US 6,150,235 A · Method of forming shallow trench isolation structures

Abstract

A method for forming shallow trench isolation (STI) structures on a semiconductor substrate is disclosed. First a semiconductor substrate with a first area and a second area adjacent to the first area is provided. A mask layer is formed on the substrate, and is etched to expose portions of the substrate. A first photoresist is formed to cover the second area for exposing the first area. A first implanting procedure is performed with a titled angle to form first doping areas on the substrate encroaching into portions of the substrate covered by the first photoresist. The first photoresist is removed. A second photoresist is formed on the substrate to cover the first area for exposing the second area. And a second implanting procedure is done with a titled angle to form second doping areas on the substrate encroaching into portions of the substrate covered by the second photoresist. The second photoresist is removed. The substrate is etched to remove the first doping areas and the second doping areas for forming trench structures therein. It is noted that portions of the first doping areas and the second doping areas are residual in upper portions of sidewalls of the trench structures adjacent to the mask layer. Then the shallow trench isolations are formed in the trench structures.

Claims16

Dependent claims

A method for forming shallow trench isolation (STI) structures on a semiconductor substrate, said method comprises:

providing a semiconductor substrate, wherein said substrate has a first area and a second area adjacent to said first area;
forming a mask layer on said substrate;
etching said mask layer to expose portions of top surface of said substrate in said first area and in said second area;
forming a first photoresist on said substrate to cover said second area for exposing said first area;
performing a first ion-implanting procedure with a tilted angle to form first doping areas on said substrate by using said first photoresist as a mask, wherein said first doping areas encroach into portions of said substrate covered by said first photoresist;
removing said first photoresist;
forming a second photoresist on said substrate to cover said first area for exposing said second area;
performing a second ion-implanting procedure with a tilted angle to form second doping areas on said substrate by using said second photoresist as a mask, wherein said second doping areas encroach into portions of said substrate covered by said second photoresist;
removing said second photoresist;
etching said substrate by using said mask layer as an etching mask to remove said first doping areas and said second doping areas to form trench structures in said substrate, wherein portions of said first doping areas and said second doping areas are residual in upper portions of sidewalls of said trench structures adjacent to said mask layer;
and
forming shallow trench isolations in said trench structures.

9 more elements

A method for forming shallow trench isolation (STI) structures on a semiconductor substrate, said method comprises:

providing a substrate, wherein said substrate has a PMOS area and a NMOS area adjacent to said PMOS area, wherein said PMOS area is where PMOS devices will be built and said NMOS area is where NMOS devices will be built;
forming a nitride layer on said substrate to cover said PMOS area and said NMOS area;
form a oxide layer on said nitride layer;
etching said oxide layer and said nitride layer to form openings in said oxide layer and said nitride layer to expose portions of said substrate in said PMOS area and said NMOS area;
forming a first photoresist on said substrate and said oxide layer to cover said NMOS area for exposing said PMOS area;
performing a first ion-implanting procedure with a tilted angle to form N-type doping areas in said PMOS areas on said substrate by using said first photoresist as a mask, wherein said N-type doping areas encroach into portions of said substrate covered by said first photoresist;
removing said first photoresist;
forming a second photoresist on said substrate and said oxide layer to cover said PMOS area for exposing said NMOS area;
performing a second ion-implanting procedure with a tilted angle to form P-type doping areas in said NMOS area on said substrate by using said second photoresist as a mask, wherein said P-type doping areas encroach into portions of said substrate covered by said second photoresist;
removing said second photoresist;
etching said substrate by using said oxide layer as an etching mask to remove said N-type doping areas and said P-type doping areas to form trench structures in said PMOS area and said NMOS area of said substrate, wherein residual N-type doping areas are reserved in upper portions of sidewalls of said trench structures in said PMOS area, and residual P-type doping areas are reserved in upper portions of sidewalls of said trench structures in said NMOS area;
and
forming shallow trench isolations in said trench structures.

10 more elements

Dependencies are inferred from the claim text.

Method of forming shallow trench isolation structures

Life of this patent

Method of forming shallow trench isolation structures

Life of this patent

Abstract

Claims16