Advantages of thick CVD gate oxide for trench MOS gate structures

We have done research for the purpose of improving the reliability of trench MOS gate devices that utilize trench gate oxide over 10 nm in thickness. This paper reports, for the first time, that the CVD gate oxide (CGO) film is much more effective as a gate dielectric for use in trench MOS gate devices than the thermal oxide widely used in the SiO/sub 2/ gate dielectric of MOS gate devices. Our results show that the electrical characteristics (leakage characteristic and Time-Zero Dielectric Breakdown characteristic), the reliability and current drivability of trench MOS gate devices can be dramatically improved by CVD gate oxide (especially oxynitride CGO). These improvements are caused by the excellent uniformity of thickness and the good quality of gate oxide which formed on an inner trench with the specific geometrical factor. From the viewpoint of insuring the reliability for large trench capacitor area, this new CGO dielectric is a promising candidate for trench MOS gate power devices.