JPH02272339A - Semiconductor pressure sensor - Google Patents

Abstract

PURPOSE:To improve the pressure-proof property and to prevent a seal from being broken by oil or chemicals like a solvent by soldering a laminated film of chromium, platinum, and gold, which is formed on the lower face of a pedestal for pressure-sensitive element made of a heat resisting glass, to stem to stick this pedestal. CONSTITUTION:A chromium film 3, a platinum film 4, and a gold film 5 are sputtered on the lower face of a pedestal 2 made of a heat resisting glass to form a laminated film 6. The pedestal 2 is soldered to a stem 7 by this laminated film 6 as shown by 8, and a pressure-sensitive chip 9 is joined to the upper face of the pedestal 2 by anode junction, and a diaphragm 10 where a bridge circuit of resistances is formed for this pressure-sensitive chip 9 is connected to lead pins 12 by gold wires 11. A through hole 14 connected to a pressure chamber 13 of the pressure-sensitive chip 9 is formed in the center part of the pedestal 2, and the stem 7 is provided with a pressure introduction hole 15 correspondingly to the through hole 14.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to a semiconductor pressure sensor that utilizes a semiconductor piezoresistance effect, and more specifically, a pressure-sensitive chip pedestal is fixed on a stem, and the pedestal is The present invention relates to an electronic pressure sensor having a pressure-sensitive chip bonded to its upper surface.

(B) Prior Art A semiconductor pressure sensor that senses fluid pressure such as air has a pedestal 32 fixed on a stem 31 as shown in FIG. Mount chip 33,
A diaphragm 34 having a resistor bridge circuit formed on the pressure sensitive chip 33 is connected to lead pins 36 and 36 by gold wires 35 and 35.

Further, the pressure sensitive chip 33 has a pressure chamber 37, and a pressure introduction port 38 is provided in the stem 31 correspondingly.

In this case, conventionally, a glass pedestal 3 is used as shown in Fig. 3A.
2 and the stem 31 with an adhesive 39, or seal the space between the pedestal 32 and the stem 31 with an O-ring 40 as shown in Figure 3, or attach the pedestal 32 to the A method of joining the pressure chips 33 by soldering 41 has been adopted.

(c) Problems to be Solved by the Invention However, those that adhesively fix the pedestal 32 and the stem 31 and those that seal with an O-ring have the disadvantage of poor airtightness. It is sensitive to chemicals and swells, reducing bonding strength.

Further, in the case where the pedestal 32 and the pressure sensitive chip 33 are soldered together, the soldering must be performed one by one for each pressure sensitive chip 33, which has the drawback of poor mass productivity and yield.

In view of the above-mentioned problems, this invention is capable of fixing a pedestal to a stem with high airtightness and bonding force, and also enables bonding of a pedestal and a pressure-sensitive chip on a wafer-by-wafer basis, thereby increasing mass productivity and yield. The purpose is to provide sensors.

(d) Means for solving the problem In this invention, a pressure-sensitive chip pedestal made of Pyrex glass is fixed by soldering a laminated film of chromium, platinum, and gold formed on the lower surface onto the stem. The present invention is also characterized by a semiconductor pressure sensor in which a pressure-sensitive chip is anodically bonded to the upper surface of the pedestal.

(E) Function According to this invention, since the pedestal has a laminated film of chromium, platinum, and gold formed on the lower surface of the pedestal and is soldered to the stem, it has better pressure resistance than an O-ring or adhesive seal structure. The seal is not damaged by chemicals such as oil or solvents.

In addition, since the pressure-sensitive chip is fixed to the pedestal by anodic bonding,
The bonding can be performed in units of semiconductor wafers, and by cutting the wafers into chips after bonding each wafer, a large number of pressure sensor chips can be obtained at once.

(f) Effects of the Invention Accordingly, a semiconductor pressure sensor can be obtained that has good airtightness, is resistant to chemicals such as oil and solvents, and can reduce costs by improving mass productivity and yield.

