Optical Detection Method for High Aspect Ratio Microstructures.

Wenbin Wei,Yue Hu,Ying Xiong,Lijuan Chen,Zhao Wu,Yi Wang,Shuangyue Hou,Yangchao Tian,Gang Liu

doi:10.3390/mi11030296

Abstract

High aspect ratio microstructures (HARMS) are of great importance for many application fields. Many defects are generated during the fabrication processes, especially in line microstructures, and it is necessary to examine the quality of the structures after each process. However, there is no suitable efficient nondestructive detection method to monitor microstructures during the fabrication processes. In this paper, an optical detection method capable of detecting the structures by analyzing the reflection of light on the line HARMS is proposed. According to the image of reflected visible light, this method can determine whether there are defects in structures, so as to realize efficient detection. Preliminary simulations and experiments have been performed to confirm the feasibility and validity of the proposed method for detecting line microstructures. This method is expected to obtain more information about microstructures by further optimizing system parameters.

Highlights

High aspect ratio microstructures (HARMS) are widely used in many fields, such as optics [1,2,3] and MEMS (Microelectromechanical systems) [4,5,6,7,8]
It can be seen that thereimages, is only aand slight the tilted andkinds normal normal structure in the optical microscopic it isdifference difficult between to determine which of structure in the optical microscopic images, and it is difficult to determine which kinds of defects exist defects exist in the microstructures
They are quite different in the optical detection in the microstructures

Summary

Introduction

High aspect ratio microstructures (HARMS) are widely used in many fields, such as optics [1,2,3] and MEMS (Microelectromechanical systems) [4,5,6,7,8]. During the UV lithography, development and electroplating processes, owing to the diffraction effect and the limitations of the mechanical strength of photoresist, the pattern is deformed, such as trapezium, distortion, tilt, and collapse [13,14,15]. These deformations could influence the performance of microstructures. Height, linewidth and the shape of the sidewall of the microstructure need to be detected. For HARMS, the shape of the sidewall is the most important feature to characterize the quality of the structure. The slight deformation of the sidewalls can have a great influence on HARMS, and the detection of the sidewalls is of great significance

Methods

Results

Conclusion