Precise CD Measurement of Micro Grating Iinewidth Using Multi-view AFM Stitching Method

CSME 2023/03
Volume 44 No.1 : 23-36

Precise CD Measurement of Micro Grating Iinewidth Using Multi-view AFM Stitching Method

Liang-Chia Chen^a, Nguyen Van Thai^a and Bo-Ching He^b
^aDepartment of Mechanical Engineering, National Taiwan University, , No.1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan, R.O.C
^bCenter of Measurement Standards, Industrial Technology Research Institute, Hsinchu 30011, Taiwan, R.O.C

Abstract: This article presents a new critical dimension (CD) measuring method for nanoscale linewidth measurement of micro gratings employing an image stitching algorithm with AFM (atomic force micro-scope) multi-view scans. Due to the geometric con-straints of AFM scanning, it has been considered a challenging and erroneous task to measure and recon-struct a micro grating using AFM since the AFM measuring tip in the scanning process cannot keep its measuring orientation well against both right-angle side walls of a grating simultaneously. To resolve this, a new strategy of using multi-view scanning with an image stitching algorithm for precise data fusion is presented. Some measurement experiments were conducted to verify the feasibility of the development. As confirmed by measured data, the measurement bias in measuring micro grating using AFM can be controlled at less than 1.0 nanometer for a grating with a linewidth of 820.1nm.

Keywords: critical dimension (CD); image registration; linewidth measurement; atomic force microscopy (AFM); image stitching.

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