JPH11135806A - Semiconductor pressure sensor and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor pressure sensor in which a recessed part can be formed simply and with good accuracy on the surface of a single-crystal silicon substrate, and to provide its manufacturing method. SOLUTION: A single-crystal silicon substrate, whose surface plane direction is a (100) plane is used as a single-crystal silicon substrate 1. A recessed part 3 is formed on the surface of the single-crystal silicon substrate 1. A diaphragm formation film is arranged on the surface of the single-crystal silicon substrate 1 so as to close the opening part of the recessed part 3. A through-hole 4 for etchant injection which is used to form the recessed part 3 is formed in the diaphragm formation film. The through-hole 4 is a slender cross shape which is extended to <110> directions of the single-crystal silicon substrate 1. In an etching operation to form the recessed part 3, a (111) plane is hard to be etched in the single-crystal substrate 1 on the (100) plane. As a result, in the <110> directions on the single-crystal silicon substrate 1, the etching operation is stopped by the (111) plane in end parts of the through-hole 4 for etchant injection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor pressure sensor and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, one method of forming a diaphragm and a concave portion (cavity) thereunder in a semiconductor pressure sensor has been proposed in Japanese Patent Publication No. 5-54708. This involves making a small hole in the film that will serve as an etching mask, immersing it in an etchant such as hydrofluoric nitric acid or an alkaline solution, and injecting the etchant through the hole to etch the underlying silicon substrate into a hollow shape. , Concave portions (cavities).

[0003]

However, since the size of the etched region expands with the etching time, there is a problem that it is difficult to control and the size of the region varies.

An object of the present invention is to provide a semiconductor pressure sensor capable of easily and accurately forming a concave portion on the surface of a single crystal silicon substrate, and a method of manufacturing the same.

[0005]

According to a first aspect of the present invention, there is provided a semiconductor pressure sensor, wherein a single crystal silicon substrate having a (100) plane orientation is used as a single crystal silicon substrate and a through hole for injecting an etchant. Is an elongated through hole extending continuously or intermittently in the <110> direction or the <100> direction of the single crystal silicon substrate.

With such a configuration, the (111) plane is hardly etched on the (100) plane single crystal silicon substrate during the etching for forming the concave portion. At the end of the elongated hole for etching liquid injection, (111)
Etching stops on the surface. Therefore, the etching shape dimensional accuracy of the concave portion, which has conventionally been a problem, can be ensured. That is, in the conventional structure, the etching liquid injection through-hole having a similar shape to the shape of the opening of the concave portion is formed, so that the opening of the concave portion becomes larger in proportion to the etching time. A desired recess can be obtained regardless of time.

Here, as described in claim 2, the elongated through hole extending in the <110> direction of the single crystal silicon substrate is:
It may be a cross, or as described in claim 3,
It is practically preferable that the elongated through-hole extending in the <100> direction of the single crystal silicon substrate has an X-shape.

According to the fourth aspect of the present invention, the diaphragm forming film is disposed on the single crystal silicon substrate having the (100) plane orientation of the surface, and the diaphragm forming film is formed on the single crystal silicon substrate. An elongated through hole extending continuously or intermittently in the 110> direction or the <100> direction is formed. Then, the surface of the single crystal silicon substrate is etched by injection of an anisotropic etching solution through the through-holes of the diaphragm forming film to form a concave portion.

At this time, since the (111) plane is difficult to be etched in the (100) plane single crystal silicon substrate, the (110) plane of the single crystal silicon substrate has (E) at the end of the elongated etching solution injection through-hole in the <110> direction. 111)
Etching stops on the surface. Therefore, the etching shape dimensional accuracy of the concave portion, which has conventionally been a problem, can be ensured. That is, in the conventional method, since the etching liquid injection through hole has a similar shape to the shape of the opening of the recess, the opening of the recess becomes larger in proportion to the etching time. A desired recess can be obtained regardless of time.

Thereafter, the through holes of the diaphragm forming film are closed. Here, the elongated through-hole extending in the <110> direction of the single-crystal silicon substrate may have a cross shape, as described in claim 5, or as described in claim 6, The elongated through-hole extending in the <100> direction
An X-shape is preferable for practical use.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a semiconductor pressure sensor according to the present embodiment, and FIG. 2 is a sectional view taken along line AA of FIG. In this pressure sensor, as shown in FIG. 2, a diaphragm is formed of a plasma silicon nitride film 2. In addition,
FIG. 1 shows the plasma silicon nitride film 2 and the backfill film 1 of FIG.
It is a top view of the silicon substrate 1 in a state where there is no 0 etc.

