JPH04274372A - Manufacture of silicon diaphragm - Google Patents

Abstract

PURPOSE:To provide the manufacture of a silicon diaphragm forming the thickness of a diaphragm with excellent dimensional accuracy by utilizing SOI structure while having an overpressure protective function. CONSTITUTION:A silicon oxide film is formed onto a silicon substrate, a required position is removed through etching while the film is left in a latticed shape, and the epitaxial layers of silicon are grown on the substrate and the film. Silicon oxide film are formed onto the surface of a selective epitaxial layer and the surface of the silicon substrate, a silicon nitride film is shaped onto the surfaces of the silicon oxide films, an etching hole reaching the silicon oxide film is formed, and the silicon oxide films are removed through etching. The substrate and the selective epitaxial layer are oxidized through the etching hole, a sensor element detecting displacement is formed onto the external surface of the selective epitaxial layer, an oxidized section is taken off through etching, and the silicon nitride film and the silicon oxide films are removed through etching.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a silicon diaphragm that uses an SOI structure to form a diaphragm with high dimensional accuracy and has an overpressure protection function.

0002

2. Description of the Related Art FIG. 13 is a diagram illustrating the configuration of a conventional example that has been commonly used. In the figure, 1 is a silicon substrate, and 2 is a silicon diaphragm formed on the substrate 1 by a recess 3. 4 is silicon diaphragm 2
This is a sensor element that detects the displacement of. In this case, piezoresistive elements are used.

[0003] Such a silicon diaphragm is manufactured as follows. FIGS. 14 to 20 are explanatory drawings for manufacturing main parts of a conventional example that has been generally used. (1) As shown in FIG. 14, a sensor element 102 for detecting displacement of a diaphragm is formed on one side of a silicon substrate 101. (2) As shown in FIG. 15, silicon oxide films 103 are formed on both sides of the silicon substrate 101. (3) As shown in FIG. 15, a silicon nitride film 104 is formed on the surface of the silicon oxide film 103. (4) As shown in FIG. 16, the sensor element 1 on the substrate 101
Required portions of the silicon oxide film 103 and the silicon nitride film 104 on the surface opposite to the surface on which 02 is formed are removed by etching to form an etching injection hole 105. 106 indicates a resist. (5) As shown in FIG. 17, an etching solution is injected through the etching injection hole 105 to perform anisotropic etching of the substrate 101. (6) As shown in FIG. 18, after a certain period of time has passed, the thickness t of the silicon diaphragm portion 108 is measured. (7) As shown in Figure 19, silicon diaphragm part 1
If the thickness of 08 is insufficient, additional etching is performed. (8) Repeat steps (6) and (7) as described above until the thickness of the silicon diaphragm portion 108 reaches the required thickness. (9) As shown in Figure 20, silicon diaphragm part 1
When the thickness of 08 reaches the required thickness, the silicon oxide film 10
3 and the silicon nitride film 104 are removed by etching.

0004

However, in the conventional example shown in FIGS. 14 to 20, etching and thickness measurement of the silicon diaphragm 108 must be repeated many times in order to form the silicon diaphragm 108. Must be. For this reason, (1) the work takes a long time, the etching solution deteriorates,
Reproducibility was poor due to variations in etching speed. (2) Furthermore, since the diaphragm does not have its own protection mechanism against excessive pressure, there is a risk that the diaphragm will be destroyed when excessive pressure is applied.

The present invention solves this problem. An object of the present invention is to provide a method for manufacturing a silicon diaphragm that uses an SOI structure to form a diaphragm with high dimensional accuracy and has an overpressure protection function.

[0006]

[Means for Solving the Problems] In order to achieve this object, the present invention provides a method for manufacturing a silicon diaphragm in which a silicon diaphragm is formed on a silicon single crystal substrate by etching, which is characterized by having the following steps. A method for manufacturing semiconductor devices was adopted. (a) Step of forming a first silicon oxide film on a silicon single crystal substrate. (b) A step of removing the film at required locations by etching, leaving the film in a lattice pattern. (c) A step of selectively epitaxially growing a silicon epitaxial growth layer on the substrate and the surface of the film. (d) forming a second silicon oxide film on the surface of the selective epitaxial growth layer and the surface of the silicon substrate; (e) forming a silicon nitride film on the surface of the second silicon oxide film; (f) A step of patterning the silicon nitride film from the substrate side and etching the substrate to form an etching hole reaching the first silicon oxide film. (g) A step of removing the first silicon oxide film by etching. (h) oxidizing the substrate and the selective epitaxial growth layer through etching holes; (i) forming a sensor element for detecting displacement on the outer surface of the selective epitaxial growth layer facing the oxidized portion of the selective epitaxial growth layer; (j) removing the oxidized portion by etching. (k) A step of removing the silicon nitride film and the second silicon oxide film by etching.

