JPH10111202A - Composite mesa structure, method of forming the same, and composite mesa diaphragm and pressure sensor using the same - Google Patents

Abstract

(57) [Summary] [Problem] A mesa angle can be kept constant.
Provided are a composite mesa structure and a method for forming the composite mesa structure, which can easily control the dimensions and shape of the mesa with high accuracy, and a composite mesa diaphragm and a pressure sensor using the same. SOLUTION: A first mesa 101 having a mesa shape in a convex state with respect to a substrate 12 is formed, and the first mesa 10 is formed.
At least one second mesa 102 having a concave mesa shape is formed on the top portion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a mesa structure and a method for forming the same, and a diaphragm and a pressure sensor using the same.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view for explaining a conventional pressure sensor using a diaphragm.

[0003] Conventionally, as a pressure sensor using a diaphragm having a mesa structure of this type, for example, Japanese Utility Model Application Laid-Open No. 4-1 / 4-1
No. 33458 (Name of device: pressure sensor, applicant:
OMRON Corporation, filing date: December 11, 1992) (see FIG. 4).

In the diaphragm shown in FIG. 4, a thin portion 2 is formed at the center of a single-crystal silicon substrate 1, and further a thin portion 2 is formed.
Has a mesa 2 in which a thick portion 7 is formed at the center.

A pressure sensor A using such a diaphragm includes a pressure-sensitive chip formed by joining a glass plate and a diaphragm via a cavity 4,
The lower surface of the diaphragm is fixed to the locking member 8, and the locking member 8 has a structure in which a projection 9 facing the thick portion 7 and a through hole 8 a penetrating in the thickness direction of the substrate are provided at a predetermined interval. Was.

In order to detect the capacitance formed between the substrate 3 and the upper surface of the diaphragm, a pair of electrodes 5 and 5 for detecting the capacitance are provided on each of the lower surface of the substrate 3 and the lower surface of the diaphragm. Was provided.

In the pressure sensor A having such a configuration, the diaphragm is deformed when the pressure of the portion to be measured is transmitted into the cavity 4 through the through hole 6, and the amount of the deformation is determined by using the electrodes 5 and 5. Was detected.

FIGS. 5A to 5H are process diagrams for explaining a method of forming a diaphragm used in the conventional pressure sensor A.

In the diaphragm having such a configuration, the diaphragm is bent due to the weight of the mesa 2, and the characteristics (for example, offset and span) of the pressure sensor are varied. there is a possibility.

Furthermore, due to the weight of the mesa 2, the pressure sensor functions as a kind of acceleration sensor, and there is a possibility that an unnecessary change in capacitance with respect to mechanical vibration as a disturbance may occur.

Further, since unnecessary vibration is generated in response to mechanical vibration which is a disturbance, there is a possibility that the mechanical strength of the diaphragm is reduced.

In order to solve such a problem, in the conventional pressure sensor A, in order to reduce the weight of the mesa 2, a diaphragm forming method for forming the thin mesa 2 is implemented. (FIGS. 5A to 5H)
reference).

The steps shown in FIGS. 5A to 5C are (10)
0) A mask material is formed on a silicon substrate (FIG. 5)
(A)) A pattern corresponding to the top of the mesa 2 is applied to this mask material using photolithography to form a mesa mask (FIG. 5 (b)), and anisotropic etching of the (100) silicon substrate according to the patterning To form a mesa 2 (FIG. 5C), which shows a first etching step.

FIG. 5D shows a step of removing only the mask material on the top of the mesa 2.

5E to 5H show a second etching step of performing anisotropic etching on the mesa 2 to adjust the thickness of the mesa 2 subsequent to the first etching step. ing.

The top of the mesa 2 is formed with a (100) crystal orientation plane, and the side face is formed with a (111) crystal orientation plane.

[0017]

However, in such a conventional diaphragm forming method, when only the mask material on the top of the mesa 2 is peeled off in the second etching step (step of FIG. 5D), A surface having an etching rate higher than that of the (100) crystallographic plane appears from the corner (step (FIG. 5E)), and as the etching process proceeds, the (100) crystallographic plane at the top and (111) at the side are formed. 5) Both crystal orientation planes are etched (step of FIG. 5 (f)).

