JPH04315477A - Three-dimensional acceleration sensor - Google Patents

Abstract

PURPOSE:To simplify a structure to reduce a cost by preventing the breakage of a cantilever during a wafer process through constituting the cantilever on one chip and by providing an air-damping system through forming a narrow gap easily and with good controllability. CONSTITUTION:In a three-dimensional acceleration sensor comprising three detecting elements formed in a semiconductor substrate 10 for the purpose of detecting a three-dimensional acceleration, respective detecting elements are constituted by cantilevers 100, 200 and 300 functioning as piezoresistances.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional acceleration sensor.

0002

2. Description of the Related Art Conventional acceleration sensors include those shown in FIGS. 18 and 19, for example ("A Bat
ch Fabricated Silicon Acc
elerometer”IEEE Trans.E
lectron Dev. , vol. ED-26,1
979). In these figures, 91 is a silicon semiconductor substrate, and on the semiconductor substrate 91, a thin cantilever 92 with one end supported by a fixing part 91a is formed by etching, and the tip of the cantilever 92 has a A mass portion 93 is formed using the entire thickness of the semiconductor substrate 91 as it is. cantilever beam 9
A piezoresistor 94 is formed near the support portion 2 by a diffusion layer of a conductivity type different from that of the semiconductor substrate 91. A piezoresistor 95 is also formed on the surface of the fixed part 91a by a similar diffusion layer.
is formed. The two piezoresistors 94 and 95 constitute a half bridge in a bridge circuit for detecting acceleration. Then, on both the upper and lower surfaces of the semiconductor substrate 91 on which the cantilever beam 92, the mass part 93, etc. are formed, two glass plates 96 are formed, in which recesses of a required depth are etched to serve as an upper stopper and a lower stopper. 97 is glued. Further, damper oil is sealed in the space around the cantilever beam 92 and the mass portion 93 in order to increase impact resistance and the like.

0003

[Problems to be Solved by the Invention] In conventional acceleration sensors, a mass part using the entire thickness of the semiconductor substrate was formed at the tip of a thin cantilever, so the cantilever was damaged during the wafer process. There is a problem in that the yield tends to decrease due to the occurrence of. In addition, because two glass plates, which are separate members from the semiconductor substrate, were glued to the top and bottom surfaces of the semiconductor substrate to form the upper and lower stoppers, it was difficult to control a narrow gap and air damping was not possible. Required to be filled with oil. For this reason, there have been problems in that the mounting cost is high and the structure is complicated, resulting in high cost.

[0004] Accordingly, the present invention can prevent damage to the cantilever beam during wafer processing by configuring it on one chip, and can form a narrow gap easily and with good controllability. It is an object of the present invention to provide a three-dimensional acceleration sensor that can use a damping method, has a simple structure, and can reduce costs.

[0005]

[Means for Solving the Problems] In order to solve the above problems, the present invention first provides a three-dimensional acceleration sensor in which three detection parts for detecting three-dimensional acceleration are formed on a semiconductor substrate. The gist of the present invention is that each of the detection parts is constituted by a cantilever made of a semiconductor layer functioning as a piezoresistor and an oxide film laminated thereon.

Second, there is a three-dimensional acceleration sensor in which three detection parts for detecting three-dimensional acceleration are formed on a semiconductor substrate, each of the detection parts having a cantilever made of a semiconductor layer;
The main feature is that the capacitor is configured with an opposing wall forming a capacitor between the cantilever beam and the cantilever beam.

[0007]

[Operation] In the first invention, the vibration change or displacement of each cantilever beam corresponding to the acceleration to be tested is converted into a change in electric signal by the piezoresistor constituted by each cantilever beam itself, and a three-dimensional signal is generated. An acceleration component is detected.

In the second invention, the vibration change or displacement of each cantilever beam corresponding to the acceleration to be tested is converted into a change in capacitance by a capacitor constituted by the cantilever beam and the opposing wall. A dimensional acceleration component is detected.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 are diagrams showing a first embodiment of the present invention.

