JPS5826237A - Pressure sensor - Google Patents

Abstract

PURPOSE:To obtain an apparatus obstructing the influence of the distortion stress of the header side with a simple method, by sticking and fitting a silicon pedestal of a pressure sensor chip to a minutely projected part formed in a body on the header surface of a package. CONSTITUTION:A minutely projected part 31a having e.g. about 1-2.5mm.<2> area and 0.2-0.5mm. height, is formed in a body at the central part of a header 31 of a package. Further, a pressure sensor chip 10 is stuck and fitted to said part 31a by e.g. an Au-Si eutectic solder 32. In this manner, the influence of the distortion stress produced at the side of the header 31 exerting on the side of the chip 10 is obstructed sufficiently and orignal characteristic of the chip 10 itself are put to practical use sufficiently, and the accurate measurement of the external pressure is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure sensor that detects pressure using a semiconductor strain gauge, and particularly to a package for mounting and supporting an absolute pressure type pressure sensor.

As is well known, this type of pressure sensor forms a gauge resistor by diffusing impurities into a part of a semiconductor single crystal such as silicon, and measures the change in resistance of the gauge resistor due to pressure strain applied from the outside. and obtain the pressure value.
Functionally, there are two types: absolute pressure type and differential pressure type, and this invention targets absolute pressure type.

Figure 1 shows the cross-sectional structure of this type of pressure sensor chip (lO). That is, this #! In Figure 1, this chip (10) has a silicon diaphragm (12) around which a support part (11) is formed, a silicon pedestal (
13) are bonded together with brazing material (17), and the internal space (14) is made into a vacuum, whereby the diaphragm (12-) is dented by external pressure, and the upper part of this diaphragm (12) is A gauge resistor (15) is formed in a part by an impurity diffusion method, and electrodes (16) for leading out leads are provided on the support part (11).

By the way, in order to package this absolutely positive pressure sensor chip (10), the pressure sensor chip (10) is attached directly to the package head using adhesive or brazing material. The difference in coefficient of thermal expansion between the silicon and the header material imposes a naturally occurring strain on the diaphragm that must be compensated for, and this strain is due to the heating applied during manufacturing. Otherwise, it fluctuates irregularly during the cooling process, etc., and cannot be precisely controlled, which is a major obstacle to mass production.

Conventionally, as shown in FIG. 2, in order to reduce the stress caused by the difference in thermal expansion coefficients as much as possible, the header (21) has an area of, for example, 1 to 2.5 m and a height of 0.0 m.
A micro silicon single crystal support stand of about 2 to 0.5 mm (
22), and the pressure sensor chip (10) and these are adhesively attached using, for example, Au-8i eutectic solder (23), and by the intervention of a minute support stand, the header side This method makes it possible to minimize the strain stress that occurs on the chip side, but on the other hand, this method requires various processing of the brittle silicon single crystal, which is the basic material of the pressure sensor. There was a disadvantage that the processing was very difficult.

In Fig. 2, (24) is a cap with pressure introduction pipe, (25) is an external input/output lead, and (26) is an electrode (16).
) and the lead (25).

In view of these conventional circumstances, the present invention focuses on the fact that the interposition of the silicon single crystal support is synonymous with the protrusion of minute protrusions from the header (21) If, By attaching the pressure sensor chip(s) with adhesive, the same purpose can be achieved without processing the support base.

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIG.

In this example shown in Fig. @3, the same reference numerals as in the conventional example shown in Fig. @2 indicate the same or corresponding parts. , similarly the area is 1 to 2.5 m7F1',
Microscopic protrusions with a height of about 0.2 to 0.5 mm (31 m)
is integrally protruded, and the Au
-81 eutectic solder (23) etc. to the pressure sensor chip (
10) is attached with adhesive.

Therefore, even in this embodiment configuration, the above #! As in the case of the conventional example shown in FIG. 2, it is possible to sufficiently prevent the strain stress generated on the header (31) side from affecting the chip (10) side.

As detailed above, according to the present invention, instead of the conventional silicon single crystal support, a minute convex portion is integrally protruded from the header, and a pressure sensor chip is adhesively mounted on the minute convex portion. Therefore, there is no need to process a separate support base, the formation of the small convex part on the forehead is easy as it is integrated with the header, and the adhesive installation can be done in the same way as before, reducing distortion on the header side. It is possible to prevent stress from reaching the sensor side as much as possible, to fully utilize the inherent characteristics of the pressure sensor chip itself, and to accurately measure external pressure.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the general structure of an absolute pressure sensor chip, FIG. 2 is a cross-sectional view showing a package of a conventional absolute pressure sensor chip, and FIG. 3 is the same as the same to which an embodiment of the present invention is applied. It is a sectional view showing a package. (lO)...pressure case/sachig, (12)...
Silicon diaphragm, (13)...Silicon pedestal, (15)...e...Gauge resistor, (16)φ...Electric i,'(31)...Header, (31m)...
Microscopic protrusions. Agent S Shu Xin - (1 other person)

Claims (1)

[Claims] A silicon diaphragm forming a gauge resistor. and a pressure sensor chip consisting of a silicon pedestal,
A pressure sensor characterized in that a minute convex portion is integrally formed on the header surface, and a silicon pedestal of the pressure sensor chip is adhesively attached onto the minute convex portion.