RU165465U1 - SEMICONDUCTOR PRESSURE SENSOR - Google Patents

Abstract

A semiconductor pressure sensor, consisting of a single-crystal silicon thin n-type diaphragm in a silicon frame, a strain gauge formed in the diaphragm near the border with the frame in the form of a system of p-type rectangles, four conductors of heavily doped p-type silicon conductive in contact with rectangles of the strain gauge device on the one hand and with metallized wiring on a silicon frame on the other hand, characterized in that the strain gauge The structure of the rectangles is made in the form of a square frame oriented along the directions of the [110] family, and the conductors at the points of contact to the corners of the square frame are made in the form of identical rectangles with sides parallel to the sides of the square frame and completely overlap the corners of the square frame of the strain gage with gaps between sides of the conductors and sides of the angle of the square frame of at least 1 alignment errors.

Description

The scope of the proposed utility model is the field of microelectronics, engaged in the development and manufacture of pressure sensors used, for example, in electronic altimeters.

A semiconductor pressure sensor is known, consisting of a single-crystal silicon thin diaphragm of n-type conductivity in a silicon frame, a strain gauge device in the form of resistors, each of which is formed along four axes of the diaphragm at the border with the frame, four conductors of heavily doped silicon p-type conductivity in contact with resistors of the strain gauge device on the one hand and with metallized wiring on a silicon frame on the other hand (see, for example, the article “Integrated silicon pressure generator with trimming resistors on a crystal "V.I. Vaganov, V.V. Beklemishev, N.I. Gocharova, A.B. Noskin in the journal" Measuring equipment ", No. 5, pp. 28-30, 1980, the book "Integral strain transducers" V.I. Vaganov, 1983, pp. 110-111).

The main disadvantage of this sensor is that it requires complex temperature compensation circuits, since the elements of the strain gauge device are spaced around the perimeter of the diaphragm and can be heated unequally by the electronic elements of the stabilizer, amplifier, and temperature compensation circuitry, each of the elements of the strain gauge device separate adjustment.

Closest to the proposed one is a semiconductor pressure sensor, consisting of a single-crystal silicon thin n-type diaphragm in a silicon frame, a strain gauge formed in the diaphragm near the border with a frame in the form of a system of p-type rectangles of x-shaped conductivity, the axes of which are oriented in direction [100], four conductors of heavily doped p-type silicon conductivity in contact with the rectangles of the strain gauge device on the one hand and meta lined wiring on a silicon frame on the other hand (see, for example, US patent US 4317126, class H01L 29/84 of February 23, 1982).

This semiconductor pressure sensor is a silicon diaphragm onto which an x-shaped tensometric structure is formed by ion implantation, formed by a wide rectangle and a narrow p-type rectangle passing through its middle. The wide rectangle is oriented along the crystallographic direction [100] and forms an angle of 45 ° with the edge of the diaphragm, a current is set through it. A narrow rectangle is used to detect and measure the transverse stress generated in response to the bending of the diaphragm. The width of the current rectangle must be larger in order to increase the potential difference between the edges of the rectangle.

Thus, the x-shaped tensometric structure develops an output voltage that is directly proportional to the applied pressure. In turn, the location of all the elements of the x-shaped tensometric structure at one boundary of the diaphragm eliminates their uneven heating. This sensor has high linearity, repeatability, reproducibility and signal-to-noise ratios.

The disadvantage of this sensor is that the side of the wide rectangle of the x-shaped tensometric structure closest to the diaphragm boundary is shunted by its opposite side remote from the diaphragm. In addition, such a design requires perfectly accurate combination of the elements of the strain gauge device and the conductors, since the slightest displacement will cause a mismatch.

The result of the proposed utility model is to increase the sensitivity and minimize the influence of the accuracy of the combination of conductors and elements of the strain gauge device.

