US 5,670,019 AGranted

Removal process for tungsten etchback precipitates

AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.

InventorYuan-Chang Huang

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Abstract

This invention provides a method of cleaning integrated circuit wafers which effectively removes precipitates formed as a result of the tungsten etchback process. When tungsten is used to fill via holes in an inter-metal dielectric layer an adhesion layer of titanium nitride, TiN, is required to provide good adhesion. As a result of the tungsten etchback, wherein fluorine based etchants are used, precipitates of TiF.sub.3 can form which are extremely difficult to remove. Methods, such as in-situ bake after the tungsten etchback, are used to prevent the formation of the precipitates but do not remove them after they are formed. This invention teaches a method using a strong oxidizing agent, such as H.sub.2 O.sub.2, to cause an oxidation-reduction reaction which converts the precipitates to a water soluble form. The water soluble form of the precipitates are then removed using a water rinse and spin dry process.

Claims20

Dependent claims

A method of cleaning integrated circuit wafers, comprising the steps of:

providing an integrated circuit wafer having devices formed therein and an inter-metal dielectric formed thereon;
providing via holes formed in said inter metal dielectric wherein each said via hole has sidewalls and a bottom;
forming a titanium nitride adhesion layer over said inter-metal dielectric layer, said sidewalls of each said via hole, and said bottom of each said via hole;
forming a conduction metal layer over said titanium nitride adhesion layer thereby filling said via holes with said conduction metal;
etching away that part of said conduction metal layer not filling said via holes and that part of said titanium nitride adhesion layer not on said sidewalls and bottom of each said via hole using dry etching with a fluorine based etchant;
immersing said integrated circuit wafer in an oxidizing agent having a first temperature for a first time, after said metal etchback process has been completed;
immersing said integrated circuit wafer in water having a second temperature for a second time after immersing said integrated circuit wafer in said oxidizing agent has been completed;
and
drying said wafer after said immersing said wafer in said water has been completed.

6 more elements

Dependencies are inferred from the claim text.