Effect of underlayers on the morphology and orientation of aluminum films prepared by chemical vapor deposition using dimethylaluminumhydride

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 him using in situ surface reflectivity measurement. The maximum reflectivi ty corresponded to the Al nuclei coalescence for the TiN and Cu underlayers , while the reflectivity decreased almost continuously for the Si, Ta and T aN. Surface observation of the initial growth revealed that a high Al nucle ation density is necessary for fabrication of smooth Al films. Crystallogra phic orientation of Al film was observed at the characteristic points of th e reflectivity behavior. Film orientation showed different trends for the T iN and Cu underlayers, corresponding to the difference in the reflectivity behavior. The existence of second nucleation of Al on continuous Al films i s suggested to be the cause of surface roughening.