A comparative evaluation of spin-on-glass cure by FTIR technique

Planarization techniques requires a deeper understanding of spin-on-glass (SOG) material behaviour. Besides chemical properties, the cure processes are becoming more and more relevant to achieve a positive impact over microelectronic devices manufacturing flow. In this paper we present a comparative evaluation of different thermal and plasma SOG treatments as detectable by FTIR technique. As far as the vacuum cure is concerned, we found 425‡ C at 300 mTorr a suitable process window. In order to investigate the plasma cure effect on SOG materials we used N2 plasma connected to either a radio frequency or microwave power generator. We found these plasmas not effective in SOG curing. The O2 plasma, in a barrel type reactor connected to a radio frequency generator, resulted in both an effective material shrinkage by an ashing reaction, and C elimination by an oxydation reaction. These results, together with the non cumulative effects of plasma and the vacuum cure, represent the more relevant conclusions of our investigation. Thus, the simple vacuum cure process has been found the most suitable for microelectronics manufacturing applications.