the etching, high-concentration boron diffusion is performed to form a movable electrode, a fixed electrode, etc., on a single-crystal silicon substrate, where the boron-diffused portion is used as a bonding surface, and further, the silicon substrate portion where boron is not diffused. Is removed by etching.

[0005]

The above-mentioned conventional techniques for manufacturing a sensor have the following disadvantages. In the method of manufacturing the resonance angular velocity sensor described above, the silicon active portion which should be a structure floating with respect to the glass substrate sometimes adheres to the glass substrate due to electrostatic attraction during anodic bonding and does not become a movable electrode. In order to prevent this sticking, the movable electrode and the detection electrode are short-circuited and anodic-bonded in a state where electrostatic force does not work, and then the short-circuited electrodes are separated using a laser. In addition, it is necessary to perform laser-assisted etching after bonding to a glass substrate to form an island-shaped fixed electrode. These laser processes are extremely complicated and unsuitable for mass production of sensors.

[0006] In the micro gyro, since a silicon wafer is used as a substrate, the parasitic capacitance of the sensor is large, and it is difficult to increase sensitivity and accuracy. Further, in the gyroscope manufacturing method, since the entire structure is formed by using the portion where boron is diffused as an etch stop portion, if the etch stop effect is incomplete, the thickness of the movable electrode and the fixed electrode is reduced by overetching. Therefore, there is a problem that the dimensional accuracy is inferior. Further, since the gap between the movable electrode and the detection electrode depends only on the control by the etching time, there is a problem in the accuracy of forming the gap between the electrodes.

An object of the present invention is to provide a method of manufacturing a low-cost semiconductor inertial sensor which does not require laser processing and is suitable for mass production. Another object of the present invention is to provide a method of manufacturing a semiconductor inertial sensor with low parasitic capacitance, high sensitivity and high accuracy. Still another object of the present invention is to provide a method for manufacturing a semiconductor inertial sensor having excellent dimensional accuracy.

[0008]

The invention according to claim 1 is
As shown in FIG. 1, a first silicon wafer 2 having a first film 41 that can be etched without eroding silicon on both surfaces.
Bonding a second silicon wafer 22 to 1;
A step of polishing one surface of the first silicon wafer 21 to a predetermined thickness to form a first single-crystal silicon layer 51, and a third silicon wafer having on both surfaces a second film 42 that can be etched without eroding silicon. Bonding the first silicon crystal layer 23 to the first single crystal silicon layer 51;
Is ground to a predetermined thickness to form a second monocrystalline silicon layer 5
Forming the second monocrystalline silicon layer 52 and the second film 42 under the second monocrystalline silicon layer 52 by selective etching.
The single crystal silicon layer 51 is exposed, and the spacer layer 24 including the remaining second single crystal silicon layer 52 and the second film 42 is formed.
Forming a first monocrystalline silicon layer 51
Is selectively removed by etching, thereby forming the movable electrode 26 made of single-crystal silicon on the first film 41 and connecting to the spacer layer 24 on both sides of the movable electrode 26 on the first film 41. A step of forming a pair of fixed electrodes 27 and 28 made of single crystal silicon, a step of forming a second silicon wafer 22, a first film 41, a movable electrode 26 and a fixed electrode 2;
Bonding the structure 25 having the spacers 24 to the glass substrate 10 via the spacer layer 24 such that the movable electrode 26 faces the glass substrate 10; and bonding the second silicon wafer 22 to the first film. A step of etching and removing the first film 41 as an etch stop layer; and a step of etching and removing the first film 41 and the movable electrode 26 sandwiched between the pair of fixed electrodes 27 and 28 and floating above the glass substrate 10. Obtaining a semiconductor inertial sensor 30 having the following.

