Production method for MEMS silicon film

Abstract

The invention discloses a production method for an MEMS silicon film. According to the production method, a silicon dioxide layer is used as an auto-stopping layer, and a method combining drying etching with wet etching is used, thus the silicon film with accurate thickness and size can be produced, and meanwhile the size of the device is also greatly reduced.

Description

technical field [0001] The invention relates to the technical field of semiconductor devices, in particular to a method for manufacturing a MEMS silicon film. Background technique [0002] Many MEMS devices require the use of silicon membranes. For example, a piezoresistive MEMS pressure sensor is composed of a silicon membrane and a stress-sensitive piezoresistor on the silicon membrane. When the silicon membrane is deformed under pressure, the piezoresistive resistance value is changed, and the pressure change can be obtained by measuring the resistance change through a bridge. The size and thickness of the silicon film directly determine the sensitivity of the device. How to prepare a silicon film with precise size and thickness has become one of the key technologies for the development and practical application of MEMS devices, and thus a variety of silicon film preparation technologies have been developed. The simplest technique for preparing a silicon film is to dire...

AI Technical Summary

Problems solved by technology

This technique is simple but has many disadvantages

For example, the thickness of the starting silicon wafer is not uniform, which will have a great influence on the thickness of the resulting silicon film

If there are impurity gradients or defects in the silicon wafer, it will also cause different etching rates in different regions of the silicon wafer, which will also lead to inaccurate size and thickness of the silicon film

At the same time, there are large errors in the measurement of silicon wafer thickness and etching depth

So with this technique, it is difficult to obtain a silicon film with precise thickness and size

In addition, the etching cavity etched by KOH or TMAH is an inverted trapezoid, and the production of a silicon film of the same size requires additional device space

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