Low-pressure rapid thermal chemical vapor deposition of oxynitride gate dielectrics for n-channel and p-channel MOSFETs

The properties of oxynitride gate dielectrics formed using a low-pressure, rapid thermal chemical vapor deposition (RTCVD) process with SiH/sub 4/, NH/sub 3/, and N/sub 2/O as the reactive gases are presented. Material analyses show an increase of uniform nitrogen and interfacial hydrogen content with increasing NH/sub 3//N/sub 2/O flow rate ratio. MOS capacitors with both n-type and p-type substrates and both n-channel and p-channel MOSFETs were analyzed electrically. The results show increasing fixed oxide charge and interface state density with increasing nitrogen and hydrogen content in the film. A decrease in peak transconductance and improved high-field transconductance was observed for n-channel MOSFETs. Improved resistance to hot-carrier interface state generation was also observed with increasing nitrogen concentration in the films. The results suggest that an optimal nitrogen concentration of approximately 3 at.% can be considered for further development of this technology.