Patent ID: 6337255
Filing Date: 2002-01-08
Classification: H01L,Y10S

Abstract:
A method for forming a trench structure in a silicon substrate, the trench structure electrically insulating a first region of the silicon substrate from a second region of the silicon substrate, the method which comprises:growing a thermal oxide layer on a surface of the silicon substrate; applying and patterning a mask layer over the thermal oxide layer resulting in a patterned mask layer; etching a trench using the patterned mask layer down to a predetermined depth into the silicon substrate; depositing a substantially conformal covering oxide layer with a substantially uniform thickness that is sufficient for completely filling the trench; depositing a polysilicon layer on the conformal covering oxide layer, a thickness of the polysilicon layer corresponding at least the predetermined depth of the trench; chemical mechanical polishing of the polysilicon layer as far as a level of a surface of the conformal covering oxide layer with high selectivity between a polysilicon material of the polysilicon layer and an oxide material of the conformal covering oxide layer; and substantially nonselective, joint etching of the polysilicon material of the polysilicon layer and of the oxide material of the covering oxide layer while maintaining a planar surface produced in accordance with the chemical mechanical polishing step, the substantially nonselective etching step being carried out at least until all the polysilicon material of the polysilicon layer being removed in a region of the trench.