US 7,125,791 B2 · Advanced copper damascene structure

Abstract

A method of forming round bottom corners for conductive lines in an integrated circuit is presented. Two approaches are taken to achieve a preferred rounding profile. For both approaches, a trench is formed and conductive materials are filled in the trench. The etch stop layer (ESL) approach involves forming an ESL underlying an inter-level dielectric (ILD). After etching a trench in the ILD, the ESL is etched to further round trench corners. The chemistry approach involves changing the etching chemistry when etching the trench. The two approaches can be used separately or combined in the preferred embodiments of the present invention. In a preferred embodiment, a via structure comprising two copper lines and an interconnecting via is formed. By using the ESL and chemistry approaches, the bottom corners are formed substantially round. The preferred embodiment of the present invention is applied to conductive features that are close enough to cause time dependent dielectric breakdown.

Claims12

Dependent claims

A method for forming a via interconnection structure, the method comprising:

forming a first inter-level dielectric (ILD) over a substrate;
forming a first trench in the first ILD;
filling the first trench with conductive material to form a first conductive line;
forming a via etch stop layer (ESL) over the first ILD and the first conductive line;
forming a via ILD on the via ESL;
forming a trench ESL on the via ILD;
forming a trench ILD on the trench ESL;
etching a via opening through the trench ILD, trench ESL, via ILD and stopping at the via ESL;
etching a second trench through the trench ILD and stopping at the trench ESL;
etching the trench ESL to form a substantially round bottom corner of the second trench;
etching the exposed via ESL;
wherein the second trench has at least one bottom round corner with a substantially rounded portion having a horizontal width greater than about one fifth the total width of the second trench and a height greater than about one fourth the total height of the second trench;
and
filling the via and the second trench with conductive material.

11 more elements

Dependencies are inferred from the claim text.

Advanced copper damascene structure

Life of this patent

Advanced copper damascene structure

Life of this patent

Abstract

Claims12