If such an etching step is continued, the (111) crystal orientation plane on the side surface of the mesa 2 will be composed of only the plane having the above-mentioned high etching rate (FIG. 5 (g)). Process).

When the etching process is further continued, FIG.
As shown in the step (h), the bottom area of the mesa 2 is reduced at an etching rate several times that at which the (100) crystal orientation plane at the top and the (100) crystal orientation plane around the diaphragm are etched. As a result, the mesa dimension d decreases, and as a result, the angle of the mesa 2 (hereinafter, abbreviated as the mesa angle) is kept constant, and the dimension and shape of the mesa 2 are accurately controlled (that is, the dimension and shape). It is difficult to maintain controllability).

Further, since the etching rate in the conventional second etching step largely depends on variations in etching conditions (for example, temperature and concentration of the etchant), the mesa angle is maintained and the controllability of the size and shape is maintained. There was a technical problem that it was more difficult to do.

An object of the present invention is to solve such a conventional problem. In particular, a mask material is formed on a substrate, and patterning corresponding to the top of the first mesa is performed using photolithography. A first mesa mask is formed on the mask material to form a first mesa by performing anisotropic etching of the substrate in accordance with patterning, and a first etching step is followed by a first etching step on the top of the first mesa. Forming a second mesa mask by forming a mask material on the peripheral portion on the top of the first mesa by performing patterning according to the top of the second mesa using photolithography, A second etching step of forming a second mesa by performing anisotropic etching of the first mesa in accordance with patterning, thereby providing a (100) crystal orientation plane at the top and a periphery of the diaphragm. As a result, it is possible to prevent the mesa dimension d from being reduced by preventing the mesa bottom area from decreasing at an etching rate several times that at which the (100) crystal orientation plane is etched, thereby maintaining the mesa angle constant. It is an object of the present invention to provide a method for forming a composite mesa structure that makes it easy to accurately control the dimensions and shape of the semiconductor device (that is, to maintain the controllability of the dimensions and shape).

Further, the mesa angle is kept constant and the controllability of the dimensions and the shape is maintained without being affected by the change of the etching rate caused by the variation of the etching conditions (for example, the temperature and concentration of the etchant). It is an object of the present invention to provide a method for forming a composite mesa structure that enables the formation of a composite mesa structure.

Also, a first mesa having a mesa shape in a convex state with respect to the substrate is formed, and a second mesa having a mesa shape in a concave state is formed on the top of the first mesa with at least one mesa on the top. And (10) crystal orientation planes at the top and (10) around the diaphragm.
0) It is possible to prevent a decrease in the mesa dimension d by preventing the mesa bottom area from decreasing at an etching rate several times that at which the crystal orientation plane is etched. As a result, the mesa angle can be kept constant, and the mesa angle can be maintained. Using a composite mesa structure, a composite mesa diaphragm having a composite mesa structure, and a composite mesa diaphragm, which facilitates accurate control of dimensions and shapes (that is, maintaining controllability of dimensions and shapes) It is an object to provide a configured pressure sensor.

Furthermore, the mesa angle is kept constant and the controllability of the size and shape is maintained without being affected by the change of the etching rate due to the variation of the etching conditions (for example, the temperature and concentration of the etchant). It is an object to provide a composite mesa structure, a composite mesa diaphragm having the composite mesa structure, and a pressure sensor configured using the composite mesa diaphragm.

[0025]

According to the first aspect of the present invention, a first mesa 101 having a mesa shape that is convex with respect to a substrate 12 is formed, and a top portion B of the first mesa 101 is formed. And the second mesa 10 having a concave mesa shape
2 is a composite mesa structure 30, wherein at least one or more of them are formed on the top B.

According to the first aspect of the present invention, each of the mesa angles θ1 and θ2 can be adjusted without being affected by a change in an etching rate caused by a variation in etching conditions (for example, temperature or concentration of an etchant). This has the effect of realizing a composite mesa structure 30 that can be kept constant and that the controllability of size and shape can be maintained.

According to the composite mesa structure 30, the first mesa 101 and the second mesa 1 of the composite mesa diaphragm 10 are formed.
02 while maintaining the mesa angles θ1 and θ2 constant,
With the controllability of the dimensions and shapes of the mesas 101 and the second mesas 102 maintained, there is an effect that the composite mesa structure 30 capable of reducing the weight of the composite mesa diaphragm 10 can be realized.