This result is achieved by the fact that in the proposed semiconductor pressure sensor, consisting of a single-crystal silicon thin n-type diaphragm in a silicon frame, a strain gauge device formed in the diaphragm near the border with a frame in the form of a system of p-type rectangles of conductivity, four conductors of heavily doped silicon p-type conductivity in contact with the rectangles of the strain gauge device on one side and with a metallized wiring on a silicon frame with On the other hand, the strain gauge device made of rectangles is made in the form of a square frame oriented along the directions of the [110] family, and the conductors at the points of contact to the corners of the square frame are made in the form of identical rectangles with sides parallel to the sides of the square frame and completely overlap the corners of the square frame of the tensometric devices with gaps between the sides of the conductors and the sides of the angle of the square frame of at least 1 alignment error.

This design eliminates the need for shunting between the side of the strain gage device closest to the diaphragm boundary and its opposite side, remote from the diaphragm, due to the presence of an undoped square portion inside the square frame of the strain gage. Thus, the sensitivity of the sensor is increased. Conductors made in the form of identical rectangles with sides parallel to the sides of the square frame at the points of contact to the corners of the square frame allow you to maintain the active length of the rectangular sides of the square frame of the strain gauge device even with inaccurate alignment of the conductors and elements of the strain gauge device.

The essence of the proposed utility model is illustrated by figures. The design of the proposed semiconductor pressure sensor is shown in FIG. 1 (top view), FIG. 2 (enlarged fragment) and FIG. 3 (section).

With reference to FIG. 1-3 are indicated:

1 - silicon thin diaphragm;

2 - silicon frame n-type conductivity;

3 - strain gauge device in the form of a system of p-type rectangles of conductivity;

4 - conductors of heavily doped silicon p-type conductivity;

5 - a layer of silicon oxide;

and - the gap between the sides of the conductors and the sides of the angle of the square frame of the strain gauge device, equal to at least 1 alignment errors.

The manufacturing procedure and design of a semiconductor pressure sensor with a diaphragm of 1 × 1 mm are described below. The gap between the diaphragm boundary and the 10 µm strain gauge. The width of the sides of the square frame of the strain gauge device is 10 μm.

The proposed semiconductor pressure sensor can be made as follows: on a silicon single crystal plate with a diameter of 100 mm of orientation (100) of the KEF-4 brand, a layer of thermal silicon oxide, 0.6 μm thick, is grown and holes are etched under the active regions; on the front side of the silicon wafer by diffusion of boron, conductors of p + type conductivity 4 are formed with a depth of 2 μm and a surface resistance of 15 Ω / square (see Fig. 1); then, using photolithography, a square frame of a p-type conductivity strain gauge device 3 with a depth of 1.2 μm and a surface resistance of 250 Ω / square is formed by ion doping of boron; then build up a layer of silicon oxide 5 (see Fig. 3), obtained in plasma under reduced pressure, a thickness of 0.6 μm, and etched holes for contact windows to metallization; then, by magnetron sputtering, a layer of aluminum with a thickness of 1 μm is applied, a metallized wiring is formed by photolithography; Further, a thin diaphragm 1, for example, 10 μm thick and 1 × 1 mm in size, is formed on the reverse side of the wafer by anisotropic liquid chemical etching of silicon.

Claims (1)

A semiconductor pressure sensor, consisting of a single-crystal silicon thin n-type diaphragm in a silicon frame, a strain gauge formed in the diaphragm near the border with the frame in the form of a system of p-type rectangles, four conductors of heavily doped p-type silicon conductive in contact with rectangles of the strain gauge device on the one hand and with metallized wiring on a silicon frame on the other hand, characterized in that the strain gauge The structure of the rectangles is made in the form of a square frame oriented along the directions of the [110] family, and the conductors at the points of contact to the corners of the square frame are made in the form of identical rectangles with sides parallel to the sides of the square frame and completely overlap the corners of the square frame of the strain gage with gaps between the sides of the conductors and the sides of the angle of the square frame of at least 1 alignment errors.

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