ROLES OF SURFACE FUNCTIONAL-GROUPS ON TIN AND SIN SUBSTRATES IN RESIST PATTERN DEFORMATIONS

Resist pattern deformations on a bottom anti-reflective layer (BARL) a re a serious problem for deep UV lithography. To clarify the mechanism of these pattern deformations, we analyzed SiN and TiN substrates (ca ndidates of BARL materials) by Auger electron spectroscopy (AES) and t hermal desorption (TDS). We also applied N-2 annealing and thermal oxi dation to the substrates. To examine the reactivity of the substrates to the acid generated in the resist, the potential energy and partial charges of model compounds were calculated using the molecular orbital method. By comparing experimental and calculational results, it was f ound that the Si-OH group neighboring N atoms on SiN substrates was a stronger base than the Si-OH group neighboring O atoms. We also found that NHx, groups can easily react with the acid. The oxidation of SiN, which eliminates NHx and N-Si-OH, prevented pattern deformation. In t he case of TIN, on the other hand, oxidation was not effective because Ti-O-Ti can be decomposed by the acid.