First, the configuration of a three-dimensional acceleration sensor will be explained using FIG. 1. FIG. 1(a) is a plan view, and FIG. 1(b) is a sectional view taken along line AA and line BB in FIG. 1(a). In these figures, 1 is an n-type substrate, 2 is a p+ buried layer, and as described later, first and second n-type epitaxial layers 3 and 4 are formed on the n-type substrate 1 to form an epitaxial semiconductor. A substrate 10 is configured. A cavity 5 is recessed in the surface of the epitaxial semiconductor substrate 10, and a cantilever 100 extends from the inner wall of the cavity 5 into the cavity 5 to detect acceleration in the direction perpendicular to the substrate surface (Z direction). A cantilever beam 200 for detecting acceleration in the X direction and a cantilever beam 300 for detecting acceleration in the Y direction are each formed. Each cantilever 100, 200, 300 has a p-type single crystal semiconductor layer 6,
The laminated structure of 8, 11 and oxide films 7, 9, 12 forms a resonator that can be excited by a bimetal effect. Further, each of the cantilevers 100, 200, and 300 is formed in a U shape, and the entire U-shaped p-type single crystal semiconductor layers 6, 8, and 11 are used as piezoresistors. 13 and 14 are p+ connections of piezoresistors in the cantilever beam 100, 15 and 1
6 is the p+ connection of the piezoresistor in the cantilever beam 200, 1
7 and 18 are p+ connections of piezoresistors in the cantilever beam 300.

[0012] The above cavity 5 and each cantilever beam 100, 20
0 and 300 are formed by etching using a p+ region etc. as an etch stop, 25 is a p+ diffusion region for this purpose, and 19 is a recess for preventing etching of the n type region. 21 is a nitride layer serving as a spacer, and 22 is a semiconductor chip serving as a capping layer. The cavity 5 is sealed by the semiconductor chip 22.

The three-dimensional acceleration sensor of this embodiment is constructed as described above, and vibration changes of the cantilever beams 100, 200, and 300 in the vertical direction, X direction, and Y direction corresponding to the acceleration to be detected are Each piezoresistor converts it into an electric signal, that is, a change in frequency, and a three-dimensional acceleration component is detected, and the direction and magnitude of the acceleration of the system is detected from the sum of these three-dimensional acceleration components. At this time, since a narrow gap is formed with good controllability between the side wall and bottom wall of the cavity 5 of each cantilever beam 100, 200, 300,
These gaps provide reliable air damping.

Next, an example of the construction process of the three-dimensional acceleration sensor of this embodiment will be explained using FIG.

(a) A p+ buried layer 2 is formed on the main surface of the n-type substrate 1.
is formed, and a first n-type epitaxial layer 3 is formed thereon. p in the required portions of the first n-type epitaxial layer
A + diffusion region 23 is formed, and then a p+ buried layer 24 is formed. A second n-type epitaxial layer 4 is formed on the p+ buried layer 24 and the like. P in the second n-type epitaxial layer 4
The + diffusion region 25 is formed deeply, and the p+ diffusion layer 26 is further formed.
form. This p+ diffusion layer 26 forms a cantilever beam 100 for measuring acceleration in the vertical direction (FIG. 2(a)).
.

(b) After forming the oxide film 7 on the substrate surface,
A nitride layer 21, which serves as a spacer between each cantilever and the capping layer, is deposited and patterned. p+ buried layer 24
A groove is formed by etching until the depth of the groove is etched, and the inner wall of the groove is oxidized to form oxide films 9 and 12. The trench is filled with polysilicon 27 (FIGS. 2(b) and 2(c)).

(c) RIE (reactive ion etching)
to form the planar shape of each cantilever beam 100, 200, 300 (Fig. 2(
d), (e)).

(d) The n-type regions of the first and second n-type epitaxial layers 3 and 4 are removed by KOH (potassium hydroxide) etching. In the KOH etching, each p+ diffusion region 2, 23, 24, 25, 26 serves as an etch stop to form a cavity 5 and each cantilever beam 100, 200, 300. Finally, a semiconductor chip 22 serving as a capping layer is attached to seal the cavity 5 (FIG. 2(f)).

