A method for etching a silicon substrate by a Bosch process

Abstract

The invention provides a method for etching a silicon substrate in a BOSCH process. For a deposition step and an etch step, two groups of gas enter a process chamber alternately. Under the premise that there is no need to adjust the response speed of an MFC (Mass Flow Controller), the corresponding process time step sizes of the deposition step and the etch step can be shortened. Namely, the process time step sizes are shortened cleverly by delaying the response time of the MFC. The delay in response time of the MFC does not affect the process stability, but rather ensures the stability and controllability of the MFC. The process stability is improved. The scallop defect is reduced.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a method for etching a silicon substrate by a Bosch process. Background technique [0002] In the Bosch process, the deposition step (deposition step) and the etching step (etch step) will switch each other, and the switching between the deposition step and the etching step will inevitably produce wrinkles (scallop). As the feature size becomes smaller, the requirements for scallop become more and more stringent. [0003] The industry reduces the generation of scallop by reducing the time step of the deposition step and the etching step. However, in the current bosch process, the time step of the deposition step and the etching step has been shortened to the order of milliseconds (ms). There are also relatively high requirements for each component in the process chamber; especially for the mass flow controller (MFC), because the response speed of the MFC is an important p...

AI Technical Summary

Problems solved by technology

[0003] The industry reduces the generation of scallop by reducing the time step of the deposition step and the etching step. However, in the current bosch process, the time step of the deposition step and the etching step has been shortened to the order of milliseconds (ms). There are also relatively high requirements for each component in the process chamber; especially for the mass flow controller (MFC), because the response speed of the MFC is an important parameter in the design of the bosch process chamber; However, since the MFC controls the gas flow through the valve, in the actual process that needs to switch the MFC quickly, the MFC often has a time delay, resulting in an unsatisfactory MFC response curve.

In order to reduce the response delay of the MFC, it is necessary to adjust the response speed of the MFC to the highest limit, which will reduce the process stability and controllability of the MFC, thereby reducing the process stability of the entire process chamber

Images