As described above, the weight of the composite mesa diaphragm 10 can be reduced while maintaining the dimensional controllability. As a result, the composite mesa diaphragm 10 can be prevented from being bent, and the characteristics of the pressure sensor 20 caused by this can be avoided. There is an effect that the composite mesa structure 30 that can avoid the occurrence of variations in (for example, offset and span) can be realized.

Further, the first mesa 101 and the second mesa 102
As a result, it is possible to avoid the phenomenon that the pressure sensor 20 works as a kind of acceleration sensor, and as a result, useless change of the capacitance due to mechanical vibration which is a disturbance. The composite mesa structure 30 can be realized.

Further, as a result of avoiding unnecessary vibration caused by mechanical vibration as a disturbance, a composite mesa structure 30 capable of avoiding unnecessary reduction in mechanical strength of the composite mesa diaphragm 10 is realized. It has the effect of being able to do it.

According to a second aspect of the present invention, in the method of forming the composite mesa structure 30 according to the first aspect, the mask material 11 is formed on the substrate 12 so as to correspond to the top B of the first mesa 101. Performing a patterning on the mask material 11 using photolithography to form a first mesa mask 14 and performing anisotropic etching of the base according to the patterning to form the first mesa 101; Subsequent to the first etching step, a mask material 11 is formed on the top B of the first mesa 101,
The patterning according to the top B of the mesa 102 is performed using photolithography to form the mask material 11 on the peripheral portion on the top B of the first mesa 101 to form the second mesa mask 16, and according to the patterning. The first mesa 101 is anisotropically etched to form the second mesa 10.
And a second etching step of forming a composite mesa structure 30.

According to the second aspect of the present invention, the second etching step of providing the second mesa mask 16 on the peripheral portion on the top portion B of the first mesa 101 is performed, in addition to the effect of the first aspect. By providing the second mesa 102 on the top portion B of the first mesa 101, the first mesa 101 has a first (100) crystal orientation plane at the top B and a (100) crystal orientation surface around the diaphragm at an etching rate several times higher than the first portion. As a result of preventing the decrease in the mesa size d by preventing the bottom area of the mesa 101 from decreasing, it becomes possible to keep each of the mesa angles θ1 and θ2 constant, and to precisely control the size and shape of the mesa. (In other words, the effect of maintaining the controllability of the size and shape) is obtained.

Furthermore, each of the mesa angles θ1 and θ2 is kept constant without being affected by a change in the etching rate due to a variation in etching conditions (for example, the temperature and concentration of the etchant), There is an effect that a composite mesa structure 30 capable of maintaining controllability can be realized.

According to such a composite mesa structure 30, the first mesa 101 and the second mesa 1 of the composite mesa type diaphragm 10 are formed.
02 while maintaining the mesa angles θ1 and θ2 constant,
With the controllability of the dimensions and shapes of the mesas 101 and the second mesas 102 maintained, there is an effect that the composite mesa structure 30 capable of reducing the weight of the composite mesa diaphragm 10 can be realized.

As described above, the weight of the composite mesa diaphragm 10 can be reduced while maintaining the dimensional controllability. As a result, the bending of the composite mesa diaphragm 10 can be avoided, and the characteristics of the pressure sensor 20 caused by this can be avoided. There is an effect that the composite mesa structure 30 that can avoid the occurrence of variations in (for example, offset and span) can be realized.

Further, the first mesa 101 and the second mesa 102
As a result, it is possible to avoid the phenomenon that the pressure sensor 20 works as a kind of acceleration sensor, and as a result, useless change of the capacitance due to mechanical vibration which is a disturbance. The composite mesa structure 30 can be realized.

Further, as a result of avoiding unnecessary vibration caused by mechanical vibration, which is a disturbance, a composite mesa structure 30 capable of avoiding unnecessary reduction in mechanical strength of the composite mesa diaphragm 10 is realized. It has the effect of being able to do it.

According to a third aspect of the present invention, there is provided a composite mesa diaphragm 1 using the composite mesa structure 30 according to the first aspect.
0, having the composite mesa structure 30 on a substrate,
This is a composite mesa diaphragm 10.