In FIGS. 1 and 2, a plasma silicon nitride film 2 is formed on the upper surface of a single crystal silicon substrate 1 having a (100) plane orientation and has a thickness of several hundred nm to several μm. In addition, a concave portion (cavity) 3 is formed on the surface of the single crystal silicon substrate 1, and the concave portion (cavity) 3 has an inverted quadrangular pyramid shape as shown in FIG. The opening of the recess 3 is closed by the plasma silicon nitride film (diaphragm forming film) 2. An etching solution injection hole 4 is formed in the plasma silicon nitride film 2 at the opening of the recess 3, and the recess 3 is formed by etching the substrate 1 when an etching solution is injected through the etching solution injection hole 4. It is.

As shown in FIGS. 1 and 3, the etching solution injection hole 4 is a cross-shaped elongated hole extending continuously in the <110> direction of the single crystal silicon substrate 1. Also, the width W of the elongated through hole 4 is 1 to several μm, and the length L of the long side of the cross is suitably several tens to several hundred μm. It corresponds to the long side of the opening.

As shown in FIGS. 1 and 2, a gauge 5 a,
5b, 5c and 5d are arranged, and the gauges 5a to 5d are made of single crystal silicon, polysilicon or the like. Gauge 5a-5
As for d, a change in strain applied to the plasma silicon nitride film 2 as a diaphragm can be extracted as a change in resistance value. Electrodes 6, 7, 8, and 9 are formed at both ends of each of the gauges 5a to 5d, and are connected to each other to form a bridge circuit. A backfill film 10 is formed on the plasma silicon nitride film 2, and the through holes 4 are closed by the backfill film 10. The backfill film 10 includes a silicon nitride film (SiN film) and a silicon oxide film (S
iO ₂ film), a polysilicon film, or the like. Since the through hole 4 to be backfilled has a size of several μm, the thickness of the backfill film 10 only needs to be large enough to seal it.

The diaphragm forming film is made of plastic.
In addition to the silicon nitride film 2, nitridation by LP-CVD
Silicon film (SiN film) or plasma silicon oxide film (S
iO _TwoAnd the like can be used in the same manner.

Next, a method for manufacturing the semiconductor pressure sensor thus configured will be described with reference to FIGS. First,
As shown in FIG. 4, a (100) oriented single crystal silicon substrate 1 is prepared, and a silicon nitride film 2 is formed on the surface thereof by plasma CVD.

As shown in FIG. 5, gauges 5a, 5a are provided in predetermined regions on the plasma silicon nitride film 2.
b, 5c, 5d and electrodes 6, 7, 8, 9
And further, the gauges 5a to 5d are covered with an etching resistant film (not shown). After that, the plasma silicon nitride film 2 is patterned by photoetching as shown in FIG. 7, and a hole for etching the underlying single crystal silicon substrate 1 is formed. As a result, a cross-shaped through hole 4 is formed.

After the cross holes 4 are formed in the plasma silicon nitride film 2 as described above, as shown in FIG. 6, the base single crystal silicon substrate 1 is passed through the holes 4 with an alkali solution (anisotropic etching solution). Is performed. As an etching solution, KOH or TMAH is used. As shown in FIG. 8 (an explanatory diagram of the progress of etching in the region Z1 in FIG. 7), the outermost portions P3 and P4 of the through holes 4 in the silicon nitride film 2 intersect with the (111) plane of the silicon substrate 1. The etching proceeds to P1, and the etching stops when the inverted quadrangular pyramid formed by this surface is formed. For this reason, the diaphragm and the concave portion 3 (cavity) are automatically formed with high precision without controlling the etching time.