[0007]

[Operation] In the above method, a first silicon oxide film is formed on a silicon single crystal substrate. Required portions are removed by etching, leaving the film in a grid pattern. A silicon epitaxial growth layer is selectively epitaxially grown on the substrate and the surface of the film. A second silicon oxide film is formed on the surface of the selective epitaxial growth layer and the surface of the silicon substrate. A silicon nitride film is formed on the surface of the second silicon oxide film. The silicon nitride film is patterned from the substrate side, and the substrate is etched to provide an etching hole that reaches the first silicon oxide film. The first silicon oxide film is removed by etching. The substrate and selective epitaxial growth layer are oxidized through the etched holes. Oxidize. A sensor element for detecting displacement is formed on the outer surface of the selective epitaxial growth layer facing the oxidized portion of the selective epitaxial growth layer. The oxidized portion is removed by etching. The silicon nitride film and the second silicon oxide film are removed by etching. Hereinafter, a detailed explanation will be given based on examples.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 10 are explanatory drawings for manufacturing essential parts of an embodiment of the present invention. (a) As shown in FIG. 1, a first silicon oxide film 202 is formed on a silicon single crystal substrate 201. (b) As shown in FIG. 2, required portions 203 are removed by etching, leaving the first silicon oxide film 202 in a grid pattern. An example of the lattice shape will be described in detail in FIG. 12. 204 is a resist. (c) As shown in FIG. 3, a silicon epitaxial growth layer 205 is selectively epitaxially grown on the surfaces of the substrate 201 and the film 202. (d) As shown in FIG. 4, selective epitaxial growth layer 20
5 and a second silicon oxide film 206 is formed on the surface of the silicon substrate 201. (e) As shown in FIG. 4, a silicon nitride film 207 is formed on the surface of the second silicon oxide film 206. (f) As shown in FIG. 5, the silicon nitride film 207 is
The substrate 201 is etched by patterning from the 01 side to form an etching hole 208 that reaches the first silicon oxide film. 209 is a resist. (g) As shown in FIG. 6, the first silicon oxide film 202 is removed by etching. (h) As shown in FIG. 7, the substrate 201 and selective epitaxial growth layer 205 are oxidized 21
Do 1. (i) As shown in FIG. 8, selective epitaxial growth layer 20
A sensor element 21 for detecting displacement is provided on the outer surface of the selective epitaxial growth layer 205 facing the oxidized portion 211 of No.
form 2. (j) As shown in FIG. 9, the oxidized portion 211 is removed by etching. (k) As shown in FIG. 10, the silicon nitride film 207 and the second
The silicon oxide film 206 is removed by etching.

As a result, by using the SOI formation technology, the diaphragm etching can be stopped at the oxide film, and the diaphragm thickness can be determined by the thickness of the selective epitaxial growth layer 205. It takes less time and there is no risk of the etching solution deteriorating.
There is no variation in etching speed, and the manufacturing reproducibility is good. (2) Furthermore, as shown in FIG. 11, the silicon substrate 201 can be used as an overpressure protection mechanism against excessive pressure. In addition, as an example of the lattice shape in FIG. 2, FIG.
A pattern A as shown in is possible.

0010

As explained above, the present invention provides a method for manufacturing a silicon diaphragm in which a silicon diaphragm is formed on a silicon single crystal substrate by etching, which comprises the following steps. method was adopted. (a) Step of forming a first silicon oxide film on a silicon single crystal substrate. (b) A step of removing the film at required locations by etching, leaving the film in a lattice pattern. (c) A step of selectively epitaxially growing a silicon epitaxial growth layer on the substrate and the surface of the film. (d) forming a second silicon oxide film on the surface of the selective epitaxial growth layer and the surface of the silicon substrate; (e) forming a silicon nitride film on the surface of the second silicon oxide film; (f) A step of patterning the silicon nitride film from the substrate side and etching the substrate to form an etching hole reaching the first silicon oxide film. (g) A step of removing the first silicon oxide film by etching. (h) oxidizing the substrate and the selective epitaxial growth layer through etching holes; (i) forming a sensor element for detecting displacement on the outer surface of the selective epitaxial growth layer facing the oxidized portion of the selective epitaxial growth layer; (j) removing the oxidized portion by etching. (k) A step of removing the silicon nitride film and the second silicon oxide film by etching.

