Multilayer electrical interconnect fabrication with few process steps

Claim 1

A method of making a multilayer electrical interconnect, comprising the following steps in the sequence set forth: depositing an adhesion layer on a planar base; depositing a layer of an electrically conductive first metal on the adhesion layer; depositing a mask on the first metal, the mask comprising an opening above a portion of the first metal; wet etching said portion of the first metal and the underlaying adhesion layer, and removing the mask, thereby leaving unetched first metal on the base; depositing a layer of dielectric over the unetched first metal; forming a via in the dielectric above the unetched first metal; depositing an electrically conductive second metal into the via, wherein the second metal fills the via with a metal pillar in electrical contact with the unetched first metal; and planarizing the top surface of the interconnect.

Claim 2

A method of making a multilayer electrical interconnect, comprising the following steps in the sequence set forth: depositing an adhesion layer on a planar base; depositing a layer of an electrically conductive first metal on the adhesion layer; depositing a mask on the first metal, the mask comprising an opening above a portion of the first metal; wet etching said portion of the first metal and the underlaying adhesion layer, and removing the mask, thereby leaving unetched first metal on the base; depositing a layer of dielectric over the unetched first metal; forming a via in the dielectric above the unetched first metal; depositing an electrically conductive second metal into the via, wherein the second metal fills the via with a metal pillar in electrical contact with the unetched first metal; and planarizing the top surface of the interconnect.

Claim 17

A method of making a multilayer electrical interconnect, comprising the following steps in the sequence set forth: providing a dielectric; depositing an adhesion layer of titanium or chromium on the dielectric; depositing a layer of copper on the adhesion layer; depositing a photoresist mask over the copper, wherein the photoresist mask has an opening which exposes a portion of the copper; wet etching the exposed copper and underlaying adhesion metal, and stripping the photoresist mask, thereby leaving an unetched horizontal copper line adhering to the dielectric; depositing a layer of polymer over the unetched copper; forming a vertical via in the polymer above the unetched copper; depositing a pillar metal comprising copper or nickel into the via so that the pillar metal fills the via and electrically contacts the unetched copper; and polishing the top of the interconnect to form a planar top surface.

Claim 18

A method of making a multilayer electrical interconnect, comprising the following steps in the sequence set forth: providing a dielectric; depositing an adhesion layer of titanium or chromium on the dielectric; depositing a layer of copper on the adhesion layer; depositing a photoresist mask over the copper, wherein the photoresist mask has an opening which exposes a portion of the copper; wet etching the exposed copper and underlaying adhesion metal, and stripping the photoresist mask, thereby leaving an unetched horizontal copper line adhering to the dielectric; depositing a layer of polymer over the unetched copper; forming a vertical via in the polymer above the unetched copper; depositing a pillar metal comprising copper or nickel into the via so that the pillar metal fills the via and electrically contacts the unetched copper; and polishing the top of the interconnect to form a planar top surface.

Claim 22

A method of making a multilayer electrical interconnect, comprising the following steps in the sequence set forth: providing a dielectric base; depositing an adhesion metal of chromium or titanium on the dielectric base; depositing a copper on the adhesion metal; depositing a protective metal of chromium or titanium on the copper; depositing photoresist on the protective metal; forming a plurality of openings by photo-lithography in the photoresist above the protective metal; applying a wet chemical etch to remove the protective metal, copper and adhesive metal beneath the photoresist openings; stripping the photoresist from the interconnect; depositing a layer of polyimide over the unetched protective metal, copper and adhesion metal; forming a plurality of vertical vias in the polyimide, wherein each via is positioned above the unetched copper; applying a second etch to remove the protective metal between the vias and the unetched copper; depositing by one of electroless deposition or chemical vapor deposition a pillar metal which contains copper or nickel into the vias so that each via is filled with a metal pillar in electrical contact with underlaying unetched copper; and polishing the interconnect to form a planar top surface.

Claim 23

A method of making a multilayer electrical interconnect, comprising the following steps in the sequence set forth: providing a dielectric base; depositing an adhesion metal of chromium or titanium on the dielectric base; depositing a copper on the adhesion metal; depositing a protective metal of chromium or titanium on the copper; depositing photoresist on the protective metal; forming a plurality of openings by photo-lithography in the photoresist above the protective metal; applying a wet chemical etch to remove the protective metal, copper and adhesive metal beneath the photoresist openings; stripping the photoresist from the interconnect; depositing a layer of polyimide over the unetched protective metal, copper and adhesion metal; forming a plurality of vertical vias in the polyimide, wherein each via is positioned above the unetched copper; applying a second etch to remove the protective metal between the vias and the unetched copper; depositing by one of electroless deposition or chemical vapor deposition a pillar metal which contains copper or nickel into the vias so that each via is filled with a metal pillar in electrical contact with underlaying unetched copper; and polishing the interconnect to form a planar top surface.