US Patent 7118971 Method for fabricating trench power device

Embodiments of the invention relate to a fabrication method of an electronic device, more particularly to a fabrication method of a power device in which an oxide layer at the bottom of the trench is provided to reduce Miller capacitance and further reduce RC delay. In one embodiment, a method for forming an oxide layer at the bottom of a trench comprises providing a first substrate with at least one trench therein; forming a first oxide layer on the bottom and sidewalls of the trench; removing the first oxide layer at the bottom of the trench; and forming a second oxide layer at the bottom of the trench.