Abstract: A MOSFET with a 0.7˜2.0 micrometers deep trench is formed by first carrying out a processing step of opening a trench in a semiconductor substrate. A thick insulator layer is then deposited in the trench such that the film at the bottom of the trench is much thicker than the sidewall of the trench. The insulator layer at the sidewall is then removed followed by the creation of composite dual layers that form the Gate Oxide. Another embodiment has the insulator layer deposited after Gate Oxide growth and stop at a thin Nitride layer which serves as stop layer during insulator pullback at trench sidewall and during Polysilicon CMP. Embodiments of the present invention eliminates weak spot at trench bottom corner encountered when Gate Oxide is grown in a 0.2 micrometers deep trench with thick bottom oxide.
Type:
Grant
Filed:
May 12, 2005
Date of Patent:
February 14, 2012
Assignee:
M-Mos Sdn.Bhd
Inventors:
Fwu-Iuan Hshieh, Yee Ai Fai, Ng Yeow Keong