FIGS. 3 and 4 show a second embodiment of the invention.

FIG. 3(a) is a plan view, and FIG. 3(b) is a plan view of the same figure (
It is a sectional view taken along the AA line and the BB line in a).

In addition, in FIGS. 3, 4, and the figures showing each embodiment described later, the same or equivalent members and parts as in FIGS. 1 and 2 are designated by the same reference numerals,
Omit duplicate explanations.

In this embodiment, a detection section detects acceleration in the direction perpendicular to the substrate surface using a capacitor with the cantilever beam 101 as a movable electrode and the p+ buried layer 2 forming the bottom wall of the cavity 5 as a counter electrode. is configured. The capacitance of this capacitor is measured between cantilever 101 and p+ region 28. The cantilever beam 201 is used as a movable electrode, and the side wall of the cavity 5 is formed by p.
A detection unit that detects acceleration in the X direction is configured by a capacitor with the + diffusion region 29 as a counter electrode. The capacitance of this capacitor is the p+ diffusion region 29 and p
+ area 31. In addition, the cantilever beam 301 is used as a movable electrode, and the p+ diffusion region 32 forming the side wall of the cavity 5
A detection unit that detects acceleration in the Y direction is configured by a capacitor having a counter electrode as a counter electrode. The capacitance of this capacitor is measured between p+ diffusion region 32 and p+ region 33, which are opposing electrodes. 34 is a nitride layer serving as a capping layer.

The three-dimensional acceleration sensor of this embodiment is constructed as described above, and each cantilever beam 101, 201, The vibration change 301 is converted into a change in capacitance by each capacitor, and a three-dimensional acceleration component is detected. The direction and magnitude of acceleration of the system are detected from the sum of these three-dimensional acceleration components.

Next, an example of the manufacturing process of the three-dimensional acceleration sensor of this embodiment will be explained using FIG.

(a) A p+ buried layer 2 is formed on the main surface of an n-type substrate 1, and a first n-type epitaxial layer 3 is formed thereon. A p+ diffusion region 23 and a p+ diffusion layer 35 are formed at required portions of the first epitaxial layer 3. p+ diffusion layer 3
5 is a cantilever beam 101 of the vertical direction detection part (Fig. 4(a)
).

(b) A second n-type epitaxial layer 4 is formed, and p+ diffusion regions 25 and 36 are formed in the second n-type epitaxial layer 4. The p+ diffusion regions 23 and 25 form a counter electrode 2 in the X-direction detection section and the Y-direction detection section.
9 and 32 are formed (FIG. 4(b)). (c) R.I.
Etching is performed until the p+ buried layer 2 is etched to form the planar shape of each cantilever beam 101, 201, 301 and the side walls that will become the opposing electrodes in the X-direction detection section and the Y-direction detection section (FIG. 4(c)). ).

(d) The void created by the etching process is filled with PSG37, and the nitride layer 2 is used as a spacer.
1 is deposited and patterned. The opening of the nitride layer 21 is filled with PSG 38, and a nitride layer 34 serving as a capping layer is deposited (FIG. 4(d)).

(e) PSGs 37 and 38 are removed by etching through etching holes (not shown), and then KOH etching is performed to remove the first and second n-type epitaxial layers 3,
Each cantilever beam 101, 201, 30 is removed by removing the n-type region of 4.
Complete 1.

FIGS. 5 to 7 show a third embodiment of the present invention.

FIGS. 6(a), 6(b), and 6(c) are cross-sectional views taken along line AA, line BB, and line CC in FIG. 5.

This embodiment is similar to the first embodiment in that each cantilever is formed in a U-shape and the U-shaped semiconductor layer itself functions as a piezoresistor, but , the acceleration components in the X direction, and the Y direction are each detected by two cantilevers. That is, the two cantilevers 102 and 103 detect acceleration in the direction perpendicular to the substrate surface, the two cantilevers 202 and 203 detect acceleration in the X direction, and the two cantilevers 302 and 303 detect acceleration in the Y direction. It is now detected.

