JPH0158672B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor pressure detection device.

A conventional device of this type is shown in FIG. In the figure, 1 is an N-type semiconductor substrate formed with a thinner central portion, 2 is a plurality of P-type strain meter elements arranged on the surface of the N-type semiconductor substrate 1, and 3
5 is an electrode for connecting the P-type strain gauge element 2 and the wire 4, 5 is an insulating film such as SiO ₂ or Si 3 N 4 that protects the surface of the N-type semiconductor substrate 1 and the P-type strain gauge element 2, and 6 is an electrode for connecting the P-type strain gauge element ₂ and the wire ₄ . N
adhesive for bonding the shaped semiconductor substrate 1 to the support base 7;
is a terminal provided on the support base 7 and to which the wire 4 is connected, and 9 is a protective resin film that covers the wire 4 and the terminal 8, and is made of, for example, acrylic resin, fluorine resin, epoxy resin, polyimide coated by electrophoresis. , melamine resin, xylene resin, silicone resin, fluorine, rubber, etc.

This device detects the applied pressure by measuring the amount of change in the electrical resistance of the P-type strain gauge element 2 via the terminal 8 when the N-type semiconductor substrate 1 is distorted according to the applied pressure. can do. At this time, when the area around the electrodes 3, wires 4, and terminals 8 is filled with conductive material, leakage current causes variations in electrical resistance characteristics. In order to prevent this, the surfaces of the electrodes 3, wires 4, and terminals 8 and the end surfaces of the N-type semiconductor substrate 1 are covered with a resin film 9.

However, it is extremely difficult to eliminate all pinholes on the end face of the N-type semiconductor substrate 1, which has a large area. A leakage current flows between the N-type semiconductor substrate 1 and the N-type semiconductor substrate 1, resulting in characteristic fluctuations, resulting in low reliability against contamination.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and the semiconductor layer in which the strain meter element is formed is supported on a support stand via a semiconductor substrate of a different conductivity type, and this semiconductor layer is The pressure sensing element is surrounded by an annular diffusion layer of the same conductivity type to completely isolate it electrically, and the electrodes, wires, and terminals of the strain gauge element are covered with an insulating resin film made by electrophoresis. Eliminates the need for a resin film covering the side surfaces, and also eliminates the need for electrodes 3, wires 4, and terminals 8.
This prevents leakage even if a single pinhole is formed in the resin film covering the tube.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, 10 is a P-type semiconductor substrate formed thin in the center, 1a is an N-type semiconductor layer provided on the substrate 10, and 11 is an N-type semiconductor layer 1a.
This is a P-type semiconductor diffusion layer formed to surround the strain meter element 2 and reach the P-type semiconductor substrate 10. Further, 9 is an insulating resin film formed by electrophoresis, and is coated only on the electrically exposed and conductive parts of the electrodes 3, wires 4, and terminals 8.

In the device configured in this way, the N-type semiconductor layer 1
The region a where the P-type strain gauge element 2 is formed is formed by a PN junction made up of the P-type strain gauge element 2 and the N-type semiconductor layer 1a, and an NP junction made up of the N-type semiconductor layer 1a and the P-type semiconductor substrate 10. Completely electrically isolated. Therefore, when the area around the electrodes 3, wires 4, and terminals 8 is filled with conductive substances, two parts of the resin film 9 covering these conductive parts, which have different potentials, are simultaneously exposed to the electrodes 3, wires 4, and terminals 8. If the above pinholes do not occur, no leakage current will flow. However, if the probability that one pinhole will occur in the resin film 9 is P, the probability that two pinholes will occur is expressed as ^P2 , and the probability of occurrence is very small, resulting in less contamination compared to conventional equipment. This makes it a highly reliable detection device.

In the above embodiment, the entire back surface of the N-type semiconductor layer 1a provided with the P-type strain meter element 2 was in contact with the P-type semiconductor substrate 10, but as shown in FIG.
It is composed of a type semiconductor thin plate 1b, the back surface of which is covered with an insulating film 5.
It may also be a structure covered with.

Furthermore, although the above embodiments have all shown cases where a P-type semiconductor substrate 10 is used, an N-type semiconductor substrate may also be used. In this case, the same effect can be obtained by reversing the PN of each semiconductor layer. .

The present invention includes a strain gauge element formed on a surface of a semiconductor layer forming a diaphragm, in which the semiconductor layer is formed on a semiconductor substrate of a different conductivity type, and the strain gauge element is formed on a semiconductor substrate having a different conductivity type. an annular diffusion layer of the same electric type as that of the substrate, which surrounds the surface area of the semiconductor substrate and reaches the semiconductor substrate; and an insulating resin film formed by an electrophoresis method that covers the electrodes, wires, and terminals of the strain meter element. Since the semiconductor layer on which the strain gauge element 2 is formed is completely electrically isolated and the electrodes 3, wires 4, and terminals 5 are covered with a resin film, a highly reliable semiconductor pressure detection device against contamination can be obtained. There are benefits to be gained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional side view showing a conventional semiconductor pressure detection device, FIG. 2 is a cross-sectional side view of one embodiment of the present invention, and FIG. 3 is a cross-sectional side view of another embodiment of the present invention. In the figure, 1 is an N-type semiconductor substrate, 1a is an N-type semiconductor layer, 1b is an N-type semiconductor thin plate, 2 is a strain meter element, 3 is an electrode, 4 is a wire, 5 is an insulating film, 7 is a support base, and 8 is a A terminal, 9 a resin film, 10 a P-type semiconductor substrate, and 11 a P-type semiconductor diffusion layer. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A semiconductor pressure sensing device including a strain gauge element formed on the surface of a semiconductor layer forming a diaphragm, on which the semiconductor layer is formed and which has a conductivity type different from that of the semiconductor layer. a semiconductor substrate, an annular diffusion layer of the same conductivity type as the substrate surrounding the area where the strain meter element is formed and reaching the semiconductor substrate, and covering the electrodes, wires, and terminals of the strain meter element. 1. A semiconductor pressure detection device comprising: an insulating resin film formed by electrophoresis. 2. Semiconductor pressure detection according to claim 1, wherein a portion of the semiconductor substrate forming the diaphragm is removed by etching, and the semiconductor layer in the portion is covered with an insulating film. Device.