JPS61234572A - Pressure sensor - Google Patents

Abstract

PURPOSE:To prevent the exchange in characteristics even if a semiconductor chip is curved by the change in ambient temperature, by forming a groove in the lower surface of the thick part of the semiconductor chip so as to surround the thin diaphragm between a thin film diaphragm and an integrated circuit. CONSTITUTION:When ambient temperature is changed, a semiconductor chip 20 is curved together with a base seat 30 due to the difference in thermal expansion coefficients of the semiconductor chip 20 and the base seat 30. A groove 23 is formed in the semiconductor chip 20. Since the part of the groove 23 is thin, the chip is largely curved at the part of the groove 23. Stress is concentrated at a part where the thickness changes from a thin shape to a thick shape, and a bent shape is formed. Therefore, a thick part 22 at the outside of the groove 23 is hardly curved. As a result, the wiring in an amplifier transmitter 25 is not broken and strain is not applied to a transmitter (not shown in the Figure) in the amplifier transmitter 25. Therefore the amplification factor is not changed.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention involves forming a thin diaphragm in the center of a semiconductor chip, and surrounding the thin diaphragm with an IC (
The present invention relates to an rc pressure sensor formed with an integrated circuit.

<Conventional technology> Recently, IC1 has been installed around the thin diaphragm of semiconductor chips.
For example, IC pressure sensors equipped with amplifiers and temperature compensation circuits are being developed. As shown in FIGS. 4 and 5, a recess is provided in the center of the lower surface of the semiconductor chip 10 to form a thin-walled diaphragm 11, and the lower surface of the thick-walled portion 12 around the diaphragm 11 is attached to a pedestal 13 with a low melting point. They are joined by glass 14. Further, a strain gauge 15 is formed on the thin-walled diaphragm 11, and an amplifier 16 for amplifying the output voltage of the strain gauge 15 is formed on the upper surface of the thick-walled portion 12.

<Problems to be solved by the invention> The above-mentioned rc pressure sensor has the advantage of being miniaturized because the amplifier is integrated into an IC, and also has the advantage of being resistant to noise because the output voltage of the strain gauge 15 is immediately amplified. .

However, since the semiconductor chip 10 and the pedestal are made of materials with different coefficients of thermal expansion, when the surrounding temperature rises, the semiconductor chip 10 curves as shown by the dotted line A in FIG. When the temperature drops, the semiconductor chip 10 curves as indicated by the dotted line B. At this time, the thick portion 12 is also slightly curved, so that there is a risk that extremely thin wiring within the amplifier 16 may be cut or that distortion may be applied to the transistor within the amplifier 16, thereby changing the amplification degree.

<Means for Solving the Problems> The present invention has been made in order to solve the above-mentioned problems, and includes a structure in which a thin diaphragm is placed between the thin diaphragm and the integrated circuit on the lower surface of the thick part of the semiconductor chip so as to surround the thin diaphragm. It has grooves formed therein.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIGS. 1, 2, and 3, reference numeral 20 denotes a semiconductor chip made of silicon, and this semiconductor chip 20 has a thin diaphragm 21 formed by providing a recess in the center of the lower surface. A thick portion 22 that is relatively thicker than the thin diaphragm 21 is formed around the thin diaphragm 21, and the thin diaphragm 2 is formed on the lower surface of the thick portion 22.
A groove 23 is formed to surround 1. A strain gauge 24 is formed on the upper surface of the thin-walled diaphragm 21, and an amplified oscillator 25 is formed on the upper surface of the thick-walled portion 22 outside the groove 23. The strain gauge 24 and the amplified oscillator 25 are connected by an enclosure wiring.

In addition, as another embodiment, the IC is not limited to the amplified oscillator 25, but may be one using a temperature compensation circuit or a voltage-frequency converter.

Reference numeral 30 denotes a pedestal made of glass or ceramics, and the lower surface of the thick wall portion 22 of the pedestal 30 has a low melting point glass 31.
It is glued by. Note that the lower surface of the thick portion 22 may be bonded to the pedestal 30 by an anodic bonding method.

Next, the operation will be explained based on the above-described configuration.

When pressure is applied to the thin diaphragm 21 from above, the strain gauge 24 is distorted and the output voltage changes, and this output voltage is amplified by the amplification oscillator 25 and sent to an external device.

When the ambient temperature changes, the difference in thermal expansion coefficient between the semiconductor chip 20 and the pedestal 30 causes the semiconductor chip 2 to expand along with the pedestal 30.
0 is curved. At this time, since the groove 23 is formed in the semiconductor chip 20 and the groove 23 portion is thin, the groove 23
The thick portion 22 outside the groove 23 hardly curves because the stress is concentrated and bent at the portion where the wall changes from thin to thick. As a result, there is no risk that the wiring within the amplified oscillator 25 will be cut or that the amplification degree will change because no distortion is applied to the transistors in the circuit within the amplified oscillator 25.

In the above embodiment, one groove 23 is provided, but a plurality of grooves 23 may be provided.

<Effects of the Invention> As described above, according to the present invention, a groove is formed on the lower surface of the thick portion of the semiconductor chip between the thin film diaphragm and the integrated circuit so as to surround the thin diaphragm, so that the semiconductor chip is not affected by changes in ambient temperature. Even if it curves, the groove part is largely curved and the stress is concentrated in the part where the wall changes from thin to thick, resulting in the shape of bending, so the thick part outside the groove hardly curves. Therefore, there is an advantage that there is no possibility that the wiring in the integrated circuit will be cut or that the transistors in the integrated circuit will be distorted, so that the characteristics will not change.

[Brief explanation of drawings]

1 to 3 show embodiments of the present invention,
Figure 1 is a longitudinal sectional view, Figure 2 is a sectional view taken along the line ■-■ in Figure 1, Figure 3 is a plan view, and Figures 4 and 5 are conventional I
4 is a longitudinal sectional view and FIG. 5 is a plan view of the C pressure sensor. 20... Semiconductor chip, 21... Thin diaphragm, 22... Thick wall portion, 23... Groove, 24... Strain gauge, 25... Amplified oscillator.

Claims (1)

[Claims] (1) The central part of the lower surface of a plate-shaped semiconductor chip is recessed to form a thin-walled diaphragm, the lower surface of the thick-walled part around the diaphragm is adhered to a pedestal, and an integrated circuit in which at least an amplifier is integrated is formed on the upper surface. A pressure sensor characterized in that a groove is formed on the lower surface of the thick portion between the thin diaphragm and the integrated circuit so as to surround the thin diaphragm.