Of the two vertical cantilevers 102 and 103, one cantilever 102 has an oxide film 39a on the upper side and a polysilicon layer 41a on the lower side, and the other cantilever 102 has an oxide film 39a on the upper side and a polysilicon layer 41a on the lower side.
03 has a polysilicon layer 41b on the upper side and an oxide film 39 on the lower side.
It has become b. Two cantilevers 202, 203 in the X direction
Both have an oxide film 42 on the opposing inner side and a p-type single crystal semiconductor layer 43 on the opposing outer side. Similarly, the two cantilevers 302 and 303 in the Y direction both have an oxide film 44 on their opposing inner sides.
The opposing outer side is a p-type single crystal semiconductor layer 45. 4
6 and 47 are p+ polysilicon connections of the piezoresistor in the cantilever beam 102, 48 and 49 are p+ polysilicon connections of the piezoresistance in the cantilever beam 103, and 51 and 52 are p+ connections of the piezoresistance in the cantilever beam 202. Department, 53, 54
is the p+ connection of the piezoresistor in the cantilever beam 203, 55
, 56 are the p+ connections of the piezoresistors on the cantilever beam 302, and 57 and 58 are the p+ connections of the piezoresistors on the cantilever beam 303.
This is the connection part.

As described above, the three-dimensional acceleration sensor of this embodiment has a layered structure of one pair of cantilever beams 102 and 103, 202 and 203, and 302 and 303 in the vertical direction, the X direction, and the Y direction. The temperature characteristics of the pair of cantilever beams can be compensated by averaging the frequency outputs of each pair of piezoresistors by reversing the acceleration direction to be tested.

Next, an example of the manufacturing process of the three-dimensional acceleration sensor of this embodiment will be explained using FIG.

(a) A p+ buried layer 2 is formed on the main surface of an n-type substrate 1, and a first n-type epitaxial layer 3 is formed thereon. P+ diffusion region 2 in first n-type epitaxial layer 3
3 is formed, and then a p+ buried layer 24 is formed. Furthermore, a second n-type epitaxial layer 4 is formed, a p+ region 25 is formed deeply in this second n-type epitaxial layer 4, and a p+ diffusion layer 26 is formed shallowly (FIG. 7(a), 5
).

(b) A groove is formed by etching up to the p+ buried layer 24, and the inner wall of the groove is oxidized to form an oxide film 44. Fill the trench with polysilicon 27 (FIG. 7(b))
.

(c) An oxide film 39b is formed on the surface of the substrate and patterned into a desired shape. A polysilicon layer 41 is deposited thereon and doped with boron to make it p+ type (FIG. 7).
(c)).

(d) Oxide film 3 on polysilicon layer 41
9a is formed and patterned into the desired shape (Fig. 7(d)
)).

(e) After etching in a groove shape up to the p+ buried layer 2 by RIE, the n-type regions of the first and second n-type epitaxial layers 3 and 4 are removed by KOH etching, and the cavity 5 is removed. and each cantilever beam 102, 103, 202
, 203, 302, 303 are completed. Finally, the semiconductor chip 22 that will become the capping layer is attached (Fig. 7(e)
)).

FIGS. 8 to 12 show a fourth embodiment of the present invention.

First, the configuration of the three-dimensional acceleration sensor of this embodiment will be explained using FIGS. 8 and 9. Figure 9(a)
, (b) are cross-sectional views taken along line AA and line BB in FIG. 8, respectively.

