A method of forming a multi-layered dual-polysilicon structure

摘要

First and second trenches of differing depths are formed in a first insulating layer (12), a second insulating layer and polysilicon material then being formed. Part of the polysilicon is removed and an implantation barrier (40) is formed. Forming a multilayer semiconductor structure (50) comprises: (i) forming two trenches of different depths in the first insulating layer (12); (ii) forming the second insulating layer in the trenches; (iii) forming polysilicon material in the trenches so they are substantially filled; (iv) removing a portion of the polysilicon so the top surface (18) of the first insulating layer is not coplanar with a top surface of the polysilicon remaining in the trenches; (v) forming an implantation barrier (40) in the trenches; and (vi) processing the implantation barrier in the trenches so its top surface (42) is coplanar with the top surface of the first insulating layer. An independent claim is also included for: the multilayered semiconductor structure comprising the layers described on a substrate.