JPH0476960A - Pressure detector - Google Patents

Abstract

PURPOSE:To make stable operation possible even under high atmospheric temperature by providing with gold wirings connecting between diffused resistors on a semiconductor diaphramg insulation layer and electrode pads, those connecting between diffused resistors, those connecting the electrode pads and lead posts and homogeneous gold conductors. CONSTITUTION:A silicon oxide underlayer (SiO2) 12 is accumulated on the N-type silicon (Si) substrate 11, and polysilicon layer 15 is accumulated on the insulation layer 14. When the polysilicon layer is scanned by argon laser from upper part, it becomes molten and then recrystallized as a single crystal. Polysilicon layer 15, except for parts to be used as diffused resistors, is removed by etching. Non-etched polysilicon layer parts 5 are formed as diffused resistors 15a-15d by implanting some impurity. Protection layer 20 is established with glass coating over the whole surface area gold wiring 19 being formed in the front and parts other than gold wiring 19 corresponding to wiring area as well as resist layer 24 being removed by etching.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure detection device for detecting pressure such as engine exhaust pressure, for example.

[Conventional technology]

FIG. 4 is a plan view showing a conventional pressure detection device, and FIG. 5 is a sectional view thereof. In the figure, 1 is a semiconductor diaphragm in which the central part of the silicon substrate is removed to form a thin part 1a; 2 is a semiconductor diaphragm;
3 is an insulating layer formed on the surface of the semiconductor diaphragm 1, 3 is a polycrystalline silicon layer formed on the insulating layer 2, and 4 is a plurality of diffusions formed by implanting impurities (poron) into a part of the polycrystalline silicon layer 3. 5 is an insulating layer formed on the surface of the polycrystalline silicon layer 3; 6 is an aluminum wiring that penetrates the insulating layer 5 and connects the diffused resistor 4 and the electrode pads and between the diffused resistors 4; 8 is an electrode; This is a gold wire that connects the pad 7 and the lead post 9.

Next, I will explain the operation. When external pressure such as engine exhaust pressure acts on the semiconductor diaphragm 1 from the direction of the arrow,
It deforms according to the magnitude of the pressure, and this deformation changes the electrical signal output from the diffusion resistor 4 to the lead post 9 via the aluminum wiring 6, the electrode pad 7, and the gold wire 8, and this electrical signal changes. The pressure is detected by

[Problems to be Solved by the Invention] Since the conventional pressure detection device is configured as described above, there is a bond between different metals of the aluminum wiring 6 and the gold wire 8 in the electrode pad 7, which is particularly difficult to solve in a high-temperature atmosphere. There was a problem with unstable operation due to differences in corrosion between different metals inside.

This invention was made to solve the above-mentioned problems, and an object thereof is to obtain a pressure detection device that can operate stably even in a high-temperature atmosphere.

[Means to solve the problem]

The pressure detection device according to the present invention includes a gold wire connecting between a diffused resistor and an electrode pad provided on an insulating layer of a semiconductor diaphragm and between the diffused resistors, and a gold wire connecting between the electrode pad and the lead post. and a gold wire of the same kind of metal.

[For production]

The pressure detection device according to the present invention can operate stably even in a high temperature atmosphere by bonding the same metals of gold wiring and gold wire to the electrode pad.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, in which the same parts as in FIGS. 4 and 5 are given the same reference numerals and redundant explanations are omitted, 14 is an insulating layer formed on the surface of the semiconductor diaphragm 1, and 15a to 15d are insulating layers. Diffused resistor provided on layer 14, 18 is diffused resistor 15a
~15 (an insulating layer covering l, 19 is a gold wiring that penetrates the insulating layer 13 and connects the diffused resistors 15a to 15d and the electrode pad 7, and also connects the diffused resistors 15a to 15d to each other to form a bridge configuration. , 20 is a surface protective layer formed on the gold wiring 19.

Next, the operation of the above embodiment will be explained. When the semiconductor diaphragm 1 is deformed by receiving external pressure from the direction of the arrow,
Due to this deformation, the diffused resistor 1 is connected in a Buri-Noji configuration.
Electrical signals from 5a to 15b also fluctuate, and pressure can be detected based on this fluctuation.

Hereinafter, one example of the method for manufacturing the pressure detection device of the present invention will be described in the third section.
The diagram will be explained. An underlying oxide layer (SiO□) 12 with a thickness of 500 nm is formed on an N-type silicon (Si) substrate 11 (5T-1), and a nitride layer (SiJ4) 13 with a thickness of 800 nm is deposited on the underlying oxide layer. (ST-2).

