公开(公告)号：US20210005725A1

公开(公告)日：2021-01-07

申请号：US16868143

申请日：2020-05-06

Applicant: Silicon Storage Technology, Inc.

Inventor： Leo XING ,  Chunming WANG ,  Guo Yong LIU ,  Melvin DIAO ,  Xian LIU ,  Nhan DO

IPC: H01L21/28 ,  H01L27/11521 ,  H01L27/11531 ,  H01L29/423 ,  H01L29/788 ,  H01L29/66 ,  H01L21/02 ,  H01L21/3213 ,  H01L21/265

Abstract: A method of forming a memory device includes forming a second insulation layer on a first conductive layer formed on a first insulation layer formed on semiconductor substrate. A trench is formed into the second insulation layer extending down and exposing a portion of the first conductive layer, which is etched or oxidized to have a concave upper surface. Two insulation spacers are formed along sidewalls of the trench, having inner surfaces facing each other and outer surfaces facing away from each other. A source region is formed in the substrate between the insulation spacers. The second insulation layer and portions of the first conductive layer are removed to form floating gates under the insulation spacers. A third insulation layer is formed on side surfaces of the floating gates. Two conductive spacers are formed along the outer surfaces. Drain regions are formed in the substrate adjacent the conductive spacers.