JPS5983023A - Semiconductor pressure difference detector - Google Patents

Abstract

PURPOSE:To make the relationship between pressure and output linear even at the measuring time for low pressure, by providing regions having different thicknesses in a strain yielding part, and forming strain sensitive elements on the thick strain yielding parts. CONSTITUTION:The diaphragm part of a semiconductor pressure difference detector comprises two stepped parts having different thicknesses, i.e., convex strain yielding parts 34 having a relatively thick size and diaphragm parts 36 having th thickness thinner than the part 34. The end parts of the convex strain yielding parts 34 are connected to a fixing part 30 and form a cross shape. Gage resistors 38 in a P shape are formed on the upper surfaces of the convex strain yielding parts 34 and take out full bridge outputs by pressure. In this constitution, the convex strain yielding parts 34 can yield large strain based on small forces, i.e., low pressures. Therefore, the relationship between the pressure and the output can be made linear even at the measuring time of the low pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a pressure differential pressure detector, and more particularly to a pressure differential pressure detector using a semiconductor itself as a die V-flamm.

[Prior art]

The measurement diaphragm used in the conventional 81 diaphragm type pressure differential pressure detector is made of silicon single crystal and has a thin strain-generating portion and a thick fixing portion surrounding it, and the entire life of the thin strain-generating portion is A plurality of piezoresistive elements are formed on the side using a normal IC process.

The back surface of the peripheral thick portion of this Si diaphragm is bonded to a support made of 7-recon or glass having a thermal expansion coefficient similar to that of silicon and having a vent hole formed in the center.

This 81 diaphragm type pressure differential pressure detector has excellent measurement properties because it can apply IC technology, and since Si single crystal is an ideal elastic material, it has no hysteresis and has excellent p+-m characteristics.

However, a measuring tire flam having such a configuration has a drawback that when an extremely low pressure is to be determined, the surface characteristics of pressure and output are poor. The reason for this is that in order to measure the low-pressure force, it is necessary to reduce the wall thickness at the beginning of the measuring tire flam. This is because young fruits called hiru appear.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor pressure differential pressure sensor that eliminates the drawbacks of the conventional wave jll described above and that does not maintain a linear relationship between pressure and output even when measuring low pressures.

[Summary of the invention]

In order to achieve the above object, in the present invention, regions having different thicknesses are provided in the strain-generating portion, and strain-sensitive elements are formed in nine of the thick strain-generating portions.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail using examples.

FIG. 1 is a cross-sectional view showing the overall configuration of a differential pressure detector, in which there is a measuring diaphragm 10 made of a crystal S1, a hollow first supporting member 12, a hollow second supporting member. 14 to the nozzle 16. The first support member 12 is the measuring diaphragm 1
In consideration of electrical insulation from the 00-no-unong 16 and thermal distortion with the measuring tire flam 10, borosilicate glass, for example, which has a thermal expansion coefficient similar to that of Sl, is used. Further, the second support member 14 has a thermal expansion coefficient similar to 3i.
For example, a Fe--Ni kettle is used.

Here, the measurement tire flamm lO and the first support member 12, and the first support member 12 and the second support member 14 are joined by, for example, an anodic bonding method.

The electrical output from the measuring tire flam 10 is connected to the lead wire 1
8 and how? It is taken out to the outside via a terminal 20 sealed to the ring 16.

Figure 2 is a plan view of the 10 IIS recording short tires viewed from the main surface, that is, the gauge resistance formation side, and Figure 3 is a plan view of the 2
The measurement diaphragm 10 is, for example, an n-type single crystal 3i of (+00)D\I, and is a thin diaphragm part surrounded by a fixed part 30 within the thickness. has. This diaphragm part is formed to have two different thicknesses, and has a relatively thick wall part 34 and a thinner diaphragm part 36, and the strain is...
The cross section 34 has a cross shape with one end connected to the fixed foot section 30.

Four p-type gauge resistors 38 are formed on the upper surface of the strain beam 34 in the direction of the <110> axis, for example, by a diffusion method. It is formed near the fixed end of the beam part 34, two of which are arranged in the radial direction and the other two in the direction perpendicular to the diameter, so that a full bridge output can be obtained by pressure.Measurement diaphragm 100 surface An oxide film that protects the gauge resistor 38 (not shown) and aluminum wiring that outputs the output of the gauge resistor 38 are provided, respectively.

In such a configuration, when a pressure P is applied to the measuring diaphragm 10, the strain beam 34 bends, and at this time, the strain beam 36 of the diaphragm 36 is thinner and softer than the beam 34, so it acts as a mere airtight membrane. Most of the force of the acting and received pressure product SX pressure P acts as a force that deflects the strain force 34. Therefore, the strain Cj: 34 can generate a large strain with a small force, that is, a low pressure.

FIG. 4 shows a second embodiment of the invention. The difference from FIG. 2 is that a wide region with the same thickness as the strain-generating beam 38 is provided at the center of the diaphragm.

In this way, the central portion of the diaphragm becomes relatively stiff, so that the strain generated in the strain beam 34 when pressure is applied is concentrated in the region where the gauge resistor 38 is arranged. Therefore, compared to FIG. 2, it becomes possible to measure even lower pressure areas with good elliptical accuracy.

FIG. 5 shows a third embodiment of the present invention. The difference from Fig. ig2 is that the strain-generating beam 34 has a cantilever shape with one end connected to the fixed part 30. In this configuration, since the strain beam is cantilevered, treetops can be measured even more effectively in a lower pressure range than in FIG. 2.

FIG. 6 shows a fourth embodiment of the invention. The difference from FIG. 2 lies in the separation of the 9 part 34 and the diaphragm part 36 in order to generate strain in the tire flam part, and in that etching from the back surface of the measuring diaphragm 10 is completely adopted. In this shape, both the strain-generating part and the fixed part on the gauge resistance side are flat, and the surface is 810 mm.
2, it has the advantage of increasing the degree of freedom in routing the gold wire on the measurement diaphragm. J: I'm going to growl.

In the embodiments described above, the strain on the tire flam is 9.
This example describes the case where two parts are formed, such as in the shape of a cross, but the number rarer than the strain t may be one,
Of course, it is also possible to use three or more.

〔Effect of the invention〕

As is clear from the above description, according to the semiconductor pressure differential pressure detector according to the present invention, the relationship between pressure and output can be made linear even when measuring low pressure.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the overall configuration of a differential pressure detector to which the present invention is applied, and FIGS. 2 and 3 are configuration diagrams showing an embodiment of the differential pressure detector of the present invention. , Figure 2 is a plan view,
FIG. 3 is a cross-sectional view taken along lines III-II' in FIG. . 10...Measurement tire hum, 30...Fixing part, 32
...Diaphragm part, 34...Original φ is 9 parts, 36...
・Diaphragm part, 38... Gauge resistance. Agent: Patent Attorney Akio Umahashi, Key 9・'・,,,:J,,,. 1st part 2nd part 3rd part 4th part 5th part 5

Claims (1)

[Claims] 1. In a semiconductor pressure differential pressure detector in which a strain sensitive element is formed on the surface of the diaphragm part of a semiconductor substrate having a thick fixing part on the periphery and a thin diaphragm part inside the fixed part, the diaphragm part is strain sensitive. 1. A semiconductor pressure differential pressure detector, characterized in that a beam part is formed in a region where an element is formed to be thicker than in other regions and is connected to the fixed part.