In this embodiment, a mass portion is formed at the tip of each cantilever. The cantilever beam 104 that detects acceleration in the direction perpendicular to the substrate surface is formed of an n-type single crystal semiconductor, and has a mass portion 104a formed at its tip. A piezoresistor 61 is formed by a p-type diffusion layer near the thin support portion of the cantilever beam 104. 62 is p of the piezoresistor 61
+ Connection part. Cantilever beam 20 that detects acceleration in the X direction
4 consists of a pair of p-type single crystal semiconductor layers 63 and 64,
A thin oxide layer 65 is formed between both semiconductors 63,
64 is separated, and a mass portion 204a is formed at the tip. The p-type single crystal semiconductor layer 63 is formed into a U-shape and is used as a piezoresistor, as in the first embodiment. 69 is the p+ connection of the piezoresistor. Further, the other p-type single crystal semiconductor layer 64 functions as a mechanical support. Similarly, the cantilever beam 304 for detecting acceleration in the Y direction is formed of a pair of p-type single crystal semiconductor layers 66 and 67 and a thin oxide layer 68 between them, and has a mass portion 304a at its tip. It is formed. A p-type single-crystal semiconductor layer 66 is formed in a U-shape and functions as a piezoresistor, and another p-type single-crystal semiconductor layer 67 functions as a mechanical support. 71 is the p+ connection of the piezoresistor.

The three-dimensional acceleration sensor of this embodiment is constructed as described above, with cantilever beams 104, 204, 304 in the vertical direction, X direction, and Y direction corresponding to the acceleration to be detected.
displacement is converted into a change in electrical signal by each piezoresistor, three-dimensional acceleration components are detected, and these three
The acceleration direction and magnitude of the system are detected from the dimensional acceleration component.

Next, an example of the manufacturing process of the three-dimensional acceleration sensor of this embodiment will be explained using FIGS. 10 to 12.

(a) SIMOX (Sep
arated by Implanted Oxyge
A buried oxide layer 72 is formed by the method n). Further, in a portion corresponding to the lower region of the support portion of the cantilever beam 104
An oxide buried layer 73 is formed shallowly by the MOX method. Next, after forming the n-type epitaxial layer 3, a p-type diffusion region 74 is formed (FIG. 10(a)).

(b) An oxide buried layer 75 is formed in the n-type epitaxial layer 3 and the p-type diffusion region 74 by the SIMOX method.
form. The oxide buried layer 75 in the n-type epitaxial layer 3 is for thinning the support part of the cantilever beam 104, and the oxide buried layer 75 in the p-type diffusion region 74 is for thinning the support part of the cantilever beam 104. This is to separate the crystalline semiconductor layers 63 and 66 into upper and lower parts to form a U-shaped piezoresistor (FIG. 10(b),
(c)).

(c) A p-type diffusion layer that will become the piezoresistor 61 is formed in a portion corresponding to the support portion of the cantilever beam 104. Further, a p+ diffusion layer is formed to form a p+ connection portion 62. A first trench reaching the oxide buried layer 72 is formed by etching, and the first trench is filled with oxide to form the oxide layer 68.
(65) is formed (FIG. 10(d)).

(d) Oxide buried layer 72 is removed by etching.
A second trench is formed reaching the oxide layer 76 in the second trench.
Fill it. As a result, each cantilever beam 104, 204, 3
04 and the side wall portion of the cavity 5 are formed (FIGS. 11(a) and 11(b)).

(e) After forming a thin oxide film 77 by a light oxidation process, a nitride layer 21 is deposited and patterned to define the region of the cavity 5. Further, a light oxidation process is performed to form a thin oxide film 78, and a thin nitride film 79 is deposited thereon. After that, the oxide film 78 and the nitride layer 79 are patterned, and the oxide layers 65 and 6 of the cantilever beams 204 and 304 are patterned.
A protective stripe area is formed on top of 8. This stripe region prevents the oxide layers 65 and 68 from being etched when forming the cavity 5 by etching (FIG. 12(a)).

(f) Deposit PSG 81 to form nitride layer 21
Fill the openings and flatten the surface. Next, a nitride layer 34 for capping is deposited (FIG. 12(b)).

(g) The oxide buried layers 72, 73, 75 and the oxide 76 are etched by HF etching to form the cavity 5 and each of the cantilevers 104, 204, 304. At this time, the oxide layer 6 on the cantilever beams 204, 304
Although parts of 5 and 68 are removed by etching, the etching can be suppressed to a minimum due to the protective stripe area (FIG. 12(c)).