More specifically, the shape of the etching solution injection hole 4 and the manner in which the etching proceeds by this will be described. A single-crystal silicon substrate 1 having a plane orientation of (100) is used and a cross-shaped through hole 4 extending in the <110> direction is provided. The surface of the underlying silicon substrate 1 is anisotropically etched from the through hole 4 with an alkaline solution. Then, as shown in FIGS. 8 and 9, at the intersection P2 of the cross-shaped through-hole 4, a surface having a high etch rate such as the (511) surface appears, and the side etch proceeds from P2 to P1. go. However, at the end portions P3 and P4 of the cross-shaped through hole 4, the (111) plane appears and the etching rate is very slow, so that the etching is substantially stopped. The side etching of the intersection P2 proceeds until reaching the point P1 on the extension of the (111) plane, and the etching is finally stopped in an inverted quadrangular pyramid shape surrounded by four (111) planes. Even if etching is continued in this state, there is almost no change in shape. As described above, the concave portion (cavity) 3 having a fixed shape can be obtained without controlling the etching time.

Returning to the description of the manufacturing method, after the etching for forming the concave portion 3 is completed, the substrate 1 is taken out of the etching solution, immersed in pure water and washed. After sufficient cleaning and drying, a film 10 for backfilling is deposited on the plasma silicon nitride film 2 by a method such as plasma CVD as shown in FIG. When this backfill is performed in a vacuum atmosphere,
The interior of the recess 3 (cavity) is evacuated, and a pressure reference chamber is formed.

As described above, this embodiment has the following features. (A) As a structure of a semiconductor pressure sensor, as shown in FIGS. 1 and 2, a single crystal silicon substrate having a (100) plane orientation is used as a single crystal silicon substrate 1.
The holes for etching solution injection are formed in the single crystal silicon substrate
110> The elongated cross-shaped through hole 4 continuously extending in the direction. Therefore, at the time of etching for forming the concave portion 3,
In the (100) plane single crystal silicon substrate 1, (11)
1) Since the surface is hardly etched, the etching stops at the (111) plane at the ends P3 and P4 of the elongated etching solution injection holes 4 in the <110> direction of the single crystal silicon substrate 1. Therefore, the etching shape dimensional accuracy of the concave portion, which has conventionally been a problem, can be ensured.

That is, as shown in FIG. 4, a plasma silicon nitride film (diaphragm forming film) 2 is disposed on a single crystal silicon substrate 1 having a (100) plane orientation.
As shown in FIG. 5, an elongated cross-shaped through hole 4 extending continuously in the <110> direction of the single crystal silicon substrate 1 is formed in the plasma silicon nitride film 2, and as shown in FIG. The surface of the single crystal silicon substrate 1 is etched by injecting an anisotropic etching solution through the through holes 4 of FIG. 2 to form the recesses 3, and the through holes 4 of the plasma silicon nitride film 2 are formed as shown in FIG. Blocked. Therefore, (100)
Since the (111) plane is hardly etched in the single-crystal silicon substrate 1, the <1
In the 10> direction, the etching stops at the (111) plane at the ends P3 and P4 of the etching solution injection hole 4. Therefore, the etching shape dimensional accuracy of the concave portion 3 which has conventionally been a problem can be ensured.

In the description so far, the cross-shaped through hole 4 extending in the <110> direction has been used as the etching solution injection through hole, but other than this, for example, as shown in FIG. The X-shaped through hole 15 may be extended. In this case, as shown in FIG. 3, the long side of the X-shaped through hole 15 corresponds to the diagonal length of the opening (square) of the recess 3.

Alternatively, as shown in FIG.
It may be a U-shaped through hole 16 extending in the direction, or an L-shaped through hole 17 extending in the <110> direction as shown in FIG.

In the case where the cross hole 4, the X-shaped hole 15, the U-shaped hole 16, or the L-shaped hole 17 are used as the holes for injecting the etching solution, the elongated holes 4 are formed in the plasma silicon nitride film 2. , 15, 16 and 17, when the surface of the underlying single crystal silicon substrate 1 is later etched, the plasma silicon nitride film 2 projects in a beam shape (eave shape),
At this time, since the intra-film stress of the plasma silicon nitride film 2 is released, the film 2 is easily warped. When the membrane 2 warps, finally the membrane 1
The process of vacuum-sealing the concave portion (cavity) 3 by depositing 0 and backfilling the through holes 4, 15, 16, 17 tends to be difficult. In order to solve this problem, FIG.
A through hole 18 as shown in FIG. In other words, the etching solution injection hole is not a continuous hole,
By arranging a large number of rectangular through-holes 18, the single-crystal silicon substrate 1 may be formed as an elongated through-hole extending intermittently in the <100> direction (or the <110> direction). That is, the elongated through-holes extending in the <100> direction (or the <110> direction) of the single-crystal silicon substrate 1 may be a series of points (square-shaped through-holes 18) other than lines. More specifically, one side of the rectangular through hole 18 is several μm (for example, 2 to 3 μm), and the pitch P is arranged at several μm (for example, 2 to 3 μm). Then, at the time of etching, as shown in FIG.
11) Inverted quadrangular pyramids are formed and connected to each other. As described above, the plasma silicon nitride film 2 is not divided by the through holes, and therefore, the underlying silicon can be etched in a flat state. (Second Embodiment) Next, a second embodiment will be described with reference to the first embodiment.
The following description focuses on the differences from this embodiment.