According to the third aspect of the present invention, the composite mesa type diaphragm 10 is formed by such a composite mesa structure 30.
Of the first mesa 101 and the second mesa 102 are kept constant, and the first mesa 101 and the second mesa 102 are kept constant.
With the controllability of the size and shape of the mesa 102 maintained, the composite mesa diaphragm 10 can be realized in which the weight of the composite mesa diaphragm 10 can be reduced.

According to a fourth aspect of the present invention, there is provided a pressure sensor using the composite mesa diaphragm according to the third aspect.
In the pressure sensor 20, which detects a deformation amount generated by a diaphragm stretched in the cavity 204 in accordance with a change in pressure generated in the cavity 204 and detects a pressure change in the cavity 204, A pressure sensor 20 comprising the composite mesa diaphragm 10 as a diaphragm.

According to the fourth aspect of the present invention, the use of the composite mesa type diaphragm 10 which can be reduced in weight can avoid the bending of the composite mesa type diaphragm 10 and can be caused by this. This makes it possible to realize the pressure sensor 20 that can avoid the occurrence of variations in the characteristics (eg, offset and span) of the pressure sensor 20.

Further, the first mesa 101 and the second mesa 102
As a result, it is possible to avoid the phenomenon that the pressure sensor 20 works as a kind of acceleration sensor, and as a result, useless change of the capacitance due to mechanical vibration which is a disturbance. The pressure sensor 20 which can avoid the problem can be realized.

Further, as a result of avoiding unnecessary vibration caused by mechanical vibration which is a disturbance, the pressure sensor 20 which can avoid unnecessary decrease in mechanical strength of the composite mesa diaphragm 10 is realized. It has the effect that it can be done.

[0044]

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

First, an embodiment of the composite mesa diaphragm 10 will be described.

FIG. 1A is a bottom view for explaining a composite mesa diaphragm 10 having a composite mesa structure 30. FIG. 1B is a bottom view of the composite mesa diaphragm shown in FIG. It is AA sectional drawing of the diaphragm 10. FIG.

The composite mesa structure 30 corresponds to the A-
As shown in A sectional view, a substrate 1 using single crystal silicon
A first mesa 101 having a mesa shape in a convex state with respect to 2 is formed, and a second mesa 102 having a mesa shape in a concave state is formed on the top B with respect to the top B of the first mesa 101. It is configured.

Further, a composite mesa structure 30 to be described later is formed on a substrate (specifically, single crystal silicon) of the composite mesa diaphragm 10 of the present embodiment shown in FIGS. 1 (a) and 1 (b). The composite mesa structure 30 described above is formed.

As described above, the second mesa 101 is provided on the top B of the first mesa 101.
By providing the mesa 102, each of the mesa angles θ1 and θ2 can be kept constant without being affected by a change in the etching rate due to a variation in etching conditions (for example, the temperature and concentration of the etchant). -The composite mesa structure 30 capable of maintaining the controllability of the shape can be realized.

According to such a composite mesa structure 30, the mesa angles θ1 and θ2 of the first mesa 101 and the second mesa 102 of the composite mesa diaphragm 10 are kept constant, and
With the controllability of the size and shape of the first mesa 101 and the second mesa 102 maintained, the composite mesa structure 30 capable of reducing the weight of the composite mesa diaphragm 10 can be realized. Play.

As described above, the weight of the composite mesa diaphragm 10 can be reduced while maintaining the dimensional controllability. As a result, the composite mesa diaphragm 10 can be prevented from bending, and the characteristics of the pressure sensor 20 due to this can be avoided. There is an effect that the composite mesa structure 30 that can avoid the occurrence of variations in (for example, offset and span) can be realized.

Further, the first mesa 101 and the second mesa 102
As a result, it is possible to avoid the phenomenon that the pressure sensor 20 works as a kind of acceleration sensor, and as a result, useless change of the capacitance due to mechanical vibration which is a disturbance. The composite mesa structure 30 can be realized.

Further, as a result of avoiding unnecessary vibration caused by mechanical vibration as a disturbance, a composite mesa structure 30 capable of avoiding unnecessary reduction in mechanical strength of the composite mesa diaphragm 10 is realized. It has the effect of being able to do it.

Next, a method for forming the composite mesa structure 30 in which the composite mesa diaphragm 10 is formed will be described with reference to the drawings.

