Method for detecting roughness of etched side walls through capacitance changes

Abstract

The invention discloses a method for detecting roughness of etched side walls through capacitance changes. The technical process is added before the etching process is carried out on a functional area only, and design complexity of functional devices is prevented from being increased. The roughness of the side walls of the functional area is reflected through the capacitance changes of detection areas, errors caused by small sizes are reduced, operations such as fracture surfaces causing damage to the devices are avoided, and nondestructive detection on etched structures is achieved. The number of the detection areas is determined through sizes and varieties of etched windows of the functional area, the purpose of more accurately detecting the roughness of the etched side walls under different conditions is achieved, and meanwhile the roughness of the etched side walls under the different etching conditions can be detected in one step. The technical process is simple, mature technologies are adopted in the process, technical difficulty is low, implementation is easy and convenient, and operation is easy.

Description

technical field [0001] The invention belongs to the field of micro-electro-mechanical system (MEMS) processing technology, and is particularly applied to the plasma etching technology in the etching process. By designing an independent detection area, the capacitance measurement of the detection structure is used to reflect the roughness of the side wall in the etching process. Background technique [0002] The etching process is a very important single process in the MEMS processing technology, and an indispensable technical means to realize the functional structure of the micro-electro-mechanical system. The etching process in the current MEMS processing technology is mainly divided into isotropic etching and anisotropic etching. Isotropic etching is mainly used in large-size, spherical structures that do not have high requirements for body-to-width ratios, and sidewall roughness generally has little impact on such devices. Anisotropic etching is mainly used in deep groov...

AI Technical Summary

Problems solved by technology

Due to the complexity of the plasma model and the etching reaction model, it is theoretically impossible to accurately predict the specific roughness of the sidewall under different etching conditions. At the same time, it is difficult to monitor the etching in real time because the etching process takes place in the closed cavity of the equipment. Variations in sidewall roughness during

[0003] Previous studies often focused on the verticality of the sidewall of the etched deep groove and the roughness of the bottom surface of the deep groove, and the roughness of the sidewall was often neglected. The inspection was generally carried out by observing the cross-section of the device structure with an electron microscope, and estimating the roughness by using electron microscope photos. , this method can be applied to structures with large size and low aspect ratio, but for structures with small size and high aspect ratio, the acquisition of the cross section is easy to destroy the functional structure, and it is easy to cause non-etched sidewall roughness , and as the complexity of the device structure increases, there will be different etching windows on the same silicon wafer, and the sidewall roughness of a section cannot reflect the sidewall roughness formed under other etching conditions. It cannot directly reflect the influence of sidewall roughness on the electrical performance of the device

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