Paramjit Jit Singh

US Patent:

61181676, Sep 12, 2000

Filed:

Nov 13, 1997

Appl. No.:

8/969400

Inventors:

Eugene DiSimone - Santa Clara CA
Paramjit Singh - Newark CA

Assignee:

National Semiconductor Corporation - Santa Clara CA

International Classification:

H01L 2176
H04L 2176

US Classification:

257510

Abstract:

A polycrystalline silicon coated nitride-lined shallow trench technique for isolating active regions on an integrated circuit involves reducing the oxide encroachment and the "bird's beak" structure. The technique involves forming an isolation trench, or recess, in the substrate. This recess is then lined with a layer of silicon dioxide layer, and then a layer of silicon nitride. Subsequently, a polycrystalline silicon material is deposited in the recess and is then oxidized to form a field oxide and planarized. Since the recess is nitride-lined, which prevents oxidizing species from reaching the oxide layer beneath the nitride layer, and the polycrystalline silicon is oxidized, the result is zero oxide encroachment resulting in the elimination of the "bird's beak" structure.

US Patent:

59769505, Nov 2, 1999

Filed:

Jul 21, 1998

Appl. No.:

9/119865

Inventors:

Eugene DiSimone - Santa Clara CA
Paramjit Singh - Newark CA

Assignee:

National Semiconductor Corporation - Santa Clara CA

International Classification:

H01L 2176

US Classification:

438432

Abstract:

A side wall masked isolation (SWAMI) technique for isolating active regions on an integrated circuit involves reducing the "bird's beak" structure. The technique involves forming an isolation recess in the substrate, and then lining the recess with a layer of silicon dioxide, and then a layer of silicon nitride. Then, oxide spacers are formed on each of the sidewalls of the recess. The recess is then anisotropically etched until the substrate at the bottom of the recess is exposed. This etch process involves removing portion of both the silicon dioxide and the silicon nitride layers formed at the bottom of the recess. Subsequently, a layer of polycrystalline silicon material is deposited in the recess and is then etched back and oxidized to form a field oxide. Since the polycrystalline silicon is oxidized, the result is negligible oxide encroachment resulting in a reduction in the "bird's beak" structure.