As a result, by using SOI formation technology, diaphragm etching can be stopped at the oxide film, and the diaphragm thickness can be determined by the thickness of the selective epitaxial growth layer. (1) Working time The etching solution can be shortened, there is no risk of deterioration of the etching solution, there is no variation in etching speed, and the manufacturing reproducibility is good. (2) Furthermore, the silicon substrate can be used as an overpressure protection mechanism against overpressure. Therefore, according to the present invention, by utilizing the SOI structure, it is possible to realize a method of manufacturing a silicon diaphragm in which the thickness of the diaphragm is formed with high dimensional accuracy and also has an overpressure protection function.

[Brief explanation of the drawing]

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

FIG. 2 is a manufacturing explanatory diagram of a main part of an embodiment of the present invention.

FIG. 3 is a manufacturing explanatory diagram of a main part of an embodiment of the present invention.

FIG. 4 is a manufacturing explanatory diagram of a main part of an embodiment of the present invention.

FIG. 5 is a manufacturing explanatory diagram of a main part of an embodiment of the present invention.

FIG. 6 is a manufacturing explanatory diagram of a main part of an embodiment of the present invention.

FIG. 7 is a manufacturing explanatory diagram of a main part of an embodiment of the present invention.

FIG. 8 is a manufacturing explanatory diagram of a main part of an embodiment of the present invention.

FIG. 9 is a manufacturing explanatory diagram of a main part of an embodiment of the present invention.

FIG. 10 is a manufacturing explanatory diagram of a main part of an embodiment of the present invention.

FIG. 11 is an explanatory diagram of the operation of the present invention.

FIG. 12 is a detailed explanatory diagram of main parts of the present invention.

FIG. 13 is a diagram illustrating the configuration of a conventional example that has been commonly used.

FIG. 14 is a manufacturing explanatory diagram of a conventional example that has been commonly used.

FIG. 15 is a manufacturing explanatory diagram of a conventional example that has been commonly used.

FIG. 16 is a manufacturing explanatory diagram of a conventional example that has been commonly used.

FIG. 17 is a manufacturing explanatory diagram of a conventional example that has been commonly used.

FIG. 18 is a manufacturing explanatory diagram of a conventional example that has been commonly used.

FIG. 19 is a manufacturing explanatory diagram of a conventional example that has been commonly used.

FIG. 20 is a manufacturing explanatory diagram of a conventional example that has been commonly used.

[Explanation of symbols]

201...Substrate 202...first silicon oxide film 203...Required locations 204...Resist 205...Epitaxial growth layer 206...Second silicon oxide film 207...Silicon nitride film 208...Etching hole 209...Resist 211...oxidized part 212...sensor element

Claims (1)

[Claims] 1. A method of manufacturing a silicon diaphragm in which a silicon diaphragm is formed on a silicon single crystal substrate by etching, the method comprising the following steps. (a) Step of forming a first silicon oxide film on a silicon single crystal substrate. (b) A step of removing the film at required locations by etching, leaving the film in a lattice pattern. (c) A step of selectively epitaxially growing a silicon epitaxial growth layer on the substrate and the surface of the film. (d) forming a second silicon oxide film on the surface of the selective epitaxial growth layer and the surface of the silicon substrate; (e) forming a silicon nitride film on the surface of the second silicon oxide film; (f) A step of patterning the silicon nitride film from the substrate side and etching the substrate to form an etching hole reaching the first silicon oxide film. (g) A step of removing the first silicon oxide film by etching. (h) oxidizing the substrate and the selective epitaxial growth layer through etching holes; (i) forming a sensor element for detecting displacement on the outer surface of the selective epitaxial growth layer facing the oxidized portion of the selective epitaxial growth layer; (j) removing the oxidized portion by etching. (k) A step of removing the silicon nitride film and the second silicon oxide film by etching.