JPH06160218A - Manufacture of semiconductor sensor - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a semiconductor sensor which can improve yield by reducing the possibility of damaging a substrate. CONSTITUTION:A gauge resistor 2 according to an impurity diffusion layer is formed on one main surface of a silicon substrate 1 and an etching mask 3b by a material which is capable of aode joint for glass is subjected to pattern formation at the peripheral part of the other main surface of the substrate 1. Then, after a sensor chip with a thin diaphragm 4 is formed at a region where the gauge resistor 2 is formed by etching the silicon substrate 1, the peripheral thick part of the obtained sensor chip is subjected to anode joint to a pedestal glass 5 while leaving the edge mask 3b.

Description

Detailed Description of the Invention [Industrial applications]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor sensor which detects pressure, acceleration and the like by using a gauge resistance formed by a semiconductor diffusion layer.

[0002]

2. Description of the Related Art Semiconductor sensors such as pressure sensors and acceleration sensors using a silicon substrate are known. In this type of semiconductor sensor, a gauge resistance is formed by an impurity diffusion layer on a silicon substrate, the back surface of the substrate in the area where the gauge resistance is formed is processed as a thin diaphragm by etching, and a pedestal glass is formed on a peripheral thick portion. It is attached. The pedestal glass is usually attached by anodic bonding between the silicon substrate and the glass.

In the etching process of the back surface of the silicon substrate in such a conventional semiconductor sensor, anisotropic etching using a KOH solution using a silicon nitride film as an etching mask is usually utilized. In this case, in order to perform anodic bonding between the silicon substrate and the glass, a silicon nitride film peeling step is required thereafter.

[0004]

As described above, in the conventional method, the peeling step of the etching mask material is indispensable, and the peeling step is necessary after the thin diaphragm is processed and the substrate strength is lowered. However, there is a problem in that the substrate is likely to be damaged and thus the yield of the semiconductor sensor is reduced. It is an object of the present invention to provide a method for manufacturing a semiconductor sensor that can reduce the possibility of substrate damage and improve the yield.

[0005]

According to the method of manufacturing a semiconductor sensor of the present invention, a gauge resistance is formed by an impurity diffusion layer on one main surface of a semiconductor substrate, and an anode for glass is formed on the periphery of the other main surface of the substrate. After forming an etching mask of a material that can be bonded, and etching the substrate using this etching mask to form a sensor chip having a thin diaphragm in the region where the gauge resistance is formed,
It is characterized in that the peripheral thick portion of the obtained sensor chip is anodically bonded to the base glass while leaving the etching mask.

[0006]

According to the present invention, the thin diaphragm is etched using the etching mask material made of a material capable of anodic bonding to glass, and the mask material peeling step after the processing is unnecessary. Therefore, the chances of substrate damage are reduced compared to the conventional case, and the yield of semiconductor sensors can be improved.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a manufacturing process of a semiconductor pressure sensor according to an embodiment of the present invention. As shown in FIG. 1A, a gauge resistor 2 is formed on one main surface of a silicon substrate 1 by impurity diffusion. Then, on the other main surface of the silicon substrate 1, as a mask material for anisotropic etching of silicon,
A mask material film 3a capable of anodic bonding to glass is formed.

As the mask material film 3a, a metal or a metal compound having resistance to etching in the next etching step is suitable. Specifically, chromium or chromium oxide is used. In addition to these, any material having etching resistance, good adhesion to a substrate, and capable of anodic bonding to glass can be used as the mask material film 3a. For example, KOH is used for anisotropic etching. If used, nickel, tungsten, zirconium or the like can be used.

After that, the mask material film 3a is selectively etched and left as an etching mask 3b only on the peripheral portion of the substrate as shown in FIG. 1 (b). Then, the silicon substrate is anisotropically etched with a KOH solution using the etching mask 3b left in the peripheral portion, and as shown in FIG. 1 (c), the thin diaphragm 4 is formed in the region where the gauge resistor 2 is formed. Forming a sensor chip having.

Thereafter, as shown in FIG. 1 (d), the sensor chip thus formed is left with the etching mask 3b, and the peripheral thick portion where the etching mask 3b is left is directly attached to the base glass 5. Anodic bonding. The anodic bonding is performed, for example, by heating in a vacuum to about 500 ° C., with the silicon substrate side as a positive electrode and the pedestal glass side as a negative electrode, about 600 V
The voltage is applied.

According to this embodiment, the step of removing the etching mask after the step of processing the thin diaphragm is unnecessary, and the possibility of damage to the sensor chip is reduced as compared with the conventional case.

[0012]

As described above, according to the present invention, by using the etching mask capable of anodic bonding with the pedestal glass at the time of processing the thin-walled diaphragm portion, the step of removing the etching mask is unnecessary, and the semiconductor sensor Yield can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a manufacturing process of a semiconductor pressure sensor according to an embodiment of the present invention.

[Explanation of reference numerals] 1 ... Silicon substrate, 2 ... Gauge resistance, 3a ... Mask material film, 3b ... Etching mask, 4 ... Thin diaphragm,
5 ... Pedestal glass.

Claims (1)

[Claims] 1. A step of forming a gauge resistance by an impurity diffusion layer on one main surface of a semiconductor substrate, and an etching mask made of a material capable of anodic bonding to glass is formed on a peripheral portion of the other main surface of the substrate. A step of etching the substrate using this etching mask to form a sensor chip having a thin diaphragm in a region where the gauge resistance is formed, and a state in which the etching mask is left in the peripheral thick part of the sensor chip. And a step of anodic bonding to a pedestal glass.