According to a second aspect of the present invention, as shown in FIG. 4, a step of forming a detection electrode 12 on a glass substrate 10 and a first step capable of etching both sides without eroding silicon.
A step of bonding the second silicon wafer 22 to the first silicon wafer 21 having the film 41, and a step of polishing one surface of the first silicon wafer 21 to a predetermined thickness to form a first single-crystal silicon layer 51; Bonding a third silicon wafer 23 having a second film 42 that can be etched without eroding silicon on both surfaces to the first single crystal silicon layer 51, and polishing one surface of the third silicon wafer 23 to a predetermined thickness. Forming a second single-crystal silicon layer 52, and selectively removing the second single-crystal silicon layer 52 and the second film 42 thereunder by exposing the first single-crystal silicon layer 51; Residual second single crystal silicon layer 52
Forming the spacer layer 24 composed of the first film 41 and the second film 42, and selectively removing the exposed first single crystal silicon layer 51 by etching, thereby forming the movable electrode 26 composed of the single crystal silicon on the first film 41. And forming a structure 25 having the second silicon wafer 22, the first film 41, the movable electrode 26, and the spacer layer 24 via the spacer layer 24 such that the movable electrode 26 faces the detection electrode 12. A step of bonding the second silicon wafer 22 to the substrate 10, a step of etching and removing the second silicon wafer 22 using the first film 41 as an etch stop layer, and a step of etching and removing the first film 41 to face the detection electrode 12 on the glass substrate 10. Obtaining a semiconductor inertial sensor 40 having a movable electrode 26 that floats.

According to a third aspect of the present invention, as shown in FIG. 5, a step of forming a detection electrode 12 on a glass substrate 10 and a first step capable of etching both sides without eroding silicon.
A step of bonding the second silicon wafer 22 to the first silicon wafer 21 having the film 41, and a step of polishing one surface of the first silicon wafer 21 to a predetermined thickness to form a first single-crystal silicon layer 51; Bonding a third silicon wafer 23 having a second film 42 that can be etched without eroding silicon on both surfaces to the first single crystal silicon layer 51, and polishing one surface of the third silicon wafer 23 to a predetermined thickness. Forming a second single-crystal silicon layer 52, and selectively removing the second single-crystal silicon layer 52 and the second film 42 thereunder by exposing the first single-crystal silicon layer 51; Residual second single crystal silicon layer 52
Forming the spacer layer 24 composed of the first film 41 and the second film 42, and selectively removing the exposed first single crystal silicon layer 51 by etching, thereby forming the movable electrode 26 composed of the single crystal silicon on the first film 41. And a pair of fixed electrodes 27 made of single-crystal silicon, which are located on both sides of the movable electrode 26 on the first film 41 and are connected to the spacer layer 24,
And forming a structure 25 having the second silicon wafer 22, the first film 41, the movable electrode 26, the fixed electrodes 27 and 28, and the spacer layer 24 so that the movable electrode 26 faces the detection electrode 12. Bonding to the glass substrate 10 via the spacer layer 24 and the second silicon wafer 22
Is etched using the first film 41 as an etch stop layer, and the first film 41 is etched away to detect the pair of fixed electrodes 27, 28 and the fixed electrodes 27, 28 and detect them on the glass substrate 10. Obtaining a semiconductor inertial sensor 50 having a movable electrode 26 floating opposite to the electrode 12.

In the manufacturing method according to the first to third aspects, since laser processing of the wafer is unnecessary and suitable for mass production, a semiconductor inertial sensor can be manufactured at low cost. Since the constituent members of the structure 25 are composed of the second silicon wafer 22 and the single crystal silicon layer 51 obtained by polishing the first silicon wafer 21 bonded to the second silicon wafer 22 to a predetermined thickness,
The thickness of the structure can be freely selected. Therefore, the structure 25
In addition, the handling when bonding to the glass substrate 10 becomes easy, and the thickness of the movable electrode 26 and the like can be set freely. Further, since a glass substrate is used as the substrate, the obtained semiconductor inertial sensor has low parasitic capacitance. Further, the gap between the electrodes is not controlled by the etching time but is determined by the thickness of the spacer layer 24 composed of the second single crystal silicon layer 52 and the second film 42, so that the dimensional accuracy is excellent. For this reason, a highly accurate semiconductor inertial sensor is manufactured.

In this specification, "a film which can be etched without eroding silicon" means that an etchant which does not corrode silicon when etching the film can be selected. . Examples of the film having such properties include an oxide film and a nitride film. In the present invention, the crystal orientation of the second silicon wafer 22 is preferably a (110) orientation in consideration of the etching rate.

