Isotopic Labeling Studies of EUV Photoresists Containing Antimony

Abstract

We have investigated the mechanism of photodecomposition of antimony carboxylate complexes of the type Ph 3 Sb(O 2 CR′) 2 by means of EUV outgassing in combination with isotopic labeling. When exposed to EUV light, these compounds decompose to form CO 2 , benzene and phenol. The source of hydrogen needed to create phenol can be traced to hydrogens originating in the original organometallic complex. However, it is much more difficult to trace the origin of the hydrogen needed to convert the phenyl groups to benzene (Ph-H). We propose that the primary source of hydrogen to create benzene is external to the film. Additionally, we have prepared isotopically-labeled versions of Ph3Sb(O2CCH(CH3)2)2 in which the hydrogens in the isobutyrate ligand were replaced with 0, 1, 6 and 7 deuteriums, to provide information about the relative reactivity of these protons during EUV exposure as analyzed by mass spectrometry. High reaction selectivity was identified within the carboxylate dictated by hydrogen location relative to the carbonyl for both benzene and phenol generation. Lastly, the results of these studies were used to propose a series of reaction pathways to generate the aforementioned reaction byproducts.

EUV Photochemistry of α-Substituted Antimony Carboxylate Complexes

“…Prior EUV outgassing studies examined the production of dominant volatile species within a series of alkyl and aryl triphenylantimonydicarboxylate resists. The generation of CO2, benzene and phenol were found to correlate with antimony-carboxylate bond strength [16]. In the present study, we re-examine the in-situ mass spectra of several triphenyl-antimonycarboxylate resists to investigate carboxylate decomposition pathways.…”

“…Deoxygenation and αcleavage reaction pathways can lead to crosslinked antimony-oxide networks, as determined by ToF-SIMS [16]. Previous studies of the d0 and d2 derivatives of triphenylantimonybis(isobutyrate) (MM-49 and d2-MM-49, respectively) provide a good background for understanding these three bond-cleavage reactions [16]. This compound yields dimethylketene (1) and acylium ion (2) upon exposure to EUV (Figure 8).…”

“…Exposure of JP-18 (R = CH3) to EUV light yields CO2, benzene and phenol. Exposure of d6-JP-18 (R = CD3) to EUV light yields CO2, and greater than 95% isotopically pure d0-benzene and d1-phenol [16].…”

“…Bond 3: cleavage of the bond α to the carbonyl yielding an unstable intermediate that can form a ketene through cleavage of the oxygen-carbonyl bond. Deoxygenation and αcleavage reaction pathways can lead to crosslinked antimony-oxide networks, as determined by ToF-SIMS [16]. Previous studies of the d0 and d2 derivatives of triphenylantimonybis(isobutyrate) (MM-49 and d2-MM-49, respectively) provide a good background for understanding these three bond-cleavage reactions [16].…”