The continuous studies for both the outgassing reduction and the sensitivity improvement by applying low outgassing photo acid generator with a various kinds of polymer protection group were discussed in this paper. Further reduction of the outgassing segments from the resist was demonstrated to achieve the total outgassing amount below the detection limit of GC-MS (ca. less than 1X10¹⁰ molecules / cm²). Loading a large sized acetal group could be successfully reduced the amount of the outgassing segments from polymer below the tool detection limit, which would be acceptable for a high volume manufacturing tool usage. The development properties of poly(hydroxyl styrene) (PHS) based bulky acetal polymers were measured by changing molecular weight. The high dissolution rate contrast was obtained with the bulky acetel protected low molecular weight polymer. A resolution capability study was carried out with micro exposure tool (MET) at LBNL and Albany. The correlation between LWR through CD and DOF was measured by loading various amounts of quencher. The resolution capability of newly developed EUV resist had been successfully improved by modifying both resist polymer matrix and quencher amount optimization. It was possible to obtain 27.7nm lines with MET tool, where LWR value at 35 nm L/S was 3.9 nm with reasonable sensitivity range.