FIGS. 2A to 2E are process diagrams for explaining a method of forming the composite mesa structure 30 according to the present invention. FIG. FIG. 2 is a cross-sectional view for explaining a composite mesa diaphragm 10 used.

2 (a) → FIG. 2 (b) → FIG. 2 (c) shows the first etching step, and FIG. 2 (d) → FIG.
The step (e) shows the second etching step.

The first etching step is a step of forming the mask material 11 on the single crystal silicon substrate 12 (see FIG. 2A), and following this step, the top part B of the first mesa 101 is used. A step of forming the first mesa mask 14 by performing patterning on the mask material 11 using photolithography (see FIG. 2B), and following this step, the difference in the plane orientation (100) of the silicon substrate 12 is determined in accordance with the patterning. Forming a first mesa 101 by performing anisotropic etching (see FIG. 2C).

As a result, the first mesa 1 having the mesa angle θ1
01 is formed. In such a first mesa 101,
The top portion B is formed with a (100) crystal orientation plane, and the side face is (1).
11) It is formed on the crystal orientation plane.

The second etching step is a step of adjusting the weight of the first mesa 101 by performing anisotropic etching on the first mesa 101 subsequent to the first etching step.
A mask material 11 is formed on the top portion B of the mesa 101, and patterning corresponding to the top portion B of the second mesa 102 is performed by using photolithography to form a mask material 11 on the peripheral portion of the top portion B of the first mesa 101. To form the second mesa mask 16
(See FIG. 2D), and a step of forming the second mesa 102 by performing anisotropic etching of the first mesa 101 according to patterning following this step (see FIG. 2D).
(See (e)).

As a result, a second mesa 102 having a mesa angle θ2 as shown in FIG. 2 (f) is formed. In such a second mesa 102, the top B is formed with the (100) crystal orientation plane, and the side face is formed with the (111) crystal orientation plane.

As described above, according to the present forming method, the second etching step of providing the second mesa mask 16 at the peripheral portion on the top B of the first mesa 101 is performed.
In addition to the effects described in (1), the first mesa 101 is etched at several times the etching rate of the surface of the top B (100) and the (100) crystal orientation surface around the composite mesa diaphragm 10.
As a result, it is possible to keep the mesa dimensions θ1 and θ2 constant and to control the size and shape of the mesa with high precision (rules). That is, it is possible to realize a method of forming the composite mesa structure 30 that facilitates the control of the size and shape).

Further, each of the mesa angles θ1 and θ2 is kept constant without being affected by a change in the etching rate due to a variation in the etching conditions (for example, the temperature and concentration of the etchant). There is an effect that a method for forming the composite mesa structure 30 capable of maintaining controllability can be realized.

Next, an embodiment of the pressure sensor 20 using the composite mesa diaphragm 10 will be described with reference to the drawings.

FIG. 3 is a sectional view for explaining a pressure sensor 20 using the composite mesa diaphragm 10.

The pressure sensor 20 detects the amount of deformation generated by the composite mesa type diaphragm 10 stretched in the cavity 204 in accordance with the change in pressure generated in the cavity 204, and detects the pressure change in the cavity 204. Has the function of detecting

The composite mesa diaphragm 10 shown in FIG.
Has a structure in which a thin portion is formed in the center of a single crystal silicon substrate 12, a first mesa 101 is formed in the center of a thin portion 202, and a second mesa 102 is formed in the center of the first mesa 101. Having.

Further, such a composite mesa diaphragm 1
The pressure sensor 20 using 0 has a pressure-sensitive chip formed by bonding a glass plate 211 and a composite mesa-type diaphragm 10 via a cavity 204, and the lower surface of the composite mesa-type diaphragm 10 is The protrusion 209 is fixed to the locking member 208 and faces the first mesa 101 at a predetermined interval, and the through hole 2 penetrates in the thickness direction of the substrate 12.
10 has a structure provided on the locking member 208.

In order to detect the capacitance formed between the substrate 12 and the upper surface of the composite mesa-type diaphragm 10, each of the lower surface of the substrate 12 and the lower surface of the composite mesa-type diaphragm 10 has a capacitance detecting capacitance. Are provided.

In the pressure sensor 20 having such a configuration, when the pressure of the measured portion is transmitted to the cavity 204 through the through hole 206, the composite mesa diaphragm 10 is deformed, and the amount of this deformation is measured by the electrode 205. , 205 can be detected.

