High Quality RTCVD Sidewall Spacer Dielectrics

Abstract

AbstractRapid thermal chemical vapor deposition (RTCVD) has been investigated as an alternative to low pressure chemical vapor deposition (LPCVD) for formation of sidewall spacer dielectric. Silane (SiH 4 ) and tetraethylorthosilicate (TEOS) were chosen as the silicon gas sources in these studies. Reasonable deposition rates were obtained for RTCVD oxides, oxynitrides and nitrides for use in thin sidewall spacer application. Refractive index and etch rate measurements suggest that oxides deposited with a 2 % flow rate ratio of SiH 4 /N2O and annealed at 900 °C for 10 seconds produces films with excellent structural quality. Refractive index and wet etch rate both exhibit a linear dependence with the gas flow ratio. An increase in deposition pressure decreased the refractive index while increasing the etch rate. Oxide and oxynitride dielectrics formed using SiH 4 had a much superior step coverage over a wide range of aspect ratios than TEOS dielectrics. Dit and breakdown fields for oxides and oxynitrides with 3 atomic % nitrogen were comparable to that of thermal oxide indicating their good electrical quality. The results reported suggest that RTCVD sidewall spacers are a promising candidate for use in future MOSFET devices.