The nitride layer 1 is left with a portion corresponding to the seed portion 11a.
3. The underlying oxide film 12 and the N-type silicon substrate 11 are sequentially etched away (ST-3 to 5T-5). in this case,
The etching amount H1 of the N-type silicon substrate 11 is approximately 3,500 Tb.

Subsequently, after removing the resist 21 on the remaining nitride layer 13 (ST-6), an oxide layer 14 with a thickness T=1.1 μm is formed on the N-type silicon substrate 1 by thermal oxidation (ST-7).
), the remaining nitride layer 13 is removed, the remaining underlying oxide layer 12 is removed, and the oxide layer 14 is removed.
．． The surface is flattened by etching away approximately 1 μm (S
T-8, 5T-9).

Thereafter, a polysilicon layer 15 is deposited to a thickness of 5000 on the oxide layer 14 (5T-10), and a nitride layer 1 is deposited thereon.
6 to a thickness of 500 mm (5T-11), and this nitride layer 1
The resist 22 is etched away so that 6 remains on the stripe to form an antireflection layer 17 (ST-12, 5
T-13).

Subsequently, a laser (not shown) (argon laser) is irradiated and scanned from above to melt the polysilicon layer 15 and then recrystallize it into a single crystal (ST-14). After that, the antireflection layer 17 and the nitride layer 16 are removed (ST-15
).

The recrystallized polysilicon layer 15 is etched away together with the resist 23, leaving a portion that will become a diffusion resistance (ST-16, 5T-17).

Impurities (for example, boron) are added to the remaining polysilicon layer 5.
is implanted to form a plurality of diffused resistors 15a to 15d (ST
-18). As a result, a plurality of diffused resistors can be formed on the insulating layer, which is an oxide layer, in an electrically isolated state, and then an oxide layer 14 is formed to cover the diffused resistors.
A high temperature oxide layer 18 is deposited on the entire surface (ST-19).

Next, after removing the high-temperature oxide layer 18 that will become the contact together with the resist layer 23 (ST-20
), the resist layer 23 is removed by etching (ST-21
). After that, a gold wiring layer 19 is formed on the front surface.
2), leaving the gold wiring layer 19 corresponding to the wiring area,
After removing other parts and the resist layer 24 by etching (ST-23, 5T-24), a protective layer 20 by glass coating is applied to the entire surface (ST-25).

Thereafter, a part of the protective layer 20 is removed by etching to form the electrode pad 7, and the back surface of the N-type silicon substrate 1 is polished to form a wafer with a desired thickness.
^u) Form 25 (ST26). Then, remove the gold 25 and resist 26 from the portion that will become the diaphragm (5T-27°5T-28), and use the remaining gold 25 as a mask to remove the back surface of the N-type silicon substrate 11 by etching to form the semiconductor diaphragm 1. Forming the thin part 1a (
ST-29).

In addition, the above 5T-3, 5T-12, 5T-16゜5T-
Resist layers 21 to 24.26 in 23,5T-27
is applied during mask matching (pattern matching) for etching in each pre-stage. This will serve as a mask for etching.

By the above manufacturing method, a plurality of diffused resistors made of single crystal silicon can be formed on an insulating layer formed on a semiconductor silicon single crystal substrate in a state where they are electrically insulated from each other. As a result, thermal stress is alleviated even in high-temperature environments, reducing temperature drift and stabilizing operation.

〔Effect of the invention〕

As described above, according to the present invention, since the gold wiring and the gold wire are connected to the electrode pad, the same kind of metals are connected to the electrode pad.
This has the effect of providing an excellent pressure detection device that does not become unstable due to corrosion even in a high-temperature atmosphere.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a pressure detection device according to an embodiment of the present invention with the surface protective layer removed, FIG. 2 is a sectional view thereof, and FIG. 3 is an explanatory diagram showing a method for manufacturing the pressure detection device of the present invention. , FIG. 4 is a plan view of a conventional pressure detection device with the surface protective layer removed, and FIG. 5 is a sectional view thereof. 7 is an electrode pad, 8 is a gold wire, 9 is a lead post, 11 is a silicon substrate, 14 is an insulating layer, 15a to 15d are diffused resistors, 19 is a gold wiring, and la is a thin part. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Figure 1

Claims (1)

[Claims] A semiconductor diaphragm having a thin portion in the center, an insulating layer formed on the surface of the semiconductor diaphragm, a plurality of diffused resistors provided on the insulating layer corresponding to the thin portion, and each of the diffused resistors and an electrode pad. A pressure detection device comprising a gold wire connecting between the electrode pad and the lead post, and a gold wire made of the same metal as the gold wire connecting the electrode pad and the lead post.