[0013]

Embodiments of the present invention will be described in detail with reference to the drawings. As shown in FIGS. 1 and 2, the semiconductor inertial sensor 30 according to the first embodiment of the present invention is an acceleration sensor, and a spacer including a second single-crystal silicon layer 52 and a second film 42 on a glass substrate 10. A movable electrode 26 is provided between fixed electrodes 27 and 28 fixed via a layer 24. The movable electrode 26 and the fixed electrodes 27 and 28 are each made of single-crystal silicon, and opposing portions of the electrode 26 and the electrode 27 and the electrode 26 and the electrode 28 are formed in a comb shape. The movable electrode 26 is supported at both ends by beams 31, and floats with respect to the glass substrate 10. The base 31 a of the beam 31 is fixed on the glass substrate 10 via the spacer layer 24. Although not shown, electric wires are individually provided to the beam base 31a and the fixed electrodes 27 and 28. In the semiconductor inertial sensor 30, when a horizontal acceleration perpendicular to a line connecting the beam base ends 31a and 31a acts on the movable electrode 26 as shown by arrows in the figure, the movable electrode 26 applies the beams 31, 31. Vibrates around the shaft. When the distance between the movable electrode 26 and the fixed electrodes 27 and 28 increases or decreases, the movable electrode 2
The capacitance between the fixed electrode 6 and the fixed electrodes 27 and 28 changes.
The acceleration that acts is obtained from the change in the capacitance.

Next, a method of manufacturing the semiconductor inertial sensor 30 according to the first embodiment of the present invention will be described. As shown in FIG. 1, a film 41 that can be etched without eroding silicon is formed on both surfaces of the first silicon wafer 21. This film 41
As an oxide film formed by thermally oxidizing a silicon wafer, or by using a chemical vapor deposition (CVD) method.
A silicon nitride film formed using H 2 Cl 2 or SiH 4 and NH 3 gas can be used. After forming the first thermal oxide film 41 on both surfaces of the first silicon wafer 21, the second silicon wafer 22 is bonded to the first silicon wafer 21 via the first thermal oxide film 41. The surface of the first silicon wafer 21 on the side where the second silicon wafer 22 is not bonded is placed on the first thermal oxide film 4 formed thereon.
The first single-crystal silicon layer 51 is formed by grinding and polishing to a predetermined thickness using a grindstone and a polishing cloth together with 1. Further, a second thermal oxide film 42 is formed on both surfaces of the third silicon wafer 23. The third silicon wafer 23 is bonded to the first single crystal silicon layer 51 via the second thermal oxide film 42. The surface of the third silicon wafer 23 is ground and polished to a predetermined thickness using a grindstone and a polishing cloth together with the second thermal oxide film 42 formed thereon to form the second single-crystal silicon layer 52. After the surfaces of the second single crystal silicon layer 52 and the second silicon wafer 22 are thermally oxidized, patterning is performed to selectively form the third thermal oxide film 43, and wet etching is performed using an etchant such as KOH. As a result, the portion of the second single crystal silicon layer 52 where the third thermal oxide film 43 is not formed is removed by etching. Thereafter, the second thermal oxide film 42 is removed by etching using an etchant such as hydrofluoric acid, so that the first single-crystal silicon layer 51 is exposed and the remaining second single-crystal silicon layer 52 and the second thermal oxide film 42 are removed. The spacer layer 24 having a two-layer structure is formed. After removing the third thermal oxide film 43, an Al layer 35 is selectively formed on the surface of the first single crystal silicon layer 51 including the spacer layer 24 by sputtering and patterning,
Subsequently, low-temperature anisotropic dry etching using SF 6 gas is performed. As a result, the first single crystal silicon layer 51 is selectively etched using the first thermal oxide film 41 as an etch stop layer. As a result, the movable electrode 26 made of single crystal silicon is formed on the first thermal oxide film 41, This movable electrode 2
A pair of fixed electrodes 27 and 28 made of single crystal silicon are formed on both sides of 6 with a slight gap. After removing the Al layer 35, the structure 25 having the second silicon wafer 22, the first thermal oxide film 41, the movable electrode 26, the pair of fixed electrodes 27 and 28, and the spacer layer 24 is attached to the glass substrate 10. Anodically bond to the glass substrate 10 via the spacer layer 24 so as to face each other. Subsequently, the second silicon wafer 22 is etched and removed by an etchant such as KOH using the first thermal oxide film 41 as an etch stop layer.
Next, the first thermal oxide film 41 is etched away by wet etching using an etchant such as hydrofluoric acid or dry etching using an etchant such as CF 4 . As a result, a semiconductor inertial sensor 30 in which the movable electrode 26 made of single-crystal silicon is sandwiched between the pair of fixed electrodes 27 and 28 made of single-crystal silicon and formed above the glass substrate 10 so as to float is obtained.

