Photo-electron chemistry of photoresist outgassing upon DUV, VUV, EUV, and BEUV irradiation

Study of electron-induced chemical transformations in model resists

“…Identifying outgassed compounds is also possible by assuming ideal fragmentation locations as shown in Figure 1. 5 Outgassing from tBMA consisted primarily of isobutylene (m/z=15, 26-29, 37-42, 50-57) and CO2 (m/z=12, 16, 28, 44). A previously observed 4,5,9 but unexplained peak from a similar polymer system at m/z=43 also shows clear signal and may correspond to side-reactions creating acetone or propane volatiles.…”

“…5 Outgassing from tBMA consisted primarily of isobutylene (m/z=15, 26-29, 37-42, 50-57) and CO2 (m/z=12, 16, 28, 44). A previously observed 4,5,9 but unexplained peak from a similar polymer system at m/z=43 also shows clear signal and may correspond to side-reactions creating acetone or propane volatiles. Outgassing from PMMA can be attributed primarily to CH4 (m/z=15-16), methyl alcohol-CH3OH (m/z=15, 28-32), and CO2 (m/z=12, 16, 28, 44).…”

“…1 Studies have identified many reactions occurring in polymer materials exposed to EUV, such as main-chain and side-chain scission of polymers, 2 direct deprotection, and cross linking. 3,4 A comprehensive study by Ho et al 5 was able to quantify the relative amounts of each of these reactions induced by EUV exposure for two common polymers in CAR material systems. The picture becomes even more complex in full CAR systems as the ability of PAG materials to absorb EUV radiation and react with electrons leads to the enhancement of deprotection reactions.…”