Arylmethyl sulfones: A new class of photoacid generators

Abstract

The X‐ray and deep UV radiation response is described for resist systems consisting of poly(4‐tert‐butoxycarbonyloxystyrene‐co‐sulfur dioxide) PTBSS combined with an arylmethyl sulfone. A 2:1 4‐tert‐butoxycarbonyloxystyrene (TBS): sulfur dioxide (SO2) resist has been found to function as a highly sensitive, 1.4 nm X‐ray, single‐component, chemically amplified resist. The same resist, however, exhibits reduced sensitivity to 0.8 nm X‐rays and deep UV (248 nm) radiation. Improvement in 0.8 nm X‐ray sensitivity is achieved by the addition of 12 mol% bis(3,4‐dichlorobenzyl) sulfone (DCBS) to the 2:1 TBS:SO2 resist. For this two‐component resist formulation, the 0.8 nm X‐ray sensitive improved from >375 to 125 mJ/cm2. Similarly, the sensitivity of the 3:1 TBS:SO2 copolymer to deep UV radiation improves to 40 mJ/cm2 with addition of 10 mol% DCBS. Sulfones, such as DCBS, provide two‐component resist formulations capable of <0.5 μm resolution.

Sensitization of polymethacrylate resist with adding acid-generating promoters upon exposure to EUV light

“…It is important to note here that DTS itself did not decompose much by radiolysis to produce acid. Although some sulfone compounds have been reported to decompose and produce sulfinic acid, [37][38][39]40) the decomposition efficiency of diphenyl sulfone is very low (only approximately 1/100 per ionizing event 41) ). The film without the PAG and with 30 wt% DTS added to the polymer did not dissolve in the alkaline developer even when exposed to 150 mJ cm −2 EUV.…”