JPS59125666A - Semiconductor pressure sensor and manufacture thereof - Google Patents

Abstract

PURPOSE:To form a diaphragm of a semiconductor pressure sensor having good reproducibility by empolying the combination of silicon epitaxial growth technique and anodic growth technique. CONSTITUTION:An N type buried layer 5 is selectively arranged on a P type silicon substrate 1, and an N type epitaxial layer 6 is formed. Then, a P type isolating layer 7 formed to reach the substrate 1 from the main surface of the layer 6 to surround a position to become a thin plate part of a diaphragm later. Subsequently, a resistor 8 as a strain gauge and a base 8' of an N-P-N type transistor capable of being simultaneously formed are formed by boron ion implanting or diffusing, and further the emitter 9 of an N-P-N type transistor and the collector 9' of an N-P-N type transistor capable of being simultaneously formed are formed by arsenic or phosphorus ion implanting or diffusing. Thereafter, an insulating film 10 such as an SiO2 or Si3N4 film to become a mask of anodic reaction is arranged, an anodic reaction is performed, the substrate 1 is formed in porous state from the back surface scale, and the porous region 11 is partitioned by the layer 6. Then, the entire main surface of the layer 6 is covered with antioxidative insulating film such as Si3N4 film, the entire region 11 is oxidized in steam atmosphere or the like, and the oxidized film is then removed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor pressure sensor, and in particular to a simple structure and manufacturing method of a silicon diaphragm.

The half 4-body pressure sensor is made entirely of a Tsujisamu Noricon diaphragm, and a half 5N piezoresistive strain gauge is built on its surface by diffusion. This method takes advantage of the fact that when the tire diaphragm receives pressure, the thin plate of the diaphragm is distorted, and the resistance, which is a strain gauge, fluctuates due to the piezoresistance effect.

This type of semiconductor pressure sensor r medical use 1 For example, when applied to various internal body pressures or plate pressure measurements, the detection signal is very weak, so the diaphragm plate is used as a pressure sensor. The σ of the thin part needs to be 10 to 60 μm, and the degree of graininess is also required to be strict.

To form the temporary thin Btlk of the above diaphragm, conventionally, it is masked along the Ayu crystal plane orientation (10 (all 11 planes + 110) direction) of silicon and anisotropically made with a potassium hydroxide-based or ethylene-amine-based alkaline solution. This flI will be simply explained with reference to FIG. Figure 1 (!1) is a silicon rib surface view before all rows 9 of anisotropic etching, with an n-type silicon group 4? i i l/
A p-type strain gauge 2 is formed, and the entire surface 6
1 Io2 or S i3 N4, etc., the film 6 is formed, and the back side of the n-type silicon substrate 1 is left with an opening for silicon etching, and the surface and the included Zetsutai film 4 are selectively etched. is formed. FIG. 1(b) shows a cross-sectional view of silicon after etching at high temperature using the aforementioned etching solution, such as potassium hydroxide, isopropyl alcohol, ethyl alcohol, or aqueous solution. In this way, the diaphragm waiting for the tapered silicon I-temporary support Yq section (Fig. 1 (1))
There is no way it can be formed, but this semi-solid pressure sensor is waiting for the next IX battle.

(1) The Ml composition of the etching solution, the etching atmosphere, and the etching salt # must be 1v1.

(2+ (Even after carrying out the arrangement of 11, it is necessary to pop the etching hole several times during etching, and check the entire etching progress 61).

(3) Due to defects in the silicon base circle or reoccurrence of residual metal, 44 lines may not be partially etched (b).

(Potassium hydroxide in the 4-inch etching solution is a semi-reliable supernatant, and when using it, all stages of the F14 equipment must be fully cleaned.

The object of the present invention is to provide a method and structure for folding and folding a semi-heavy pressure capacitor without the above-mentioned points and at low cost. A combination of Shall J gray technology and anodization member technology? By using Furukawa's good half-barrel pressure sensor, a full-length flammable die A' is used.

The following drawings ζ will therefore be used to illustrate the present invention.

FIG. 2(a) is a diagram in which an n-type epitaxial layer rQi 6 is selectively formed on a p-type silicon substrate 1 with a 1q-type buried layer 5 all over. Here, the buried layer 5 acts as a buried collector of the IIPN transistor when the temperature compensation circuit, amplifier circuit, and 1g modulation circuit are all formed monolithically with the strain gauge, and is not necessarily necessary. In the figure shown above, the entire thin plate part of the diaphragm will be formed later in the middle of the buried layer 5 (11). However, if the thickness of the thin plate is about 10 μm, it is preferable not to place it on the keyaki of this example. : This can be done by water cumulative decomposition of silicon chloride such as SiO!-4, but in this case the total thickness can be kept within ±2%.Furthermore, even better control is possible by using the thermal decomposition sound of SiH4. .

Figures (b) and (f) show the complete formation of the P-type separation layer 7, which was formed so as to reach the P-type silicon substrate 1 from the surface of the n-type epitaxial) @6 so as to surround the area that would later become the temporary thinned part of the diaphragm. This is a diagram L. The P-type dividing layer can be formed by ordinary boron diffusion, but it is preferable to have a shape that completely surrounds the entire thin part of the diaphragm.