FIG. 15 is a sectional view of a semiconductor pressure sensor according to this embodiment. This sensor uses an SOI substrate. In FIG. 15, the plane orientation of the surface is (100).
A silicon layer (diaphragm forming film) 22 is formed on a single-crystal silicon substrate 20 with an insulating film 21 interposed therebetween.
On the silicon layer 22, a silicon oxide film 23 is formed. A silicon oxide film is used for the insulating film 21. The thickness of the insulating film 21 may be such that it can withstand as a mask when the single crystal silicon substrate 20 is etched later.
It is about 5 μm or more. The thickness of the silicon oxide film 23 is about 1 μm. The thickness of the silicon layer 22 is a thickness necessary for the diaphragm, for example, about 5 μm. Further, a recess 24 is formed in the single crystal silicon substrate 20. The laminated body of the insulating film 21, the silicon layer 22, and the silicon oxide film 23 has a through hole 25 for injecting an etching solution.
Are formed, and the through-hole 25 is formed as shown in FIGS.
13 is formed. The surface of the silicon layer 22 in the through hole 25 is covered with an oxide film 26, and the thickness of the oxide film 26 is about 0.5 to 1 μm. Further, boron diffusion layers 28 and 29 serving as piezo gauge resistors are formed in the surface layer of the silicon layer 22. The through-hole 25 is closed by the backfill film 27.

Next, a method of manufacturing the semiconductor pressure sensor thus configured will be described. First, as shown in FIG.
An SOI substrate is prepared. That is, the single crystal silicon substrate 2
A silicon layer 22 is formed on the substrate 0 with an insulating film 21 interposed therebetween. Then, boron diffusion layers 28 and 29 are formed in the surface layer of the silicon layer 22 by impurity diffusion. Further, FIG.
As shown in FIG. 5, a silicon oxide film 23 is formed on the surface of the silicon layer 22 by a method such as thermal oxidation or CVD.

Subsequently, as shown in FIG. 18, photo-etching of the same through-hole pattern as in the above-described embodiment for forming a diaphragm is performed to form through-holes 25 in the oxide film 23 and the silicon layer 22. In this case, dry etching is used to obtain a vertical cross section because the depth is deeper than the width.

Then, as shown in FIG. 19, an oxide film 30 is disposed on the surface of the silicon layer 22 at the through hole 25 by CVD or the like. Further, as shown in FIG. 20, the oxide film 26 on the side wall of the through hole 25 is left by anisotropic dry etching, and only the oxide films 21 and 30 at the bottom are removed. At this time, the oxide films 30 and 23 on the surface are also etched, but the thickness of the oxide film 23 formed first remains. Thus, an etching mask for silicon layer 22 covered with oxide films 21, 23, 26 is formed on single crystal silicon substrate 20.

Thereafter, as shown in FIG. 21, the substrate 20 is immersed in an alkaline solution such as KOH or TMAH. Then, the etching of the single crystal silicon substrate 20 proceeds from the through hole 25, and (111) is formed at the outermost periphery of the through hole 25 such as a cross.
Surface appears, etching stops, inverted quadrangular pyramid shaped recess 2
4 are formed.

Thereafter, the substrate is sufficiently washed with water and dried. Further, as shown in FIG. 15, a film 27 is formed in a vacuum or the like by a method such as CVD, and the through hole 25 is buried. In this way, a vacuum-sealed cavity (24) is formed.

