JPH01143963A - Manufacture of semiconductor acceleration sensor - Google Patents

Abstract

PURPOSE:To package the packaging process of the number of the tips of one wafer by executing the packaging of a cover for protecting a sensor and a header and the charging of a buffer in a wafer process. CONSTITUTION:Respective wafers of a sensor part 1, a cover 2 and a header 3 covered with a nitriding silicon film 8 are bonded by a low melting point glass. To the film 8 of the surface of the wafer 2, a pattern is prepared for the purpose of etching for extracting an electrode. The silicon of the wafer 2 is etched from the surface up the film 8 of a back. To the film 8 of the surface of the wafer 2, holes 8a are formed in two or above. To the wafer 2, a buffer injecting hole 10 is formed. The film 8 of the surface of the wafer 2, a glass 5 and the film 8 of the surface of a wafer 1 are removed by a dry etching, and a bonding pad 11 is exposed. After the buffer is injected from the hole 10, a silicon gum 12, etc., is applied, and the hole 10 is closed. Next, a division for a sensor tip is executed, and the electrode pad of the tip and an external lead are connected by a wire bonding. A resin sealing is executed, and a package is made.

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Industrial Application) The present invention relates to the implementation of a semiconductor acceleration sensor,
It is used as an acceleration sensor for automobiles in anti-skid brake systems, etc.

(Prior art) As a prior art related to the present invention, Japanese Patent Application Laid-Open No. 59-9935
There is Publication No. 6.

This sensor uses the piezoresistive effect of single-crystal silicon, and as shown in Figure 5, the acceleration sensor chip 1
Header 3. It has a structure in which it is attached to a cover 2, and an epoxy compound 4 containing glass powder is sandwiched between the header, the cover, and the chip.

(Problems to be Solved by the Invention) However, the mounting method of the semiconductor acceleration sensor with the above structure is as follows: (2) Since the chips are mounted after being separated from the wafer, the number of man-hours required for assembly increases significantly.

There is a problem.

The technical object of the present invention is to reduce the number of man-hours required for assembling a header and a cover that serve as an overload protection device for a sensor chip of a semiconductor acceleration sensor.

[Structure of the invention]

(Means for solving the problem) The technical means for solving the above technical problem are as follows. That is, the sensor part and cover have a gauge beam and a weight made of semiconductor.

+11 In a method for manufacturing an acceleration sensor consisting of a header, the sensor portion coated with silicon nitride, the cover, and the header wafer are bonded using low-melting glass, (2) a pattern is formed for electrode extraction, Etch down to the silicon nitride film, which has an extremely slow etching rate, using a silicon etching solution, (3) form a hole for injecting a buffer, and (4) prepare the back surface of the cover wafer and the surface of the sensor part wafer for wire bonding. The silicon nitride film and the low-melting glass for bonding are removed by dry etching to expose the bonding pad, (5) a buffer is injected and sealed, (6) the electrode pad and external lead are connected using the wire bonding method. (7) A method for manufacturing an acceleration sensor using resin molding.

(Operation) The technical means operates as follows. In other words, by attaching the header and cover, which act as overload protection devices for the sensor chip, before the dicing process as in the above process, the chips can be divided into a large number of chips by dicing and at the same time be diced as is, just like a normal wafer. As a result, resin sealing is possible in the same way as normal ICs, and paired chips can be mounted on HICs and printed boards.

(Example) Examples will be described below.

Figures 1 (a) to (h) show the manufacturing process of this example, where ■ is a wafer on which an acceleration sensor is formed, 2 is a wafer on which a cover for overload protection and a buffer is formed,
3 is a wafer on which a header with sensor protection and overload protection functions is formed, and each wafer is
As shown in Figure (a), it is covered with a silicon nitride film 8,
6 is a weight, and 7 is a gauge beam.

(11) As shown in FIG. 1(B), the wafers 1, 2 and 3 are bonded together using low melting point glass (300°C to 400°C). 5 is an adhesive.

(2) As shown in FIG. 2(c), a pattern is formed on the silicon nitride film 8 on the surface of the wafer 2 for etching to take out the electrodes.

(3) As shown in FIG. 2(d), the silicon of the wafer 2 is etched from the front surface until it reaches the silicon nitride film 8 on the back surface of the wafer 2 using an etching solution such as KOH.

(4) As shown in FIG. 2(e), two or more holes 8a are formed in the silicon nitride film 8 on the surface of the cover wafer in order to form holes for injecting a buffering agent such as silicone oil.

(5) As shown in FIG. 2(c), a hole 10 for injecting a buffering agent such as silicon is formed by etching with KOH or the like.

(6) As shown in FIG. 2(g), silicon nitride film 8. on the back surface of cover wafer 2 is used for wire bonding.
The low melting point glass 5 and the silicon nitride film 8 on the surface of the sensor wafer are removed by dry etching using CF and +H2 gases to expose the bonding pad 11.

(7) As shown in FIG. 2 (H), after injecting a buffering agent such as silicone oil through the injection hole 10, the hole 10 is covered by applying silicone rubber 2 or the like.

Beta is performed to harden the rubber, etc., and then washed to remove oil, etc.

(8) Next, as shown in Figure 2, the sensor chips are divided into sensor chips by dicing in the same way as in the normal IC process, and the divided chips are bonded to the lead frame ■5, and the electrodes and leads of the chips are connected by wire bonding. do. 9
is a wire.

(9) As shown in FIG. 3, resin sealing is performed using a transfer molding machine to form a package as shown in 13.

In addition, as another embodiment, as shown in FIG.
4, it can be mounted as a bare chip or on a printed circuit board, 16 is a lead, 17 is a wiring pattern, and 18 is a sensor in a mounted state.

〔Effect of the invention〕

The present invention has the following effects. In other words, in this embodiment, compared to the conventional technology, since the protective cover for the sensor, the header, and the filling of the buffer are performed in the wafer process, the number of chips on - wafers can be mounted in one mounting process. In addition, since it can be handled in the same way as an IC chip compared to the conventional technology, it can be used for both resin mold type mounting and pair chip mounting.

[Brief explanation of the drawing]

Figures 1 (A) to (H) are explanatory diagrams of each process of this example, Figure 2 is an explanatory diagram of the divided sensor chip, Figure 3 is an explanatory diagram of the packaged product, and Figure 4 is an explanatory diagram of the other sensor chips. An explanatory diagram of the embodiment, and FIG. 5 is a cross-sectional explanatory diagram of a conventional example. l...Wafer, 2...Cover. 3...Header, 5...Adhesive. 8...Silicon nitride.

Claims (1)

[Scope of Claims] In a method for manufacturing an acceleration sensor comprising a sensor section having a gauge beam and a weight made of semiconductor, a cover, and a header, (1) each of the sensor section, cover, and header coated with silicon nitride; The wafer is bonded with low-melting glass, (2) a pattern is formed to take out the electrodes, and the silicon nitride film, which has an extremely slow etching rate, is etched using a silicon etching solution, (3) a hole is created for buffer injection. (4) To perform wire bonding, the silicon nitride film and low melting point glass for bonding on the back surface of the cover wafer and the sensor section wafer surface are removed by dry etching to expose the bonding pad, (5) A method for manufacturing an acceleration sensor, which includes injecting a buffering agent through an injection hole, then sealing it, (6) connecting an electrode pad and an external lead using a wire bonding method, and (7) performing resin molding.