JPH01302773A - Semiconductor tension sensor - Google Patents

Abstract

PURPOSE:To form a highly precise diaphragm part, and increase breakdown voltage by forming a first single crystal semiconductor layer on an etching stopper layer, followed by forming thereon, an intermediate insulating layer, and a second single crystal semiconductor layer on the insulating layer and a first single crystal semiconductor layer. CONSTITUTION:On a semiconductor substrate 11, an etching stopper layer 12 composed of an insulating layer formed on a diaphragm region. A first single crystal semiconductor layer 13 is formed on both the substrate 11 and the stopper layer 12. An intermediate insulating layer 16 is formed in the diaphragm region on the semiconductor layer 13. A second single crystal semiconductor layer 15 is formed on both the insulating layer 16 and the semiconductor 13. A piezo resistor 18 is formed in the surface of the semiconductor layer 15. The substrate 11 is etched from the lower part to the central part, and a recessed part 19 with a depth reaching the stopper layer 12 is formed. The upper part is formed in the diaphragm part 20. Thereby, the diaphragm part 20 is formed with high precision, and breakdown voltage is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor pressure sensor in which a piezoresistor is formed on the upper part of a semiconductor substrate, and particularly relates to an improvement in which the diaphragm portion is thickened.

[Conventional technology]

FIG. 4 is a front view of a conventional semiconductor pressure sensor disclosed in, for example, Japanese Unexamined Patent Publication No. 62-288679. In the figure, reference numeral 1 denotes a semiconductor substrate made of single-crystal silicon, and an etching stopper layer (hereinafter referred to as Fr-stone layer J) 2 made of an insulating layer (810J2) is formed on the surface of the semiconductor substrate 1.

It is formed in the diaphragm region by photo-etching. 3 is a single crystal silicon layer formed on the substrate l and stopper R2 by an epitaxial method and recrystallized, and 4 is an insulating layer (Si) formed on this silicon WJ3 soil.
n@), a diffusion window 4a is formed. 5 is board 1
An insulating layer (810 m) formed on the bottom surface, 6 is a resistor formed by implanting boron into the silicon layer 3, and 7 is a resistor formed in the substrate 1 by etching from a central hole etched in the insulating layer 5. , stopper J7J 2
It is a recessed part which has reached a depth of 100 cm, and a thin diaphragm part 8 is formed at the upper part.

In this way, the diaphragm portion 8 is made to have a precise thickness.

[Problem to be solved by the invention]

In the conventional semiconductor pressure sensor as described above, the semiconductor layer 3 of the stopper layer 2 cannot be made very thick because polycrystalline silicon is subjected to a single crystallization process.

For example, it is thin, with a thickness of about 0.5 μm, and has a problem in that it cannot have a high breakdown voltage.

The present invention has been made to solve these problems, and an object thereof is to obtain a semiconductor pressure sensor in which a diaphragm portion is formed to a required thickness with high precision and has a high breakdown voltage.

[Means to solve the problem]

In the semiconductor pressure sensor according to the present invention, an etching stopper layer made of an insulating layer is formed on a semiconductor substrate in a diaphragm region, a first single crystal semiconductor layer is formed on the stopper layer and the substrate, and the semiconductor layer An intermediate insulating layer is formed on the intermediate insulating layer, and a second semiconductor layer is formed on the intermediate insulating layer and the first semiconductor layer.
A single crystalline conductor layer is formed, a piezoresistor is formed in the surface of this second semiconductor layer or on an upper insulating layer formed on this second semiconductor layer, and the substrate is etched from the bottom surface to the center part. A recessed portion reaching the stopper layer is formed, and the upper portion is a diaphragm portion having a required thickness.

[Effect]

In this invention, a first single crystal semiconductor layer is formed on an etching stopper layer, and an intermediate insulating layer is roughly formed on the first semiconductor layer in order to compensate for the thinness of this semiconductor layer and achieve a desired thickness. However, since a second single crystal semiconductor layer is formed on this insulating layer and on the first semiconductor layer, the diaphragm portion can be formed to a desired thickness with high precision, and the breakdown voltage can be increased.

〔Example〕

FIG. 1 is a top view of one embodiment of a semiconductor pressure sensor according to the present invention. 11 is a semiconductor substrate made of single-crystal silicon; 12 is an etching stopper layer (hereinafter referred to as "stopper layer") made of an insulating layer (such as 810S) formed on the substrate 11 in the diaphragm region;
Reference numeral 13 denotes a stopper layer and a first single crystal silicon layer formed on the substrate l.

Due to single crystallization, the thickness is, for example, 0.5 μm. 1
4 is an intermediate insulating layer (such as 810s) formed on the silicon layer in the diaphragm region, and b is a second single crystal silicon layer formed on this intermediate insulating layer and on the first silicon layer 13. is an upper insulating layer (810s, etc.) formed on this second silicon layer 15, in which a diffusion window 16& is opened. 17 is 'F formed on the F side of the substrate U.
An opening 17a corresponding to the diaphragm region is formed in the center of the insulating layer (810).