FIGS. 3 and 4 show a semiconductor inertial sensor 40 according to a second embodiment. The semiconductor inertial sensor 40 is an acceleration sensor, and has a movable electrode 26 between a frame 29 fixed on a glass substrate 10 via a spacer layer 24 composed of a second single crystal silicon layer 52 and a second film 42. Having. The movable electrode 26 and the frame body 29 are each made of single crystal silicon, and the movable electrode 26 is accommodated in the window frame-shaped frame body 29 at intervals. The movable electrode 26 is supported at both ends by beams 31, and floats with respect to the glass substrate 10. The base end 31 a of the beam 31 is located in the recess 29 a of the frame 29 and the spacer layer 24 on the glass substrate 10.
Is fixed through. The detection electrode 1 is provided on the glass substrate 10.
2 are formed. Although not shown, electric wires are individually provided to the beam base 31a and the detection electrode 12. In the semiconductor inertial sensor 40, when a vertical acceleration perpendicular to a line connecting the beam base ends 31a and 31a acts on the movable electrode 26 as shown by arrows in FIG.
6 oscillates with the beams 31, 31 as pivots. When the distance between the movable electrode 26 and the detection electrode 12 increases or decreases, the capacitance between the movable electrode 26 and the detection electrode 12 changes. The acceleration that acts is obtained from the change in the capacitance.

Next, a method of manufacturing the semiconductor inertial sensor 40 according to the second embodiment of the present invention will be described. As shown in FIG. 4, first, a detection electrode 12 made of a thin film of a metal selected from Au, Pt, Cu, or the like is formed on a glass substrate 10 by sputtering, vacuum deposition, or the like. On the other hand, the first silicon wafer 21 is formed in the same manner as in the manufacturing method of the first embodiment.
Is thermally oxidized to form first thermal oxide films 41 on both surfaces thereof. Next, the second silicon wafer 22 is bonded to the first silicon wafer 21 via the first thermal oxide film 41. The surface of the first silicon wafer 21 on the side where the second silicon wafer 22 is not bonded is ground and polished to a predetermined thickness using a grindstone and a polishing cloth together with the first thermal oxide film 41 formed thereon. First single crystal silicon layer 5
Form one. Further, a second thermal oxide film 42 is formed on both surfaces of the third silicon wafer 23. The third silicon wafer 23 is formed on the first single-crystal silicon layer 51 by the second thermal oxide film 42.
Paste through. The surface of the third silicon wafer 23 is ground and polished to a predetermined thickness using a grindstone and a polishing cloth together with the second thermal oxide film 42 formed thereon to form the second
A single crystal silicon layer 52 is formed. After the surfaces of the second single crystal silicon layer 52 and the second silicon wafer 22 are thermally oxidized and patterned to selectively form the third thermal oxide film 43, wet etching is performed with an etchant such as KOH. As a result, the portion of the second single crystal silicon layer 52 where the third thermal oxide film 43 is not formed is removed by etching. After that, the second thermal oxide film 42 is removed by etching using an etchant such as hydrofluoric acid.
The single-crystal silicon layer 51 is exposed, and the spacer layer 24 having a two-layer structure including the remaining second single-crystal silicon layer 52 and the second thermal oxide film 42 is formed. After removing the third thermal oxide film 43, the first single crystal silicon layer 5 including the spacer layer 24 is formed.
Al on the surface of 1 by sputtering and patterning
The layer 35 is selectively formed, followed by low-temperature anisotropic dry etching using SF 6 gas. As a result, the first single crystal silicon layer 51 is selectively etched using the first thermal oxide film 41 as an etch stop layer. As a result, the movable electrode 26 made of single crystal silicon is formed on the first thermal oxide film 41, Frames 29 made of single crystal silicon are formed on both sides of the movable electrode 26 with a slight gap. Al
After removing the layer 35, the second silicon wafer 22 and the first silicon wafer 22 are removed.
Thermal oxide film 41, movable electrode 26, frame 29, and spacer layer 2
The movable electrode 26 is formed on the glass substrate 10
Is anodically bonded to the glass substrate 10 via the spacer layer 24 so as to face the detection electrode 12 of FIG. Subsequently, the second silicon wafer 22 is moved to the first silicon wafer 22 by an etchant such as KOH.
The thermal oxide film 41 is removed by etching as an etch stop layer. Next, the first thermal oxide film 41 is etched away by wet etching using an etchant such as hydrofluoric acid or dry etching using an etchant such as CF 4 . Thereby, the movable electrode 2 made of single crystal silicon
6 is a semiconductor inertial sensor 4 which is surrounded by a frame 29 made of single crystal silicon and floats opposite to the detection electrode 12.
0 is obtained.

