Low-temperature formation of thin-gate SiO2 films by the ultrahigh-vacuum chemical vapor deposition with reduced subcutaneous oxidation using remote-plasma-activated oxygen and Si2H6

We have investigated the growth condition dependence on the properties of S iO2 films by remote-plasma-enhanced chemical vapor deposition (RPECVD) in a n ultrahigh vacuum system with remote-plasma-activated oxygen and Si2H6. Du ring the RPECVD, subcutaneous oxidation of the Si substrate was not negligi ble, which degraded the controllability of the film thickness and the elect rical properties. The amount of the active oxygen species that dominates th e reactions of subcutaneous oxidation was considered to be significantly re duced with increasing O-2 flow rate, while that of "pure" CVD remained unch anged. As a result, precise control of the RPECVD SiO2 thickness with reduc ed subcutaneous oxidation has been achieved by setting the O-2 flow rate to the maximum and by using higher Si2H6 flow rates. The characteristics of t he SiO2 films obtained using optimized RPECVD conditions at temperatures lo wer than 600 degreesC without a postannealing process have been demonstrate d to be comparable to those of thermally grown films.