Although the boron diffusion layers 28 and 29 serving as the piezo gauge resistance are formed before the etching for forming the recess 24, they can be performed after the etching. Further, it is necessary to arrange the gauge resistor at the edge of the diaphragm (the opening of the concave portion 24). The alignment of this pattern is performed by using the through-hole pattern 25 from the diaphragm edge (the end of the opening of the concave portion 24). Since the position is determined, it can be performed with high accuracy by matching the position. (Third Embodiment) Next, a third embodiment will be described with reference to the first embodiment.
The following description focuses on the differences from this embodiment.

FIG. 22 is a sectional view of a semiconductor pressure sensor according to this embodiment. This sensor uses a wafer (epiwafer) having an epitaxial layer. FIG.
2, an N-type epitaxial layer (diaphragm forming film) 41 is formed on a P-type single crystal silicon substrate 40 having a (100) plane orientation, and an epitaxial layer 4 is formed.
A silicon oxide film 42 is formed on 1. Since the epitaxial layer 41 is a diaphragm, the thickness of the epitaxial layer 41 is the thickness required for the diaphragm,
For example, it is 5 μm. A concave portion 43 is formed in the single crystal silicon substrate 40. In addition, an etching solution injection hole 44 is formed in the laminate of the N-type epitaxial layer 41 and the silicon oxide film 42, and the surface of the epitaxial layer 41 in the hole 44 is covered with the oxide film 45. Piezo gauge resistors (impurity diffusion layers) 47 and 48 are formed on the surface of the epitaxial layer 41. The through holes 44 are closed by the backfill film 46.

Next, a method of manufacturing the semiconductor pressure sensor having the above-described structure will be described. First, as shown in FIG.
An epi-wafer is prepared. That is, the N-type epitaxial layer 41 is grown on the P-type single crystal silicon substrate 40.
Further, piezo gauge resistors (impurity diffusion layers) 47 and 48 are formed on the epitaxial layer 41.

Then, as shown in FIG. 24, a silicon oxide film 42 is formed on the surface of the N-type epitaxial layer 41 by 0.5 to 1 μm by a method such as CVD. Further, FIG.
As shown in FIG. 5, a cross-shaped through-hole pattern similar to that of the above-described embodiment is formed on the silicon oxide film 42 by photoetching. Subsequently, the underlying epitaxial layer 41 is vertically anisotropically dry-etched using the through-hole pattern of the oxide film 42 as a mask.
Etch until it reaches zero.

Thereafter, as shown in FIG. 26, an oxide film 49 is formed to a thickness of about 0.5 to 1 μm by a method such as CVD.
It is desirable that the oxide film 49 has good step coverage such as a TEOS film.

Further, as shown in FIG. 27, oxide film 49 is etched by anisotropic dry etching. The etching is performed until the oxide film 49 at the bottom of the through hole 44 is removed. Thereby, the side wall of the through hole 44 and the epitaxial layer 41
Is masked by the oxide films 45 and 42.

Then, as shown in FIG. 28, the recess 43 is formed by immersing the platinum counter electrode 50 and the substrate 40 in an alkaline solution and performing electrochemical stop etching. KOH, TMAH, or the like is used as an etchant. When a positive potential is applied to the N-type epitaxial layer 41, the epitaxial layer 41 is not etched and the P-type silicon substrate 4 is not etched.
Only 0 is etched. As a result, a concave portion 43 (cavity) of an inverted quadrangular pyramid determined by a cross-shaped or similar through-hole pattern of the epi layer 41 is formed in the same manner as in the above embodiment.

Thereafter, as shown in FIG. 22, the through holes 44 are back-filled with the film 46. (Fourth Embodiment) Next, a fourth embodiment will be described with reference to the first embodiment.
The following description focuses on the differences from this embodiment.

FIG. 29 is a sectional view of a semiconductor pressure sensor according to this embodiment. In this sensor, the concave portion 66 is formed by performing electrochemical etching using an SOI wafer. When the SOI structure of FIG. 15 is used, the thickness of the silicon layer 22 becomes the diaphragm thickness,
This embodiment is suitable for a case where the thickness of the diaphragm is desired to be smaller than the thickness of the silicon layer 62 of SOI as shown in FIG. In this example, the thickness of the silicon layer 62 is 1
The active silicon layer (N-type diffusion layer) 65 serving as a diaphragm has a thickness of 4 μm.

