US 5,269,880 A · Tapering sidewalls of via holes

Abstract

A method of tapering side walls of via holes and a tapered via hole structure for an integrated circuit is provided. Via holes having steep sidewalls are provided in an insulating layer overlying a conductive layer on a substrate, with an underlying conductive layer exposed at a bottom of each via hole. A protective layer is provided over the conductive layer in each via hole, and over the sidewalls. The via holes are then tapered by argon sputter etching to remove the protective layer and part of the insulating layer from the sidewall and around the peripheral edge of each via hole, thereby smoothly tapering the sidewall and providing a via hole increasing continuously in diameter from the bottom to the upper peripheral edge of the via hole. Via holes of multiple depths are simultaneously and smoothly tapered to the bottom of the via holes Any sputtered debris remaining in the via holes after the sputter etch step is removed by reactive ion etching to clean the conductive layer exposed in each via hole and allow for formation of reliable electrical contacts.

Claims14

Dependent claims

A method of tapering sidewalls of via holes comprising:

providing a substrate having a first conductive layer, an insulating layer overlying the conductive layer, the insulating layer defining therethrough a steep-sided via hole, the insulating layer forming a steep sidewall of the via hole extending from a peripheral edge to a bottom of the hole and the underlying conductive layer being exposed at the bottom of the via hole;
providing a protective layer of a uniform predetermined thickness extending over the insulating layer and over sidewalls of the via hole and over the exposed conductive layer within the via hole;
and
sputter etching the protective layer and the insulating layer to remove the protective layer and etch the insulating layer, whereby during sputter etching to remove the predetermined thickness of the protective layer from the conductive layer, material of the insulating layer is removed by sputtering from the peripheral edge and from the sidewall of the via hole thereby smoothly tapering the sidewall, to provide a tapered via hole increasing continuously in diameter from the bottom of the via hole towards the peripheral edge of the via hole.

1 more element

A method of tapering sidewalls of via holes for multilevel interconnect structures, comprising:

providing a substrate having a conductive layer and an overlying insulating layer, the insulating layer defining steep sidewalls of a plurality of deep and shallow via holes extending therethrough, a shallow via hole extending through a first thickness of the dielectric layer and a deep via hole extending through a second and greater thickness of the insulating layer, portions of the conductive layer being exposed within a bottom of each via hole;
providing a protective layer of a uniform predetermined thickness extending over the insulating layer and over sidewalls of each via hole and over the conductive layer exposed within each via hole;
and
sputter etching the protective layer and the insulating layer to remove the protective layer and etch the insulating layer, whereby during sputter etching to remove the predetermined thickness of the protective layer from the conductive layer in each via hole, material of the insulating layer is removed by sputtering from the peripheral edge and from the sidewall of each via hole thereby smoothly tapering each sidewall to provide a tapered via hole increasing continuously in diameter from the bottom of the via hole towards the peripheral edge of the via hole.

1 more element

Dependencies are inferred from the claim text.

Tapering sidewalls of via holes

Life of this patent

Tapering sidewalls of via holes

Life of this patent

Abstract

Claims14