Optical Detection Method for High Aspect Ratio Microstructures

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.

3D microscopy in industrial measurements

“…In the metamaterials, nanophotonic and micromachine fields, to improve the performance of microdevices, special microstructures with depths far beyond the focal depth range of optical diffraction are expected. 76,77 In addition, the transverse line width should remain unchanged or slightly increase with increasing depth. For such microdevices, the aspect ratio (depth-to-width ratio) is the main evaluation parameter that describes the difficulty of its manufacturing and detection.…”

“…However, it requires a vacuum environment and destructive section preparation, being unsuitable to monitor microstructures during fabrication. 77 Compared with the abovementioned measurement methods, optical noncontact measurement is the preferred method. This method for high-aspect-ratio microstructures mainly involves interference microscopy, infrared reflectance spectroscopy, through-focus scanning optical microscopy or similar techniques.…”

“…In the metamaterials, nanophotonic and micromachine fields, to improve the performance of microdevices, special microstructures with depths far beyond the focal depth range of optical diffraction are expected 76,77 . In addition, the transverse line width should remain unchanged or slightly increase with increasing depth.…”

“…In addition, SEM can provide accurate measurements of high‐aspect‐ratio microstructures. However, it requires a vacuum environment and destructive section preparation, being unsuitable to monitor microstructures during fabrication 77 …”