In FIG. 29, a single crystal silicon substrate 60
Above, the plane orientation of the surface is (10
A silicon layer (single crystal silicon substrate) 62 of the 0) plane is formed, and a silicon oxide film 63 is formed on the silicon layer 62. A P-type impurity diffusion layer 64 is formed on the surface of silicon layer 62, and the depth of diffusion layer 64 is 5 μm.
I just need more. An N-type diffusion layer (diaphragm forming film) 65 is formed on the surface of the P-type impurity diffusion layer 64. Part of the P-type impurity diffusion layer 64 in the silicon layer 62 is removed to form a recess 66. An etching solution injection hole 67 is formed in the stacked body of the N-type diffusion layer 65 and the silicon oxide film 63. The through hole 67 is closed by the film 68. Further, a piezoresistive layer (not shown) is formed on the N-type diffusion layer 65.

Next, a method for manufacturing the semiconductor pressure sensor thus configured will be described. First, as shown in FIG.
An SOI substrate is prepared. That is, the single crystal silicon substrate 6
A single-crystal silicon layer 62 is formed on the substrate 0 via an insulating film 61.

Then, as shown in FIG. 31, by carrying out ordinary processes such as oxidation, photoetching, ion implantation, and thermal diffusion, the P-type impurity diffusion is performed to a region which is slightly outside the region on the surface where the diaphragm is formed. A layer 64 is formed.

Further, as shown in FIG. 32, an N-type diffusion layer 65 is formed in a region inside the P-type impurity diffusion layer 64 in the silicon layer 62 by using a similar process. Although the diffusion depth of the N-type diffusion layer 65 is 4 μm, to be precise, stop etching is performed in the N-type layer 65 at the time of the subsequent electrochemical etching. When the diaphragm thickness is 4 μm, it is necessary to make the thickness of the diaphragm 4 μm smaller by the depletion layer thickness.

Subsequently, as shown in FIG. 33, a silicon oxide film 63 is formed on the surface of the silicon layer 62 by a method such as CVD. In the silicon oxide film 63, a through-hole pattern such as a cross as in the above embodiment is formed by photoetching. Further, using the pattern of the oxide film 63 as a mask, the N-type diffusion layer 65 is etched vertically to the P-type impurity diffusion layer 64 by anisotropic dry etching. Further, the side wall of the through hole 67 is covered with an oxide film.

Subsequently, as shown in FIG. 34, the concave portion 66 is formed by immersing the platinum counter electrode 69 and the substrate 60 in an alkaline solution by electrochemical stop etching.
KOH, TMAH, or the like is used as an etchant. When a positive potential is applied to the N-type diffusion layer 65, the N-type diffusion layer 65 is not etched, and only the P-type impurity diffusion layer 64 and the underlying silicon layer 62 are etched. As a result, an inverted quadrangular pyramid recess 66 (cavity) determined by a cross-shaped or similar through-hole pattern is formed in the same manner as in the above embodiment.

As described above, by applying a voltage only to the N-type diffusion layer 65 at the time of electrochemical etching, the P-type impurity diffusion layer 64 of SOI thereunder is etched to form an inverted trapezoidal concave portion 66 (cavity). Is formed.

Thereafter, as shown in FIG. 29, the through holes 67 are back-filled with the film 68.

[Brief description of the drawings]

FIG. 1 is a plan view of a semiconductor pressure sensor according to a first embodiment.

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

FIG. 3 is a perspective view showing a concave portion.

FIG. 4 is a sectional view for explaining a manufacturing process of the semiconductor pressure sensor.

FIG. 5 is a cross-sectional view for explaining a manufacturing process of the semiconductor pressure sensor.

FIG. 6 is a cross-sectional view for explaining a manufacturing process of the semiconductor pressure sensor.

FIG. 7 is a plan view showing a mask pattern.

FIG. 8 is a diagram illustrating etching.

FIG. 9 is a diagram illustrating etching.

FIG. 10 is a plan view showing another example of a mask pattern.

FIG. 11 is a plan view showing another example of a mask pattern.

FIG. 12 is a plan view showing another example of a mask pattern.

FIG. 13 is a plan view showing another example of a mask pattern.

FIG. 14 is a diagram illustrating etching.

