US 6,306,772 B1 · Deep trench bottle-shaped etching using Cl2 gas

Abstract

A method to fabricate bottle-shaped deep trench into a semiconductor substrate. After a neck profile is formed, the chlorine gas at a predetermined flow rate is added to the etching plasma gas composition, while the flow rates of the plasma gases are increased by about 30% by volume, to create an enlarged lower portion of the deep trench. Preferably, the neck portion is etched using an etching composition which contains HBr, NF3, and (He/O2) provided at flow rates of about 87:13:35 sccm. The enlarged lower portion is etched using an etching composition which contains HBr, NF3, and (He/O2) provided at flow rates of about 113±12:17±2:46±5 sccm, and Cl2 provided at a flow rate between 10 and 40 sccm. It was found that the width of the lower portion of the deep trench can be increased by 100% with minimum side effects such as polymer deposition in the plasma chamber, which could occur as result of substantially increased flow rate of HBr and/or NF3.

Claims20

Dependent claims

A method for forming a deep trench in a semiconductor substrate, comprising the steps of:

(a) forming a pad stacked layer on a substrate;
(b) forming a through hole in said pad stacked layer using a photolithography process;
(c) performing a second plasma etching process to form an upper trench section in said substrate, said second plasma etching process being performed using a second etching composition which comprises HBr, NF3, and a mixture of He and O2 at a second predetermined set of flow rates;
and
(d) performing a third plasma etching process to form a width-enlarged trench section in said substrate below said upper trench section, said third plasma etching process being performed using a third etching composition which comprises HBr, NF3, Cl2, and a mixture of He and O2 at a third predetermined set of flow rates.

2 more elements

Dependencies are inferred from the claim text.

Deep trench bottle-shaped etching using Cl2 gas

Life of this patent

Deep trench bottle-shaped etching using Cl2 gas

Life of this patent

Abstract

Claims20