GROWTH-PROCESS OF THIN CHEMICAL-VAPOR DEPOSITION-ALUMINUM FILMS AND ITS UNDERLAYER DEPENDENCE - REAL-TIME MONITORING OF REFLECTED LIGHT-INTENSITY AT THE DEPOSITING SURFACE

It is known that the reflectivity of aluminum (Al) film deposited by c hemical vapor deposition (CVD) decreases with an increase of film thic kness as its surface roughens. A thin, smooth film is effective for fi lling small holes and narrow trenches by conformal deposition, but a r ough surface is not effective. In this study, a real-time monitoring o f the CVD-Al film deposition process has been attempted by measuring t he reflected light intensity at the depositing film surface. By finish ing the deposition when the monitored reflected light intensity of the He-Ne laser reached the maximum, a film with a very smooth surface co uld be reproduced. Furthermore, the lower limitation of smooth continu ous film thickness was compared for four different cases. Investigated underlayers were Ti and TiN deposited by sputtering (SPT). On these u nderlayers, CVD-AI film was deposited without exposure to atmosphere o r with exposure to atmosphere prior to the deposition, resulting in a total of four deposition conditions. The results showed that Al film d eposited on TiN without exposure to atmosphere had the thinnest and th e smoothest continuous film among the four. Since the thickness was 60 nm, the filling of 0.12-mu m diameter holes or 0.12-mu m wide trenche s can be expected by this process.