JPH01301178A - Manufacture and assembly of semiconductor acceleration sensor - Google Patents

Abstract

PURPOSE:To prevent a breakage from a thin (groove) part by forming the groove part in the reverse surface of a cantilever element part formed on a wafer, and then sticking a heat-decomposed resin layer on its reverse surface and joining a cantilever which is divided into individual parts with a package. CONSTITUTION:Many cantilever element parts 1A are formed on the semiconduc tor wafer 5 and the groove part 1a is formed in the reverse surface by etching continuously in an X-axial direction. Further, a part which becomes the fixed end part of each element part 1A is removed and a heat-decomposed resin (e.g. poly (alpha-methyl styrene) layer 11 is stuck on the reverse surface by coating. The wafer 5 in this state is divided into many pieces along respective cutting lines 6 and a pedestal 12 is joined with the fixed end of a divided cantilever 1 with, for example, an epoxy resin adhesive. The sensor which is constituted as mentioned above is joined and fitted across the pedestal 12. Then the resin layer 11 is heated (e.g., 180 deg.C) and removed by sublimation. Thus, the groove part 1a is protected, so the sensor is prevented from being broken when carried or fitted to the package.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing and assembling a piezoresistive semiconductor acceleration sensor using semiconductor cantilever beams, and in particular to a method for preventing damage to each cantilever beam divided from a wafer. related to.

[Conventional technology]

FIG. 3 is a perspective view of a main part of a conventional semiconductor acceleration sensor disclosed in, for example, Japanese Unexamined Patent Publication No. 62-221164. In the figure, reference numeral 1 denotes a cantilever beam made of silicon, with a groove 1a provided on the back surface near the fixed end, and a thin wall 1b formed locally to increase sensor sensitivity. A plurality of piezoresistors 2 are provided on the surface of this thin portion 1a by thermal diffusion, etc., and are configured as a bridge circuit.

A method of manufacturing the semiconductor acceleration sensor will be explained with reference to FIG. A large number of support elements are formed on a silicon wafer 5. Each of these element portions IA has a piezoresistor 2 shown in FIG. 3 formed on its front surface to form a bridge circuit, and grooves 1 &
It is formed continuously in the axial direction. Cuts fa6 are made in the wafer 5 in this state in both the vertical and horizontal directions to divide each supporting element section.

The wafer 5 thus formed is divided into a large number of pieces along each score line 6 by a dividing means (not shown), thereby producing a large number of cantilever beams 1 as shown in FIG.

This cantilever beam 1 is joined to a package pedestal (not shown) for assembly.

[Problem to be solved by the invention]

In the conventional method for manufacturing and assembling a semiconductor acceleration sensor as described above, a large number of cantilever element parts are formed on the wafer 5, a groove part 1a is formed on the back surface, and the wafer is divided into each cantilever beam 1. The thickness of the thin part 1b of the cantilever beam 1 is, for example, 10~
The thickness is 80 μm, which is very thin, and stress is concentrated in the groove portion 1a, resulting in extremely low mechanical strength. For this reason, there is a problem in that it is easily damaged during transportation or assembly into a package.

This invention was made in order to solve the problems of the conventional method of manufacturing and assembling semiconductor acceleration sensors.
The object of the present invention is to obtain a method for manufacturing and assembling a semiconductor acceleration sensor that eliminates damage to semiconductor cantilevers.

[Means to solve the problem]

The method for manufacturing and assembling a semiconductor acceleration sensor according to the present invention is to form a groove on the back surface of a cantilever element formed on a wafer in the manufacturing process, and then to attach a heat splitting resin layer to the back surface to separate each piece into individual pieces. After the support beam is bonded to the package via the pedestal, it is heated to sublimate and remove the heat splitting resin layer.

[Effect]

In this invention, a pyrolytic resin layer is attached to the back surface of each divided cantilever beam to protect the groove portion, so that the cantilever beam is not damaged from the groove portion during transportation or assembly.

〔Example〕

FIG. 1 is a schematic perspective view of an embodiment of a semiconductor acceleration sensor manufactured by the manufacturing and assembly method according to the present invention.

In the figure, 1, Iallb, and 2 are the same as those in the conventional system, and their explanation will be omitted. The back side of the cantilever beam 1 is coated with a pyrolytic resin (for example, polyalphamethylstyrene) M.
ll is attached to protect the groove 1&. ] 2 is a pedestal made of silicon, for example, and bonded to the fixed end of the cantilever beam 1 with a bonding material (for example, gold-silicon eutectic alloy);
It is joined to a package (not shown) during assembly.

The manufacture of one part of the above-mentioned cantilever beam will be explained with reference to FIG. A large number of cantilever element portions 1 are formed on a semiconductor wafer 5 such as silicon.
Form people. A piezoresistor 2 shown in FIG. 1 is formed on the surface of each of these element parts, forming a bridge, and a groove 1a is etched on the back surface.
It is formed continuously in the axial direction. In addition, on the back side, a pyrolytic resin layer 11 is provided, except for the portion that becomes the fixed end of each element.
Attach by coating etc.

Incision lines 6 are made in the vertical and horizontal directions on the surface of the wafer 5 in this state to divide each supporting element element.

The thus processed wafer 5 is divided into a large number of pieces along each score line 6 by a dividing means (not shown), and as shown in FIG. Many burrs 1 are formed. A pedestal 12 is joined to the fixed end of this cantilever beam 1.

The acceleration sensor configured in this manner is attached to a package (not shown) by joining it via the pedestal 12. Next, the pyrolytic resin layer 11 is sublimated and removed by heating (for example, 180° C.).

In this way, since the cantilever beam 1 is formed on the wafer 5, the groove portion 1, which has low mechanical strength, is protected by the pyrolytic resin layer 11 on the back side, making it difficult to handle during transportation, etc.
This prevents damage during installation to the package, etc.

〔Effect of the invention〕

As described above, according to the present invention, a pyrolytic resin layer is attached to the back surface of a semiconductor cantilever beam to protect the groove, and after the fixed end of the cantilever beam is bonded to a package, heating is performed to form a pyrolytic resin layer. Since the cantilever beam is removed, damage to the thin wall portion during transportation and assembly is prevented, and handling is facilitated.

[Brief Description of the Drawings] Fig. 1 is a schematic perspective view showing an embodiment of a semiconductor acceleration sensor according to the manufacturing and assembly method of the present invention, and Fig. 2 (a) and (b) show the acceleration of Fig. 1. A plan view and a front view of a wafer for manufacturing a sensor, FIG. 3 is a schematic perspective view of a semiconductor acceleration sensor manufactured by a conventional manufacturing and assembly method, and FIGS. 4(a) and (b) are a diagram of the acceleration sensor of FIG. FIG. 2 is a plan view and a front view of a wafer to be manufactured. In the figure, 1 is a semiconductor cantilever, 1a is a groove portion, 1b is a thin wall portion, 2 is a piezoresistor, 5 is a semiconductor wafer, 11 is a pyrolytic resin layer, and 12 is a pedestal. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] A groove is provided on the back surface near the fixed end of the semiconductor cantilever beam, and the upper part is made into a thin-walled portion, and a plurality of piezoresistors are formed on the surface of this thin-walled portion to form a bridge circuit. Manufacturing and assembly of a semiconductor acceleration sensor, characterized in that a pyrolytic resin layer is attached to the cantilever except for the fixed end, the cantilever beam is fixed to the package via the pedestal at the fixed end, and the decomposed resin layer is sublimated and removed by heating. Method.