FIGS. 5 and 6 show a semiconductor inertial sensor 50 according to a third embodiment. The semiconductor inertial sensor 50 is an angular velocity sensor, and has a tuning fork between fixed electrodes 27 and 28 fixed on a glass substrate 10 via a spacer layer 24 including a second single-crystal silicon layer 52 and a second film 42. It has a pair of movable electrodes 26, 26 having a structure. The movable electrode 26 and the fixed electrodes 27 and 28 are each made of single-crystal silicon, and opposing portions of the electrode 26 and the electrode 27 and the electrode 26 and the electrode 28 are formed in a comb shape. Movable electrode 26, 2
Numeral 6 is supported at both ends by U-shaped beams 31, 31 and floats on the glass substrate 10. The base 31 a of the beam 31 is fixed on the glass substrate 10 via the spacer layer 24. The detection electrode 12 is formed on the glass substrate 10. Although not shown, the beam base end 31
a, the fixed electrodes 27 and 28, and the detection electrode 12 are individually provided with electric wiring, and an alternating voltage is applied to the fixed electrodes 27 and 28 to excite the movable electrode by electrostatic force. In the semiconductor inertial sensor 50, the movable electrodes 26, 2
When an angular velocity acts on the line 6 centering on the line connecting the beam base ends 31a and 31a, Coriolis force is generated in the movable electrodes 26, 26, causing torsional vibration around the center line and resonating. The angular velocity acting due to the change in the capacitance between the movable electrode 26 and the detection electrode 12 at the time of the resonance is detected.

Next, a method of manufacturing the semiconductor inertial sensor 50 according to the third embodiment of the present invention will be described. As shown in FIG. 5, first, as in the second embodiment, a detection electrode 12 made of a thin film of a metal selected from Au, Pt, Cu, or the like is formed on a glass substrate 10 by sputtering, vacuum deposition, or the like. On the other hand, in the same manner as in the manufacturing method of the first embodiment,
The first thermal oxide film 41 is formed on both surfaces of the silicon wafer 21 by thermal oxidation. Next, the second silicon wafer 22 is bonded to the first silicon wafer 21 via the first thermal oxide film 41. Second silicon wafer 22
The first silicon wafer 21 on the side where is not bonded
Is ground and polished to a predetermined thickness using a grindstone and a polishing cloth together with the first thermal oxide film 41 formed thereon to form a first single-crystal silicon layer 51. Further, a second thermal oxide film 42 is formed on both surfaces of the third silicon wafer 23. This third silicon wafer 23 is placed on the first single crystal silicon layer 5.
1 with the second thermal oxide film 42 interposed therebetween. The surface of the third silicon wafer 23 is formed on the second silicon wafer 23
The second single-crystal silicon layer 52 is formed by grinding and polishing to a predetermined thickness using a grindstone and a polishing cloth together with the thermal oxide film 42. After the surfaces of the second single crystal silicon layer 52 and the second silicon wafer 22 are thermally oxidized and patterned to selectively form the third thermal oxide film 43, wet etching is performed with an etchant such as KOH. As a result, the portion of the second single crystal silicon layer 52 where the third thermal oxide film 43 is not formed is removed by etching. Thereafter, the second thermal oxide film 42 is removed by etching using an etchant such as hydrofluoric acid, so that the first single crystal silicon layer 51 is exposed and the remaining second single crystal silicon layer 52 and the second thermal oxide film 42 are removed. The spacer layer 24 having a two-layer structure is formed. After removing the third thermal oxide film 43, an Al layer 35 is selectively formed on the surface of the first single crystal silicon layer 51 including the spacer layer 24 by sputtering and patterning,
Subsequently, low-temperature anisotropic dry etching using SF 6 gas is performed. As a result, the first single crystal silicon layer 51 is selectively etched using the first thermal oxide film 41 as an etch stop layer. As a result, the movable electrode 26 made of single crystal silicon is formed on the first thermal oxide film 41, This movable electrode 2
A pair of fixed electrodes 27 and 28 made of single crystal silicon are formed on both sides of 6 with a slight gap. After removing the Al layer 35, the structure 25 having the second silicon wafer 22, the first thermal oxide film 41, the movable electrode 26, the pair of fixed electrodes 27 and 28, and the spacer layer 24 is replaced with the movable electrode 26 of the glass substrate 10. The spacer layer 2 is opposed to the detection electrode 12.
4 and anodically bonded to the glass substrate 10. Then, K
2nd silicon wafer 2 by etchant such as OH
2 is removed by etching using the first thermal oxide film 41 as an etch stop layer. Next, the first thermal oxide film 41 is etched away by wet etching using an etchant such as hydrofluoric acid or dry etching using an etchant such as CF 4 . As a result, the movable electrode 26 made of single-crystal silicon becomes a pair of fixed electrodes 2 made of single-crystal silicon.
The semiconductor inertial sensor 50 is formed so as to float between the detection electrodes 12 and 7 between the detection electrodes 12 and 7.

