S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Mechanical Aerospace Engineering (기계항공공학부) Theses (Master's Degree_기계항공공학부)
Development of Tomographic Imaging and Fitting Methods for Critical Dimension Measurement of TFT-LCD
Tomographic Imaging과 Fitting 기법을 이용한 TFT-LCD의 Critical Dimension 측정에 대한 연구
- 공과대학 기계항공공학부
- Issue Date
- 서울대학교 대학원
- Critical Dimension; TFT-LCD; Micro Pattern; Fitting Method; Tomographic Imaging; White-light Phase Shifting Interferometer
- 학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2016. 2. 박희재.
- In this paper, two methods are introduced to enhance the repeatability of critical dimension measurement on certain micro pattern by using White-light Phase Shifting Interferometry (WLPSI). Since WLPSI collects the coherence signal by vertically scanning the sample, the repeatability of WLPSI is often affected by external noise like mechanical vibrations. The external interference to the machine causes numerical error on the measured data. Profile Fitting method is introduced to enhance the repeatability. The fitting parameters are calculated by using iterative non-linear fitting process, Levenberg-Marquarts nonlinear fitting algorithm. Once the fitting parameters are determined, the sampled cross sectioned profile of the mirco-pattern can be interpolated smoothly by fitting process which eventually eliminate possible error factors at the source data. During the Profile Fitting method, the critical dimension data from tomographic image is utilized. Based on the reason, the repeatability of tomographic CD measurement should be stable to achieve for better repeatability. Gaussian Fitting method is suggested for the tomographic image acquisition process to eliminate possible noise properties on the modulus function. In order to evaluate the performance of suggested methods, multiple measurements of pattern samples are conducted.