Deep Si etching method

Abstract

The present invention discloses a deep Si etching method. The method comprises the steps of: providing a silicon wafer coated with a graphical mask layer, and etching the surface of the silicon waferwithout being coated with the mask layer to form an etching surface and a side wall basically perpendicular to the etching surface. The method further comprises repeated and circulated passivation step, first etching step and second etching step until a predetermined etching depth is obtained. With the increasing of the number of times of cycle periods, at least one of conditions (1)-(3) is met that: (1) the deposition time of the passivation step is increased with the increasing of the number of times of the cycle periods, (2) the plate electrode power in the second etching step is increasedwith the increasing of the number of times of the cycle periods, and (3) the air pressure in the second etching step is increased with the increasing of the number of times of the cycle periods.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a deep silicon etching method. Background technique [0002] Micro-electromechanical system sensors are more and more widely used in the fields of automobiles, mobile phones and smart wearable devices, and micro-electromechanical system (MEMS) technology with bulk silicon technology as the core is developing particularly rapidly. The development of high aspect ratio silicon etching technology has greatly improved the sensitivity of micro sensors and actuators. Compared with the surface silicon process, the bulk silicon process with the deep silicon etching process as the core can obtain a larger detection capacitance and a more sensitive mass structure, which improves the resolution and sensitivity of the MEMS sensor. [0003] The current deep silicon etching system is realized by Bosch process. In the deep etching system, there is a problem that the etching rate decr...

AI Technical Summary

Problems solved by technology

In the deep etching system, there is a problem that the etching rate decreases as the width of the etching groove becomes narrower. This phenomenon is called the lag effect. Sometimes even in the etching of a narrow etching groove, the etching rate gradually decreases with the increase of the etching depth. reduce to zero

At the same time, as the etching progresses, the sidewall of the opening on the narrow etching groove is severely damaged, the opening on the etching becomes wider, and the loss of line width increases, resulting in a decrease in the etching aspect ratio.

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