Two step process for forming void-free oxide layer over stepped surface of semiconductor wafer

A two step process for forming a silicon oxide layer over a stepped surface of a semiconductor wafer while inhibiting the formation of voids in the oxide layer which comprises:

• a) depositing a void-free first layer of an oxide of silicon over said stepped surface of said semiconductor wafer in a CVD chamber by flowing into said chamber a gaseous mixture comprising a source of oxygen, at least a portion of which comprises O.sub.3, and tetraethylorthosilicate as the gaseous source of silicon, while maintaining the pressure in said CVD chamber within a range of from about 500 Torr to about 760 Torr to form said void-free oxide layer;
• and
• b) depositing a second layer of oxide over said void-free first oxide layer in a CVD chamber by flowing into said chamber a gaseous mixture comprising a source of oxygen, at least a portion of which comprises O.sub.3, and tetraethylorthosilicate as the gaseous source of silicon, while maintaining said CVD chamber at a pressure within a range of from about 40 Torr to about 100 Torr.

A two step process for forming a silicon oxide layer over a stepped surface of a semiconductor wafer which will form void-free oxide in low regions between raised portions of the wafer which comprises:

• a) depositing silicon oxide over said stepped surface of said semiconductor wafer in a CVD chamber by flowing into said chamber a gaseous mixture comprising a source of oxygen and tetraethylorthosilicate as the gaseous source of silicon, while maintaining the pressure in said CVD chamber within a range of from about 250 Torr to about 760 Torr until said low regions on said stepped surface between said raised portions of said surface are filled with oxide up to at least the original level of said raised portions of said stepped surface prior to said deposition, to form said void-free oxide;
• and
• b) depositing further oxide over said void-free oxide on said wafer in said CVD chamber by flowing into said chamber a gaseous mixture comprising a source of oxygen and tetraethylorthosilicate as the gaseous source of silicon, while maintaining said CVD chamber at a pressure below 250 Torr.