Fluorinated Polymethacrylates as Highly Sensitive Non-chemically Amplified E-beam Resists

Strahan, Jeff R.
Adams, Jacob R.
Jen, Wei-Lun
Vanleenhove, Anja
Neikirk, Colin C.
Rochelle, Timothy
Gronheid, Roel
Willson, C. Grant
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In an effort to improve upon the sensitivity of commercial non-chemically amplified e-beam resists, four polyacrylates functionalized with alpha-CF3 and/or CH2CF3 alkoxy substituents were studied. The alpha-CF3 substituent is known to increase backbone-scission efficiency while simultaneously eliminating acidic out-gassing and cross-linking known to occur in alpha-halogen substituted polyacrylates. Contrast curves for the polymeric alpha-CF3 acrylates, generated through e-beam exposure, showed the resists required an order of magnitude less dose than the current industry-standards, PMMA and ZEP. The fundamental sensitivity of these materials to backbone scissioning was determined via Co-60 gamma-ray irradiation. The chain scissioning, G(s), and cross-linking, G(x), values calculated from the resulting change in molecular weight demonstrated that all fluorinated resists possess higher G(s) values than either PMMA or ZEP and have no detectable G(x) values. Utilizing e-beam and EUV interference lithographies, the photospeed of PMTFMA was found to be 2.8x and 4.0x faster, respectively, than PMMA.

Jeff R. Strahan, Jacob R. Adams, Wei-Lun Jen, Anja Vanleenhove, Colin C. Neikirk, Timothy Rochelle, Roel Gronheid, C. Grant Willson. Advances in Resist Materials and Processing Technology XXVI, 72733G (Apr., 2009); doi: 10.1117/12.813736