Conformity optimization for metal interconnections in MOS technologies

Abstract

Presented study was focus on optimization of planarization and metal conformity on steps in MOS technology. The experiment regards a three fold problem: the structure of the planarization silicon dioxide thin film in order to optimized the slope of the contact windows, the metal used and the conformity of metal interconnections. We studied the profiles of contact windows configured in several composed silicon dioxide films (thermal SiO/sub 2/ and APCVD SiO/sub 2/) using /spl alpha/-step measurements. Then, after metal deposition and configuration we observed by SEM investigations the conformity of metal films on steps (contact, cracking, thinning on edge of the window). Finally, we proposed a sequence of composed planarization film (thermal SiO/sub 2/ and APCVD SiO/sub 2/ undoped and phosphorous doped) and metallization proved by /spl alpha/-step, SEM and functional investigations to be an optimized solution.