FIG. 15 is a sectional view of a semiconductor pressure sensor according to a second embodiment.

FIG. 16 is a cross-sectional view for explaining a manufacturing process of the semiconductor pressure sensor.

FIG. 17 is a cross-sectional view for explaining a manufacturing process of the semiconductor pressure sensor.

FIG. 18 is a sectional view for explaining a manufacturing process of the semiconductor pressure sensor.

FIG. 19 is a sectional view for explaining the manufacturing process of the semiconductor pressure sensor.

FIG. 20 is a sectional view for explaining the manufacturing process of the semiconductor pressure sensor.

FIG. 21 is a cross-sectional view for explaining a manufacturing process of the semiconductor pressure sensor.

FIG. 22 is a sectional view of a semiconductor pressure sensor according to a third embodiment.

FIG. 23 is a cross-sectional view for explaining a manufacturing process of the semiconductor pressure sensor.

FIG. 24 is a cross-sectional view for explaining a manufacturing process of the semiconductor pressure sensor.

FIG. 25 is a sectional view for explaining the manufacturing process of the semiconductor pressure sensor.

FIG. 26 is a cross-sectional view for explaining a manufacturing process of the semiconductor pressure sensor.

FIG. 27 is a cross-sectional view for explaining a manufacturing process of the semiconductor pressure sensor.

FIG. 28 is a cross-sectional view for explaining a manufacturing process of the semiconductor pressure sensor.

FIG. 29 is a sectional view of a semiconductor pressure sensor according to a fourth embodiment.

FIG. 30 is a sectional view for explaining the manufacturing process of the semiconductor pressure sensor.

FIG. 31 is a cross-sectional view for explaining a manufacturing process of the semiconductor pressure sensor.

FIG. 32 is a cross-sectional view for explaining a manufacturing process of the semiconductor pressure sensor.

FIG. 33 is a cross-sectional view for explaining the manufacturing process of the semiconductor pressure sensor.

FIG. 34 is a cross-sectional view for explaining a manufacturing process of the semiconductor pressure sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Single crystal silicon substrate, 2 ... Plasma silicon nitride film, 3 ... Depression, 4 ... Through-hole, 20 ... Single crystal silicon substrate,
Reference numeral 21: insulating film, 22: silicon layer, 23: silicon oxide film, 24: concave portion, 25: through hole, 40: single crystal silicon substrate, 41: epitaxial layer, 42: silicon oxide film,
43: concave portion, 44: through hole, 62: single crystal silicon layer, 6
3: silicon oxide layer, 65: diffusion layer, 66: recess, 67
… Through hole

Claims (6)

[Claims] A single-crystal silicon substrate; a recess formed on the surface of the single-crystal silicon substrate; a diaphragm-forming film formed on the surface of the single-crystal silicon substrate so as to cover an opening of the recess; A semiconductor pressure sensor comprising: a diaphragm forming film; and a through hole for injecting an etchant for forming the concave portion, wherein the single crystal silicon substrate has a surface orientation of (10).
In addition to using a single-crystal silicon substrate having a 0) plane, the through-hole for injecting the etching solution is formed with a <11
A semiconductor pressure sensor having an elongated through hole extending continuously or intermittently in a 0> direction or a <100> direction. 2. The elongated through-hole extending in the <110> direction of the single-crystal silicon substrate has a cross shape.
4. The semiconductor pressure sensor according to 1. 3. An elongated through-hole extending in the <100> direction of the single-crystal silicon substrate has an X-shape.
4. The semiconductor pressure sensor according to 1. 4. A step of arranging a diaphragm-forming film on a single-crystal silicon substrate having a (100) plane orientation on the surface;
Forming a long and thin through-hole extending continuously or intermittently in the 0> direction or the <100>direction; and injecting an anisotropic etching solution through the through-hole of the diaphragm-forming film to form a surface of the single-crystal silicon substrate. Forming a concave portion by etching the film, and closing a through hole of the diaphragm forming film. 5. An elongated through hole extending in a <110> direction of a single crystal silicon substrate has a cross shape.
3. The method for manufacturing a semiconductor pressure sensor according to claim 1. 6. The elongated through-hole extending in the <100> direction of the single-crystal silicon substrate has an X-shape.
3. The method for manufacturing a semiconductor pressure sensor according to claim 1.