Rigorous calibration of negative-tone and positive-tone development of novel EUV chemically amplified resist for performance characterization

Improving the performance of EUV photoresists requires deploying novel approaches in both high energy photoelectron interactions as well as development chemistry. In DUV chemically amplified photoresists, negative tone development can improve performance in certain applications, exploiting better optical contrast of light field masks. For EUV chemically amplified resists, we apply negative tone development with the novel organic developer by Fujifilm to reduce resist swelling while improving patterning performance. We use the PROLITH™ simulation engine to model the photoelectron interactions, resist swelling during negative tone development, and post-exposure bake shrinkage effects. We then analyze the performance improvements of the NTD EUV resist. The PROLITH resist swelling model accurately describes the resist swelling behavior in both negative and positive tone patterning, for both continuum and stochastic simulations. To calibrate the photoresist, we collect focus-exposure matrix wafer Critical Dimensions (CD) and Line-Edge Roughness (LER) measurements using both negative tone and positive tone developers at dense, semi-dense and isolated pitches, contrast curves for both positive and negative tone developers, PEB shrinkage curves, and resist cross sections SEMs for profile characterization. From this data we calibrate the PROLITH advanced chemically amplified photoresist parameters to accurately reproduce the CD behavior through pitch, sidewall profile, and contrast curve characteristics such as clearing dose. The same calibrated resist is enabled in both positive and negative tone versions, with difference only in developer-relevant values. Using the calibrated resist model, we finally use PROLITH to predict the improvement in Depth of Focus and Exposure Latitude of EUV patterning using the NTD photoresist, compared with PTD CAR EUV resists models.