According to the pressure sensor 20 having such a configuration, by using the composite mesa diaphragm 10 which can be reduced in weight, the composite mesa diaphragm 10 is used.
Of the pressure sensor 2 caused by the deflection of the pressure sensor 2
There is an effect that it is possible to realize the pressure sensor 20 that can avoid occurrence of variation in the characteristic of 0 (for example, offset or span).

Further, the first mesa 101 and the second mesa 102
As a result, it is possible to avoid the phenomenon that the pressure sensor 20 works as a kind of acceleration sensor, and as a result, useless change of the capacitance due to mechanical vibration which is a disturbance. The pressure sensor 20 which can avoid the problem can be realized.

Further, as a result that unnecessary vibration caused by mechanical vibration, which is a disturbance, can be avoided, a pressure sensor 20 that can avoid unnecessary reduction in mechanical strength of the composite mesa diaphragm 10 is realized. It has the effect that it can be done.

[0073]

According to the first aspect of the present invention, by providing the second mesa on the top of the first mesa, the (10) of the top is provided.
0) The bottom area of the first mesa can be prevented from decreasing at an etching rate several times that at which the (100) crystal orientation plane around the diaphragm is etched and the decrease in the mesa dimension d can be avoided. It is possible to maintain each of θ1 and θ2 constant, and to precisely control the size and shape of the mesa (that is, to maintain the controllability of the size and shape).
The effect that becomes easy is produced.

Further, each of the mesa angles θ1 and θ2 is kept constant without being affected by a change in the etching rate due to a variation in etching conditions (for example, the temperature and concentration of the etchant). There is an effect that a composite mesa structure capable of maintaining controllability can be realized.

According to such a composite mesa structure, the mesa angles θ 1 and θ 2 of the first mesa and the second mesa of the composite mesa diaphragm are obtained.
Realizing a composite mesa structure capable of reducing the weight of the composite mesa-type diaphragm while maintaining the first and second mesas constant while controlling the dimensions and shapes of the first and second mesas. It has the effect that it can be done.

As described above, the weight reduction of the composite mesa diaphragm can be realized while maintaining the dimensional controllability. As a result, the bending of the composite mesa diaphragm is avoided, and the characteristics of the pressure sensor (for example, Offset and span)
This has the effect of realizing a composite mesa structure that can avoid the occurrence of variations in the structure.

Furthermore, as a result of the weight reduction of the first mesa and the second mesa while maintaining the dimensional controllability, the phenomenon that the pressure sensor works as a kind of acceleration sensor can be avoided. There is an effect that a composite mesa structure capable of avoiding unnecessary change in capacitance due to vibration can be realized.

Further, a composite mesa structure capable of avoiding unnecessary reduction in mechanical strength of the composite mesa diaphragm as a result of avoiding unnecessary vibration due to mechanical vibration as a disturbance can be realized. It has the effect that it can be done.

According to the second aspect of the present invention, the second etching step of providing the second mesa mask on the peripheral portion on the top of the first mesa depends on the first aspect. By providing the second mesa on the top of the mesa, the (100) crystal orientation plane on the top and the (100) crystal around the diaphragm
As a result, it is possible to prevent the bottom area of the first mesa from decreasing at an etching rate several times that at which the crystal orientation plane is etched, thereby avoiding a decrease in the mesa dimension d. As a result, each of the mesa angles θ1 and θ2 can be kept constant. This makes it possible to easily control the size and shape of the mesa with high accuracy (that is, to maintain the controllability of the size and shape).

Further, each of the mesa angles θ 1 and θ 2 is kept constant without being affected by a change in the etching rate due to a variation in etching conditions (for example, the temperature and concentration of the etchant), There is an effect that a composite mesa structure capable of maintaining controllability can be realized.

According to such a composite mesa structure, the mesa angles θ 1 and θ 2 of the first mesa and the second mesa of the composite mesa diaphragm are obtained.
Realizing a composite mesa structure capable of reducing the weight of the composite mesa-type diaphragm while maintaining the first and second mesas constant while controlling the dimensions and shapes of the first and second mesas. It has the effect that it can be done.

