Abstract
In order to understand the surface roughening mechanism during the chemical vapor deposition of aluminum (Al-CVD), the authors investigated the effect of underlayers on the nucleation, coalescence and surface roughening of Al film using in situ surface reflectivity measurement. The maximum reflectivity corresponded to the Al nuclei coalescence for the TiN and Cu underlayers, while the reflectivity decreased almost continuously for the Si, Ta and TaN. Surface observation of the initial growth revealed that a high Al nucleation density is necessary for fabrication of smooth Al films. Crystallographic orientation of Al film was observed at the characteristic points of the reflectivity behavior. Film orientation showed different trends for the TiN and Cu underlayers, corresponding to the difference in the reflectivity behavior. The existence of second nucleation of Al on continuous Al films is suggested to be the cause of surface roughening.