Actinic imaging and evaluation of phase structures on EUV lithography masks
The authors describe the implementation of a phase-retrieval algorithm to reconstruct phase and complex amplitude of structures on EUV lithography masks. Many native defects commonly found on EUV reticles are difficult to detect and review accurately because they have a strong phase component. Understanding the complex amplitude of mask features is essential for predictive modeling of defect printability and defect repair. Besides printing in a stepper, the most accurate way to characterize such defects is with actinic inspection, performed at the design, EUV wavelength. Phase defect and phase structures show a distinct through-focus behavior that enables qualitative evaluation of the object phase from two or more high-resolution intensity measurements. For the first time, phase of structures and defects on EUV masks were quantitatively reconstructed based on aerial image measurements, using a modified version of a phase-retrieval algorithm developed to test optical phase shifting reticles.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- Materials Sciences Division
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 1004158
- Report Number(s):
- LBNL-4150E; TRN: US201103%%378
- Journal Information:
- JVST B, Vol. 28, Issue 6; ISSN 1071-1023
- Country of Publication:
- United States
- Language:
- English
Similar Records
Actinic EUV mask inspection beyond 0.25 NA
Actinic Mask Inspection at the ALS Initial Design Review