As described above, it is possible to reduce the weight of the composite mesa diaphragm while maintaining the dimensional controllability. As a result, it is possible to avoid the bending of the composite mesa diaphragm and to obtain the characteristics of the pressure sensor (for example, Offset and span)
This has the effect of realizing a composite mesa structure that can avoid the occurrence of variations in the structure.

Further, the first and second mesas can be reduced in weight while maintaining the dimensional controllability. As a result, the phenomenon that the pressure sensor works as a kind of acceleration sensor can be avoided. There is an effect that a composite mesa structure capable of avoiding unnecessary change in capacitance due to vibration can be realized.

Further, it is possible to realize a composite mesa structure in which unnecessary vibration caused by mechanical vibration as a disturbance can be avoided, and as a result, unnecessary reduction in mechanical strength of the composite mesa diaphragm can be avoided. It has the effect that it can be done.

According to the third aspect of the present invention, the first mesa and the second mesa angles θ1 and θ2 of the composite mesa diaphragm are kept constant, and the first mesa angle is kept constant. With the controllability of the size and shape of the first mesa and the second mesa maintained, an effect is obtained that a composite mesa diaphragm capable of reducing the weight of the composite mesa diaphragm can be realized.

According to the fourth aspect of the present invention, the use of the composite mesa diaphragm, which can be reduced in weight, avoids the bending of the composite mesa diaphragm.
There is an effect that it is possible to realize a pressure sensor that can avoid the occurrence of variations in the characteristics (for example, offset and span) of the pressure sensor due to this.

Furthermore, as a result of the weight reduction of the first mesa and the second mesa while maintaining the dimensional controllability, the phenomenon that the pressure sensor works as a kind of acceleration sensor can be avoided. There is an effect that a pressure sensor that can avoid unnecessary change in capacitance due to vibration can be realized.

Further, it is possible to realize a pressure sensor capable of avoiding useless vibration caused by mechanical vibration as a disturbance, thereby preventing useless reduction in mechanical strength of the composite mesa diaphragm. It has the effect of being able to.

[Brief description of the drawings]

FIG. 1 (a) is a bottom view for explaining a composite mesa diaphragm using a composite mesa structure, and FIG. 1 (b) is a composite mesa diaphragm shown in FIG. 1 (a). It is AA sectional drawing of.

FIGS. 2A to 2E are process diagrams for explaining a method for forming a composite mesa structure according to the present invention.
(F) is a sectional view for explaining a composite mesa diaphragm using a composite mesa structure.

FIG. 3 is a cross-sectional view for explaining a pressure sensor using a composite mesa diaphragm.

FIG. 4 is a cross-sectional view for explaining a conventional pressure sensor using a diaphragm.

5 (a) to 5 (h) are process diagrams for explaining a method of forming the diaphragm of FIG.

[Explanation of symbols]

 Reference Signs List 10 composite mesa diaphragm 11 mask material 101 first mesa 102 second mesa 12 substrate 14 first mesa mask 16 second mesa mask 20 pressure sensor 204 cavity 30 composite mesa structure θ1 mesa angle of first mesa θ2 mesa angle of second mesa

Claims (4)

[Claims] A first mesa having a mesa shape in a convex state with respect to a substrate is formed, and a second mesa having a mesa shape in a concave state is formed on the top with respect to the top of the first mesa. A composite mesa structure, wherein at least one or more are formed and configured. 2. A method for forming a composite mesa structure, comprising: forming a mask material on a substrate; and performing patterning according to the top of the first mesa on the mask material using photolithography. Forming a first mesa by forming a first mesa mask and performing anisotropic etching of the base in accordance with the patterning; forming a mask material on top of the first mesa following the first etching step; The second mesa mask is formed by performing patterning according to the top of the second mesa using photolithography to form a mask material on a peripheral portion on the top of the first mesa, and forming a second mesa mask. A second etching step of forming the second mesa by performing anisotropic etching of the first mesa according to patterning. Structure forming method. 3. The composite mesa diaphragm according to claim 1, wherein the composite mesa structure is provided on a base. 4. A pressure sensor for detecting a change in pressure generated in a cavity by detecting a deformation amount generated by a diaphragm stretched in the cavity according to a change in pressure generated in the cavity, wherein the diaphragm includes: The pressure sensor using a composite mesa diaphragm according to claim 3, wherein the pressure sensor is configured using the composite mesa diaphragm.