FIG. 13 shows a modification of the fourth embodiment. In this modification, p is also applied to the lower surface near the support part of the cantilever beam
A piezoresistor 81 is formed from a shaped diffusion layer. When the cantilever beam 104 is deflected in accordance with the acceleration to be tested, one of the piezoresistors 61 and 81 is stretched and the other is compressed. Therefore, by forming a half bridge with both piezoresistors 61 and 81, detection sensitivity can be increased.

The process for forming the piezoresistor 81 is as follows:
In the manufacturing process of the fourth embodiment, the ion implantation process for forming the second oxide buried layer 73 is omitted, and instead, the piezoresistor is formed by a p-type diffusion process before forming the n-type epitaxial layer 3. 81, and the p+ diffusion region 82 is formed in contact with the piezoresistor 81. Also, X
Regarding the cantilevers 204 and 304 in the direction and the Y direction, the p-type single crystal semiconductor layers on both sides may be made of piezoresistors in the same manner as described above.

FIGS. 14 to 17 show the fifth embodiment of the present invention.
An example is shown.

FIGS. 15(a) and 15(b) are respectively similar to FIG.
FIG. 4 is a cross-sectional view taken along line A-A and line B-B of FIG.

In this embodiment, as shown in FIGS. 14 and 15, the configuration as a three-dimensional acceleration sensor is almost the same as that of the fourth embodiment, but the manufacturing process is different. That is, instead of the SIMOX method in the manufacturing process of the fourth embodiment, an n+ region is used as a region that is temporarily provided in the substrate and then removed. By introducing the n+ region, the etching process for the cavity etc. becomes more difficult than in the above case, but since the SIMOX method is expensive, the production cost can be reduced compared to the fourth embodiment.

Next, an example of the manufacturing process of the three-dimensional acceleration sensor of this embodiment will be explained using FIGS. 16 and 17.

(a) An n+ buried layer 83 on the main surface of the n-type substrate 1
is formed, and a first n-type epitaxial layer 3 is formed thereon. N+ buried layer 83 will be removed later. A p-type diffusion region 84 is formed in the first n-type epitaxial layer 3 to form a lower region of the cantilever beams 204, 304. Furthermore, an n+ diffusion region 86 is formed in the first n-type epitaxial layer 3. The n+ diffusion region 86 is later removed (FIG. 16(a))
.

(b) Cantilever beam 2 in p-type diffusion region 84
An n+ diffusion layer 87, which will be etched away later, is formed at the formation position of 04, 304 (FIG. 16(b)).

(c) First n-type epitaxial layer 4 is formed. Its thickness determines the thickness of the upper regions of cantilever beams 204, 304 and the support portion of cantilever beam 104. A p-type diffusion region 85 is formed in the upper portion of the p-type diffusion region 84 in the second n-type epitaxial layer 4 . The p-type diffusion region 85 forms the upper region of the cantilever beams 204, 304 (see FIG.
c), (d)).

(d) A p-type diffusion layer that will become the piezoresistor 61 is formed in a portion corresponding to the support portion of the cantilever beam 104. By etching, a first groove reaching the n+ buried layer 83 is formed, and this first groove is filled with oxide to form the oxide layer 68 (
65) (FIG. 16(e)).

(e) A second trench reaching the n+ buried layer 83 is formed by etching, and the second trench is filled with oxide 76. After forming a thin oxide film 77 by a light oxidation process, a nitride layer 21 is deposited and patterned to define the region of the cavity 5. Further, a light oxidation process is performed to form a thin oxide film 78, and a thin nitride film 79 is deposited thereon. The oxide film 78 and the nitride film 79 are patterned to form protective stripe regions on the oxide layers 65, 68 of the cantilevers 204, 304 (FIG. 17(a)).

(f) Deposit PSG 81 to form nitride layer 21
Fill the openings and flatten the surface. Next, a capping nitride layer 34 is deposited (FIG. 17(b)).

(g) Cavity 5 and each cantilever 104, 20
4,304 is formed by double etching. A first etch is performed with HF to remove oxides 76 and 81. The next etching is HF:HNO3:CH3C
The n+ regions 83, 86, and 87 are removed using an etching solution with an OOH mixing ratio of 1:3:8 (Fig. 17(c)).
).

