JPS6184537A - Capacitive sensor - Google Patents

Abstract

PURPOSE:To obtain an ideal elastic characteristic by forming a diaphragm on a silicon semiconductor substrate. CONSTITUTION:The 1st n<+> layer 2 and p type epitaxial layer 3 consisting of antimony-diffused layers and a protective film 4 consisting of SiO2, etc. are formed on the substrate 1 constituted of a semiconductor such as p type silicon substrate having elasticity. A protective film 5 consisting of SiO2, etc. is then formed thereon and the 2nd n<+> layer 6 is diffused except the range thereof. The film 5 is removed and the 1st and 2nd n<+> layers are inactivated. The p layer is removed except the n<+> layer. The layer 2 remaining between the etched part of the substrate 1 and the spacing (t) is the diaphragm.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention applies a force corresponding to the pressure generated on the diaphragm to 5
? The present invention relates to a capacitive sensor which uses a semiconductor substrate such as silicon and has a diaphragm formed on the substrate.

<Conventional technology> Measurement pressure is received by a diaphragm (the force generated on the diaphragm is connected to a movable electrode via a connecting rod, and changes in the volume Ω between the fixed molds installed on both sides of the movable mold) are detected. A capacitive sensor having a structure in which two plates facing each other at a certain distance are joined by welding, adhesive, etc. is well known and has already been widely put into practical use. In such a capacitive sensor, (1) welding distortion and thermal expansion coefficient of different material layers if'/
), the device has uniform performance due to distortion etc.
(2) In order to make it compact and highly sensitive, there was a limit to the accuracy of the cap and top.

<Object of the Invention> The present invention has been made in view of the problems of the prior art described above, and therefore, it is an object of the present invention to provide a compact, 8-sensor type sensor with a simple configuration.

The structure of the light of the present invention achieves this purpose with the groove or semiconductor phase of the present invention! 4
A first n(p) layer is diffused onto a p(n) type substrate having a (100) lattice plane, and this first n(p) Ff
A p(n) type epitaxial layer is formed on fi, a protective film is formed in a certain range on this epitaxial layer,
the second n from above the +1(n) type epitaxial layer;
The (p) layer is diffused to such an extent that the p(n) type epitaxial layer remains slightly between it and the first n(p) layer, and after the protective film is removed, etching and underetching are performed. , is characterized in that the ρ (n) type epitaxial layer is removed.

〈Example〉 Figures 1(a) and (b) show an example of a positive displacement type sensor according to the present invention. Figure 1(a) is a plan view, and Figure 1(b) is a first A sectional view taken along line A in FIG. 2(a), and FIGS. 2(a) to 2(C) are process diagrams showing the manufacturing process of the capacitive sensor. In FIG. 2(a), -1 is a board made of an elastic semiconductor. This substrate 1 is, for example, a p-type (impurity moisture content of 10I5 or less) silicon substrate (111 formed convex and convex). C-There is.

Reference numeral 2 denotes a diffusion layer of Sb (antimony) with a non-MA concentration of about 1020, which is diffused on the substrate 1 and forms the first n1N. 3 is a p-type epitaxial layer formed on the first n-layer and has an impurity temperature of about 1015;
1 shows the step of forming the lower periphery of the substrate 1. In this step, as shown in FIG. 1(a), a plurality of protective films 5 such as Sio2 are applied to 81I of a square whose negative side is f.
12 in the figure) are formed in a rhombus shape, and except for this range, the second n''[6 impurity Q degree of about 1020 is diffused.

By controlling the diffusion rate and diffusion time, this second n10 layer 6 can be formed by controlling the diffusion rate and diffusion time to form the first n10 layer 2 which was diffused earlier
The p-type epitaxial layer 3 is stopped just before the p-type epitaxial layer 3
is left with a slight thickness of 1.

FIG. 2(C) shows the etching process.

In this step, the protective film 5 formed on the p-type epitaxial layer 3 is removed, and the substrate 1 is immersed in a 4 to 12 normal KOH solution (about 80°C).
A voltage of about 0.6V is applied between Ff and
Only the first and second n layers are inactivated (passivated), and the p-type layer is removed by etching and under-etching, leaving the n layer (the area indicated by the dotted line in Figure 1(a)). A slight gap t is formed between J5 and the second n+ layer. The first n+ layer 2 remaining between the etched portion of the substrate 1 and the gap becomes a diaphragm, and a sensor is formed between the second n layer 5. When diffusing the second n-layer layer, as shown in Figure 3(a), each vertex Q of the public n*5 square is connected to the vertex Q of the adjacent square with the lattice plane (
It is important to form the film so that it has an overlapping part W in the 11'O) direction; if there is no overlapping part, the apricot etching will proceed as shown in Figure 3 (1)).
L/<R portion bending occurs, and an under-tube portion is not formed as shown by the dotted line in FIG. 1<a>. In addition, this maintenance i1.9 Ill! The shape of 5 is not limited to a square; for example, it can be formed into various shapes such as a rectangle in FIG. 3(c), a circular shape in FIG. 3(d), and an unspecified shape in FIG. Monkey.

If a capacitive sensor with such a configuration is connected to the signal detecting means 10 by forming an electric current (^1. The movement of the first n10 layers that changes depending on the pressure can be detected as a change in capacitance ai.

In this example, the substrate 1 is of p-type, a first n-layer is diffused on this p-type substrate, a p-type epitaxial layer is formed on this, and a first n-layer is formed on this epitaxial layer. However, the substrate 1 is made n-type, the first p-layer is diffused on this n-type substrate, and an n-type epitaxial layer is formed on this, and this epitaxial layer 1! A second p-layer may be diffused over the p-layer. In this case, the first and second
The n-type epitaxy p-/I/F'iJ will be etched, leaving the p-layer. During etching, K O+-
Pt soaked in 1 liquid? The voltage applied to the 12 poles and the 0 layer is +0.
It is necessary to keep it below 5V.

According to the device configured in this way, the diaphragm is formed without welding or applying any other mechanical force, so ideal elastic properties can be achieved and a stable monolithic hinge can be realized. This capacitive sensor can be applied not only as a pressure gauge but also as a microphone LI phone, an accelerometer, a vibration meter, etc.

<Effects of the invention>That's it! As specifically explained with Example i, according to the present invention, it is possible to realize a capacitive sensor that can respond to pressure, output a stable signal, and has a simple configuration.

[Brief explanation of the drawing]

Figures 1 (a) and (b) show a capacitive set substrate according to the present invention, 2... a first n(p) diffusion layer, 3... a p(n)
shaped epitaxial layer, 4, 5... 1 or film, 6...
Second n(p) diffusion layer. /'Ding'Tori'j Agent: Patent Attorney Nobuaki Ozawa,, N\τ--/ Atsushi 1 Figure (a) (b) Atsushi 2 Figure 3 (a) (c) (d) (b) (e)

Claims (1)

[Claims] p(
Diffusion of a first n(p) layer onto an n) type substrate;
A p(n) type epitaxial layer is formed on the n(p) layer, a protective film is formed in a certain range on this epitaxial layer, and a second layer is formed on the p(n) type epitaxial layer. The n(p) layer is diffused to such an extent that the p(n) type epitaxial layer remains slightly between the first n(p) layer, and after the protective film is removed, etching and under-etching are performed. A capacitive sensor characterized in that the p(n) type epitaxial layer is removed by a method.