[0019]

As described above, unlike the conventional method of manufacturing a semiconductor inertial sensor by laser processing of a wafer, according to the present invention, laser processing of a wafer is unnecessary and a low-cost semiconductor inertial sensor suitable for mass production. Can be manufactured. By using a glass substrate instead of a silicon substrate for a sensor that performs detection using capacitance, the parasitic capacitance of the element is reduced, and a highly sensitive and accurate semiconductor inertial sensor can be obtained. Since the single-crystal silicon layer forming the movable electrode, the fixed electrode, the frame, or the like is bonded to the silicon substrate while being supported by the second silicon wafer, a sticking phenomenon unlike the related art does not occur, and the detection electrode is not generated. The movable electrode can be provided at a predetermined gap with respect to the silicon substrate. Further, since the movable electrode and the like are made of single-crystal silicon, they have excellent mechanical properties as compared with polycrystalline silicon and metal. In the structure in which the detection electrode is formed on the glass substrate, the gap between the glass substrate on which the detection electrode is formed and the movable electrode is defined by the thickness of the spacer layer, so that the gap can be formed with high precision.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a semiconductor inertial sensor according to a first embodiment of the present invention, corresponding to a main part of line AA in FIG. 2, and a manufacturing process thereof.

FIG. 2 is an external perspective view of the semiconductor inertial sensor according to the first embodiment of the present invention.

FIG. 3 is an external perspective view of a semiconductor inertial sensor according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a semiconductor inertial sensor according to a second embodiment of the present invention corresponding to a main part of line BB in FIG. 3 and a manufacturing process thereof.

FIG. 5 is a sectional view showing a semiconductor inertial sensor according to a third embodiment of the present invention, corresponding to a main part of line CC in FIG. 6, and a manufacturing process thereof;

FIG. 6 is an external perspective view of a semiconductor inertial sensor according to a third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 glass substrate 12 detection electrode 21 first silicon wafer 22 second silicon wafer 23 third silicon wafer 24 spacer layer 25 structure 26 movable electrode 27, 28 pair of fixed electrodes 30, 40, 50 semiconductor inertial sensor 41 first film 42 Second film 51 First monocrystalline silicon layer 52 Second monocrystalline silicon layer

Claims (3)

