Understanding of protective deposition layer density for TEM sample preparation on Photoresist at cryogenic temperatures
Understanding of protective deposition layer density for TEM sample preparation on Photoresist at cryogenic temperatures
Monday, November 17, 2025: 10:40 AM
1 (Pasadena Convention Center)
Summary:
Photoresist (PR) profile analysis is essential in the semiconductor industry, as abnormal PR profiles and defects can significantly affect subsequent processes and overall device performance. To address this challenge, our previous work introduced a fully cryogenic workflow using cryo-FIB and cryo-TEM to minimize thermal damage during both sample preparation and analysis. Although significantly improved the height and CD of PR by cryo-FIB and cryo-TEM analysis compared to room-temperature analysis, further optimization is expected to reduce shrinkage, particularly in enhancing the protective layer against ion beam exposure in the cryogenic TEM sample preparation process. In this study, we investigate the effect of the protective layer on preserving original PR profiles during cryo-FIB preparation. Platinum (Pt) can be used as the protective material during cryo-FIB preparation. To enhance its effectiveness, we examine several approaches such as temperature optimization during deposition, a beam exposure technique and deposition direction alternation during cryogenic deposition. We propose the correlations between preserving original PR profiles and the deposition temperature, beam exposures and deposition direction. Our findings reveal that optimizing these parameters enhances deposition density and reduces shrinkage, resulting in cryo-TEM measurements that more accurately reflect the reference PR thickness.
Photoresist (PR) profile analysis is essential in the semiconductor industry, as abnormal PR profiles and defects can significantly affect subsequent processes and overall device performance. To address this challenge, our previous work introduced a fully cryogenic workflow using cryo-FIB and cryo-TEM to minimize thermal damage during both sample preparation and analysis. Although significantly improved the height and CD of PR by cryo-FIB and cryo-TEM analysis compared to room-temperature analysis, further optimization is expected to reduce shrinkage, particularly in enhancing the protective layer against ion beam exposure in the cryogenic TEM sample preparation process. In this study, we investigate the effect of the protective layer on preserving original PR profiles during cryo-FIB preparation. Platinum (Pt) can be used as the protective material during cryo-FIB preparation. To enhance its effectiveness, we examine several approaches such as temperature optimization during deposition, a beam exposure technique and deposition direction alternation during cryogenic deposition. We propose the correlations between preserving original PR profiles and the deposition temperature, beam exposures and deposition direction. Our findings reveal that optimizing these parameters enhances deposition density and reduces shrinkage, resulting in cryo-TEM measurements that more accurately reflect the reference PR thickness.