SURFACE-ROUGHNESS OF SIO2 FROM A REMOTE MICROWAVE PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION PROCESS

We have investigated the roughness of the top surface of silicon dioxi de deposited via a remote plasma enhanced chemical vapor deposition (R PECVD) process in a microwave reactor. We find a roughening transition at a deposition temperature of approximately 250 degrees C. Above thi s temperature, the surface is fairly smooth (root mean square roughnes s similar to 0.3 nm). Below this deposition temperature, the oxide sur face becomes extremely rough. Rapid thermal annealing at 900 degrees C does not eliminate this roughness, which is very nonuniform at the na nometer scale. For very thin RPECVD oxide applications, oxide surface roughness could be a limitation. We have used our three-dimensional Po isson solver in order to investigate the effects of oxide surface roug hness taken from actual atomic force microscopy measurements on the co nfining potential within the silicon inversion layer of a metal-oxide- semiconductor (MOS) field effect transistor. In order to assess the qu ality of our process and system, oxides are characterized electrically with MOS capacitors, and structurally with Fourier transform infrared spectroscopy, high-resolution cross-sectional transmission electron m icroscopy, and etch rates in HF containing solutions. (C) 1998 America n Vacuum Society.