As a modification of the fifth embodiment, SIMO
By combining the X method and the n+ region, it is also possible to form a removed portion by etching. In this case, the n+ buried layer 83 in the fifth embodiment is replaced with an oxide layer formed by the SIMOX method. However, the final structure when this modification is adopted is as shown in FIGS. 14 and 15 above.
This is the same as shown in . Therefore, the advantage of this modification is that the oxide layer on the lower part of the mass portion 104a of the cantilever beam 104 can be removed more easily than in the fifth embodiment, and that the supporting portion of the cantilever beam 104 can be removed easily. It can be easily formed thin.

[0066]

As explained above, according to the first invention, there is provided a three-dimensional acceleration sensor in which three detecting parts for detecting three-dimensional acceleration are formed on a semiconductor substrate, and each of the detecting parts Because it is composed of a cantilever beam consisting of a semiconductor layer that functions as a piezoresistor and an oxide film laminated on it,
Since each detection section can be configured on one chip, damage to the cantilever beam during wafer processing can be prevented. Further, a narrow gap can be formed easily and with good controllability, and the cantilever beam can be of an air damping type. Therefore, the structure is simple and costs can be reduced.

Further, according to the second invention, each detection section is
Since it is composed of a cantilever made of a semiconductor layer and an opposing wall that forms a capacitor between the cantilever, the air damping part can be used as the detection part component,
The structure can be further simplified.

[Brief explanation of drawings]

FIG. 1 is a plan view and a sectional view showing a first embodiment of a three-dimensional acceleration sensor according to the present invention.

FIG. 2 is a process diagram showing an example of the manufacturing process of the first embodiment.

FIG. 3 is a plan view and a sectional view showing a second embodiment of the invention.

FIG. 4 is a process diagram showing an example of the manufacturing process of the second embodiment.

FIG. 5 is a plan view showing a third embodiment of the invention.

6 is a cross-sectional view taken along line AA, line BB, and line CC in FIG. 5. FIG.

FIG. 7 is a process diagram showing an example of the manufacturing process of the third embodiment.

FIG. 8 is a plan view showing a fourth embodiment of the invention.

9 is a sectional view taken along line AA and line BB in FIG. 8. FIG.

FIG. 10 is a process diagram showing an example of the manufacturing process of the fourth embodiment.

FIG. 11 is a process diagram showing an example of the manufacturing process of the fourth embodiment.

FIG. 12 is a process diagram showing an example of the manufacturing process of the fourth embodiment.

FIG. 13 is a longitudinal sectional view showing a modification of the fourth embodiment.

FIG. 14 is a plan view showing a fifth embodiment of the invention.

15 is a cross-sectional view taken along line AA and line BB in FIG. 14. FIG.

FIG. 16 is a process diagram showing an example of the manufacturing process of the fifth embodiment.

FIG. 17 is a process diagram showing an example of the manufacturing process of the fifth embodiment.

FIG. 18 is a longitudinal cross-sectional view of a conventional acceleration sensor.

19 is a longitudinal cross-sectional view of the acceleration sensor of FIG. 18. FIG.

[Explanation of symbols]

10 Epitaxial semiconductor substrate 100, 101, 102, 103, 104, 200, 2
01,202,203,204,300,301,30
2,303,304 Cantilever beam

Claims (2)

[Claims] 1. A three-dimensional acceleration sensor in which three detecting sections for detecting three-dimensional acceleration are formed on a semiconductor substrate, wherein each detecting section includes a semiconductor layer that functions as a piezoresistor, and a semiconductor layer laminated thereon. A three-dimensional acceleration sensor comprising a cantilever made of an oxide film. 2. A three-dimensional acceleration sensor in which three detecting sections for detecting three-dimensional acceleration are formed on a semiconductor substrate, wherein each detecting section includes a cantilever made of a semiconductor layer and a cantilever made of a semiconductor layer; A three-dimensional acceleration sensor comprising a beam and an opposing wall that forms a capacitor.