(g) Examples An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view of a semiconductor pressure sensor 1 according to the present invention, in which a chromium film 3 is formed on the lower surface of a pedestal 2 made of Pyrex glass.
, a platinum film 4 and a gold film 5 are sputtered to form a laminated film 6, the pedestal 2 is soldered 8 to the stem 7 using this laminated film 6, and a pressure sensitive chip 9 is bonded to the upper surface of the pedestal 2 by anodic bonding. , a diaphragm 1o in which a bridge circuit made of resistors is formed on this pressure-sensitive chip 9 is connected to a gold wire 1.
1.11 is connected to lead pin 12.12.

Furthermore, a through hole 14 connected to the pressure chamber 13 of the pressure sensitive chip 9 is formed in the center of the pedestal 2, and a pressure introduction port 15 is provided in the stem 7 in correspondence with the through hole 14.

The pressure sensor 1 having such a configuration is manufactured through the following steps. That is, a first step of sequentially forming the above-described chromium film 3, platinum film 4, and gold film 5 on one surface of the Pyrex glass pedestal 2, and after the first step, a large number of layers are formed on the other surface of the pedestal 2. A second step is to bond the semiconductor wafers 98 on which the diaphragms 10 are formed by anodic bonding to produce a bonded body 16 as shown in FIG. 2, and to cut the bonded body 16 obtained in the second step. and a fourth step of fixing this chip-shaped assembly (pressure sensor chip) to the stem 7 by soldering 8.

In addition, to give an example of the above process, a glass plate, for example Pyrex #7740° #7070 manufactured by Corning, is coated with a chromium film of 500A', a platinum film of 2000A', and a gold film of 6000A'.
The layers are sequentially laminated to a thickness of A'.

For this lamination, vapor deposition, sputtering, plating, etc. are used, or they are used in combination.

In addition, the adhesive strength of chromium Cr with AI and 5i02 is 750 g/m rd compared to 600 g/m rd of titanium Ti.
It has a high mrd and is easily sputtered. Therefore, by employing the chromium film 3, the adhesive strength between the laminated film 6 and the pedestal 2 is increased, the etching rate is fast, and the process can be shortened. Moreover, since chromium is a cheap raw material, costs can be reduced.

Furthermore, as is well known, the semiconductor pressure sensor detects pressure by a change in resistance value based on the curvature of the diaphragm 10, but it is possible to reduce changes in stress acting on the diaphragm 10 due to various causes other than the pressure caused by the pressure medium. Therefore, the pedestal 2 made of Pyrex glass described above is used. The base 2 is therefore a silicon semiconductor or borosilicate glass having the same coefficient of thermal expansion as the diaphragm 10.

As is clear from the above description, according to this embodiment, the pedestal is soldered 8 to the stem 7 by the laminated film 6 of the chromium film 3, platinum film 4, and gold film 5, which improves airtightness and prevents oil and The influence of chemicals such as solvents can be eliminated.

In addition, as shown in Fig. 2, the pedestal 2 is placed in units of 9A of semiconductor wafers.
Since a large number of pressure sensor chips can be manufactured at one time by anodic bonding and then cutting the bonded body 16, mass production becomes possible.

Note that the present invention is not limited to the configuration of the above-described embodiment.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a front view of a semiconductor pressure sensor, and FIG. 2 is a sectional view of a bonded body showing the process of manufacturing the pressure sensor. Figures 3A, 3B and 3C are cross-sectional views of a conventional pressure sensor, respectively. 1... Semiconductor pressure sensor 2... Pedestal 3... Chrome film 4... Platinum film 5... Gold film
6... Laminated film 7... Stem 8.
...Solder 9...Pressure sensitive chip Figure 1 Pressure 77t Figure 3 Front entrance of the conventional pressure 77 knob External view (A) (B) Cross-sectional view of the tension assembly (C)

Claims (1)

[Claims] (1) A pressure-sensitive chip pedestal made of Pyrex glass is fixed by soldering a laminated film of chromium, platinum, and gold formed on the bottom surface onto the stem, and a pressure-sensitive chip is attached to the top surface of the pedestal. A semiconductor pressure sensor with anodic bonding.