[Claims]
1. a step of bonding a second silicon wafer (22) to a first silicon wafer (21) having a first film (41) that can be etched without eroding silicon on both sides; Polishing one side of (21) to a predetermined thickness to form a first single-crystal silicon layer (51); and a second film (4) capable of etching both sides without eroding silicon.
Bonding a third silicon wafer (23) having 2) to the first single crystal silicon layer (51); polishing one surface of the third silicon wafer (23) to a predetermined thickness to form a second silicon wafer (23). Forming a crystalline silicon layer (52); and selectively etching and removing the second single crystal silicon layer (52) and the second film (42) thereunder.
(51) exposing, forming a spacer layer (24) composed of the remaining second single-crystal silicon layer (52) and the second film (42); and forming the exposed first single-crystal silicon layer (51). ) Is selectively etched away, thereby forming a movable electrode (26) made of single-crystal silicon on the first film (41), and
(41) forming a pair of fixed electrodes (27, 28) made of single-crystal silicon on both sides of the movable electrode (26) and connected to the spacer layer (24) on the (41); A wafer (22), the first film (41), the movable electrode (26), the fixed electrodes (27, 28), and the spacer layer
Bonding the structure (25) having the (24) to the glass substrate (10) via the spacer layer (24) such that the movable electrode (26) faces the glass substrate (10); Etching the second silicon wafer (22) using the first film (41) as an etch stop layer; and etching and removing the first film (41) to form the pair of fixed electrodes (27, 28). The movable electrode (2) sandwiched between the fixed electrodes (27, 28) and floating above the glass substrate (10)
6) obtaining a semiconductor inertial sensor (30) having the following steps:
A step of forming a detection electrode on a glass substrate; and a step of etching a first film on both sides without eroding silicon.
Bonding a second silicon wafer (22) to a first silicon wafer (21) having (1); polishing one surface of the first silicon wafer (21) to a predetermined thickness to form a first monocrystalline silicon layer; (51) forming a second film (4) that can be etched without eroding silicon on both sides.
Bonding a third silicon wafer (23) having 2) to the first single crystal silicon layer (51); polishing one surface of the third silicon wafer (23) to a predetermined thickness to form a second silicon wafer (23). Forming a crystalline silicon layer (52); and selectively etching and removing the second single crystal silicon layer (52) and the second film (42) thereunder.
(51) exposing, forming a spacer layer (24) composed of the remaining second single-crystal silicon layer (52) and the second film (42); and forming the exposed first single-crystal silicon layer (51). ) Is selectively removed by etching to thereby form a movable electrode (26) made of single-crystal silicon on the first film (41); and the second silicon wafer (22) and the first film ( 41), the movable electrode (26), and the structure (2) having the spacer layer (24).
5) The glass substrate (10) via the spacer layer (24) such that the movable electrode (26) faces the detection electrode (12)).
Bonding the second silicon wafer (22) to the glass substrate by etching and removing the first film (41) using the first film (41) as an etch stop layer; 10) obtaining a semiconductor inertial sensor (40) having the movable electrode (26) floating on the detection electrode (12).
3. A step of forming a detection electrode (12) on a glass substrate (10), and a first film (4) which can be etched on both sides without eroding silicon.
Bonding a second silicon wafer (22) to a first silicon wafer (21) having (1); polishing one surface of the first silicon wafer (21) to a predetermined thickness to form a first monocrystalline silicon layer; (51) forming a second film (4) that can be etched without eroding silicon on both sides.
Bonding a third silicon wafer (23) having 2) to the first single crystal silicon layer (51); polishing one surface of the third silicon wafer (23) to a predetermined thickness to form a second silicon wafer (23). Forming a crystalline silicon layer (52); and selectively etching and removing the second single crystal silicon layer (52) and the second film (42) thereunder.
(51) exposing, forming a spacer layer (24) composed of the remaining second single-crystal silicon layer (52) and the second film (42); and forming the exposed first single-crystal silicon layer (51). ) Is selectively etched away, thereby forming a movable electrode (26) made of single-crystal silicon on the first film (41), and
(41) forming a pair of fixed electrodes (27, 28) made of single-crystal silicon on both sides of the movable electrode (26) and connected to the spacer layer (24) on the (41); A wafer (22), the first film (41), the movable electrode (26), the fixed electrodes (27, 28), and the spacer layer
Bonding the structure (25) having the (24) to the glass substrate (10) via the spacer layer (24) such that the movable electrode (26) faces the detection electrode (12). Etching the second silicon wafer (22) using the first film (41) as an etch stop layer; and etching the first film (41) to remove the pair of fixed electrodes (27, 28). ) And the fixed electrode (27, 28) and the semiconductor inertial sensor (5) having the movable electrode (26) floating on the glass substrate (10) in opposition to the detection electrode (12).
0) obtaining a semiconductor inertial sensor.
JP9072956A 1997-03-26 1997-03-26 Manufacture of semiconductor inertia sensor Withdrawn JPH10270714A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP9072956A JPH10270714A (en) 1997-03-26 1997-03-26 Manufacture of semiconductor inertia sensor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP9072956A JPH10270714A (en) 1997-03-26 1997-03-26 Manufacture of semiconductor inertia sensor

Publications (1)

Publication Number Publication Date
JPH10270714A true JPH10270714A (en) 1998-10-09

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