Figure 12 (C) shows a resistor 8 which is a strain gauge, and a base 8' of an NPNI transistor which can be formed at the same time.
Emitter 9 of the transistor and NP that can be formed at the same time
This is a diagram showing an N transistor formed by ion implantation of phosphorus, or by ion implantation.

Figure 2 ((1) shows the 8i02°s mask for anodization.
i3 N4 'fr, which diaphragm membrane 10 is arranged (7) In the figure, the hole 10 is smaller than the inner circumference of the P-type dynamic layer 7 and the opening 11 is closer to the P-type dynamic layer than the resistor 8. Determined based on the results.

Figure 2 (e) shows a %P-type silicon substrate 1 after anodization.
is j long side i11! This is a diagram showing that the porous subterranean region 11 is exposed in the layer 6 of the 7th layer. Hiroshi Hiroshi of Disaster Management of Anodization/! This will be explained using the schematic diagram of anode formation shown in Fig. 6. rib-31%i is a P-type dynamical layer 7, P-type silicon-tIy: tentative 19 reaction number 1
2. The anode IL formation reaction system is related to 44 τ from the ghost electrode 13° The reaction progresses as holes are injected from the P-type movable layer 7 into the P-type silicon substrate 1 by the thermal conductor 14 and flow toward the opening portion of the insulating film 100.

Part 1. As the anode IL formation reaction progresses, the P-type silicon substrate 1 becomes more porous starting from the openings in the insulating film 1o. When the thickness of the P-type silicon substrate 1 is 500 μm, the P-type silicon substrate 1 becomes porous in a reaction time of 35 minutes using a 50% hydrofluoric acid aqueous solution and a chemical formation flow rate of about 400 Δ / kidney.
It reaches the boundary of the n-type epitaxial layer B. Since the n-type epitaxial IfI6 is not injected with ζ based on the chemical formation current, the n-type epitaxial layer 6 is not porous or porosity (c). Since the chemical 1jX advances in the Q direction, the insulating film 1
When viewed from the square 0, it is approximately quarter circle shaped.

No. 21'J(f) is after coating the entire main surface of the n-type Ebitaki 7 layer with an oxidation-resistant insulating film such as 5L3N4, and then covering the entire area 11 in the front => porous area in a water vapor atmosphere. FIG. 3 is a diagram showing the entire cross-sectional structure of the final silicon portion after intensive oxidation and subsequent complete removal of the l'Iq film. Since the oxidation of the pores 17 proceeds selectively compared to the single crystal part, the thickness of the thin plate part of the tire flam should be determined carefully with the thickness of the epitaxial layer B.

In the above example, 1w polar formation, 1w 1hi? all half 4
Although the body region is formed by force, the invention is not limited to this, for example (/i'2'lJ Perform Ihi, '1
- 1 barley anodic chemical oxidation V in which a semiconductor region of BeC is formed
It is also a step to remove all the Pr.

From the description of the above embodiments, it can be seen that in the pressure sensor of the present invention, the false thin portion of the diaphragm is P,! It can be seen that the inner surface of the silicon substrate supporting the entire thin plate area surrounded by the 4' m area has the shape of a quarter circle.

According to the above invention, due to the selective oxidation of P and n-type silicon, the batch process of half-pressure Kasensa Taizo becomes 01it:, which is 11j1 compared to the conventional half-pressure Zoqryu process.
There is no need to use any chemicals that are harmful to the body, and l
In addition to the gauge part of the semiconductor pressure sensor, there is also a full sleeve inspection! 2
It is easy to integrate the 1-way, 9-increase, 1-input modulation circuit, and the 1-digit modulation circuit.

[Brief explanation of the drawing]

211 (a) and (b) fully explain the manufacturing method of the 4-year-old pressure sensor, and Figures 2 (a) to (f) show the direct manufacturing method of the uninvented semiconductor sensor. Cross-sectional view of process order. Fig. 5 (schematic diagram for explaining l factory +, y fe, hi. 1... P-type silicon base θ2.8 pu... strain gauge resistance 4.10..., insulating film 6... N-type epitaxial layer 7... P-type separation layer 11.
... Porous region 12 ... Reaction slag
13...Chemical cathode 14...Casei Power Supply and above Applicant: Sunikou Kosha Co., Ltd. Patent Attorney Mogami 6 Figure 2 (d)

Claims (2)

[Claims] (1) In a silicon pressure sensor vC in which the pressure receiving part is a diaphragm, the periphery of the pressure receiving part is surrounded by a P conductivity type region on a plane, and the inner cross section of the silicon substrate support part from which the entire pressure receiving part can be seen? A half-quadruple body pressure sensor characterized by being formed into a quarter-circle shape. (2) N-type silicon on a P-type silicon substrate? A step of epitaxial vapor phase growth, a step of selectively forming a P-type isolation layer from the main surface of the n-type silicon to the P-type silicon substrate, and a step of selectively forming a P-type isolation layer on the back surface of the P-type silicon by itself.・The process of forming a diaphragm, and separating the P-type from the front tube (t=all one electrode), inserting a hydrofluoric acid solution between the other metal electrode and the P-type silicon, and selectively anodizing all the P-type silicon. A manufacturing method of a half-four non-pressure sensor consisting of a process and a process for oxidizing and then removing the P-type silicon region that has been anodized.