18 is a piezoresistance formed by diffusion in the surface of the second silicon layer; 19 is a recess formed in the substrate 11 by etching from below to a depth reaching the stopper layer ν; The diaphragm part is added. Note that electrode wiring connecting each piezoresistor and a protective film covering the upper part are provided, but illustration thereof is omitted.

Next, the manufacture of the above pressure sensor will be explained with reference to FIG. First, as shown in FIG. 2 (IL), an insulating layer (for example, 810-) is formed on the entire upper surface of the semiconductor substrate 11 made of single crystal silicon, and then the diaphragm region is left and the rest is removed, as shown by the solid line. Forming a stopper layer.

Subsequently, as shown in FIG. 2(b), a polycrystalline silicon layer is formed on the stopper layer and the substrate 11 by an epitaxial method or the like, and this is formed into a first single crystal silicon layer B by laser annealing or the like. do.

As shown in FIG. 2(o), an insulating layer M is formed on the first silicon layer B.
(for example, 810 m 2 ) is formed over the entire surface, and then the diaphragm region is left and the rest is removed to form the intermediate insulating layer 14 shown by the solid line.

26th (As in (1), a polycrystalline silicon layer is formed on the intermediate insulating layer 14 and the first silicon layer m by an epitaxial method, etc., and this is laser annealed to form a second single crystal silicon layer. Make it correct.

Next, as shown in FIG. 2(e), an upper insulating layer (for example, 810 m) 16 and a lower insulating layer (for example, 810 m) 17 are formed on the upper surface and downward, and then the diffusion window 16 and the opening are formed by etching. Open the part 17a.

'Pj2 As shown in FIG. 2(r), a piezoresistor is formed in the surface of the second silicon layer 15 by diffusion or the like.

Furthermore, as shown in the first step d, the substrate 11 is etched from below to form a recessed portion with a depth that reaches the stopper layer 12iC.

Next, electrode wiring for connecting each piezoresistor and extending it to the outside is formed by a known method (not shown).

In this way, the first silicon layer 13, the intermediate insulating layer 14, and the second silicon layer 15 are stacked on the stoppers fil 1 and 2, and are formed to have an accurate thickness.
By forming the recessed part 9 in the upper part of the diaphragm part 1, the upper part can be made into a diaphragm part having the required thickness.

No. 8N shows another embodiment of the semiconductor pressure sensor of the present invention. I'm really into it. A stopper layer is formed on the semiconductor substrate 11 and a first silicon layer 13 is formed.
#14% second silicon layer 15 in the middle on top? form,
The structure in which the F section insulating layer 17 is formed and the recess 19 is formed is the same as that shown in FIG. 1 above.

However, the following methods are different.

n is an upper insulating layer (for example If 5ins) formed on the second silicon layer 15 in the diaphragm region, and ρ is an upper insulating layer formed on this insulating layer by an epitaxial method or the like to form single crystal silicon, and then etched. It is a piezo resistance.

(Effects of the Invention) As described above, according to the present invention, an etching stopper layer made of an insulating layer is formed on a semiconductor substrate, a first single crystal semiconductor layer is formed on this and on the substrate, and the etching stopper layer is formed on the semiconductor substrate. forming an intermediate insulating layer thereon; forming a second single crystal semiconductor layer on the insulating layer and the first semiconductor layer; and forming an intermediate insulating layer on the second semiconductor layer or the semiconductor layer; A piezoresistor is formed on the upper insulating layer, and the center E'tl is formed from the bottom of the substrate.
S k is etched to form a recess that reaches the stopper layer, and the upper part is the diaphragm part, so the diaphragm part can be made to the required thickness with high accuracy, the breakdown pressure can be made cylindrical, and the measurement pressure range can be expanded. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of a semiconductor pressure sensor according to the present invention, FIG. 2 is an explanatory diagram showing the manufacturing method of the pressure sensor of FIG. 4 is a sectional view of a conventional semiconductor pressure sensor. In M, 11 is a semiconductor substrate, 12 is an etching stopper layer, and 13 is a first single crystal semiconductor layer (single crystal semiconductor layer). crystalline silicon layer),
14 is an intermediate insulating layer, 15 is a second single-crystal semiconductor layer (single-crystal silicon layer), the slide is a piezoresistor, 19 is a recessed portion, the head is a diaphragm portion, and 21 is an upper insulating layer. n is a piezoresistance. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] A semiconductor substrate having an etching stopper layer formed on the upper surface thereof in a diaphragm region, a first single crystal semiconductor layer formed on this substrate and the etching stopper layer, and a first single crystal semiconductor layer having a diaphragm region formed on the semiconductor layer. a second single crystal semiconductor layer formed on the insulating layer and the first semiconductor layer; a diaphragm region within the surface of the second semiconductor layer or on the second semiconductor layer; A piezoresistor is formed on the upper insulating layer formed on the substrate, and the center portion of the substrate is etched from below to form a recessed portion deep enough to reach the etching stopper layer, and the upper portion is a diaphragm portion. Features of semiconductor pressure sensor.