Selective etching of copper and copper-barrier materials by an aqueous base solution with fluoride addition
AssigneeIntermolecular, Inc.
InventorsAnh Duong, Errol Todd Ryan
Life of this patent
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Abstract
Wet-etch solutions for conductive metals (e.g., copper) and metal nitrides (e.g., tantalum nitride) can be tuned to differentially etch the conductive metals and metal nitrides while having very little effect on nearby oxides (e.g., silicon dioxide hard mask materials), and etching refractory metals (e.g. tantalum) at an intermediate rate. The solutions are aqueous base solutions (e.g., ammonia-peroxide mixture or TMAH-peroxide mixture) with just enough hydrofluoric acid (HF) added to make the solution's pH about 8-10. Applications include metallization of sub-micron logic structures.
Claims17
A method of simultaneously etching a metal and a metal nitride, the method, comprising:
- exposing the metal and the metal nitride to a solution comprising hydrofluoric acid and a base;
- wherein the solution has a pH in a range of about 8 to about 10;
- and
- wherein the solution etches less than about 10 angstroms of silicon dioxide per second at a temperature of about 40° C.;
- wherein the solution etches the metal nitride to a first recess level and etches the metal to a second recess level.
A method of making a semiconductor device, the method comprising:
- providing a substrate comprising a hard mask over a dielectric;
- forming an opening through the hard mask into the dielectric;
- lining the opening with a barrier;
- filling the opening with a conductor;
- removing the barrier, the conductor, and a portion of the hard mask from an area of the substrate outside the opening;
- and
- simultaneously etching the barrier to a first recess level and etching the conductor to a second recess level;
- wherein the etching comprises exposing the substrate to a solution comprising hydrofluoric acid and a base;
- wherein the first recess level is lower than a top surface of the substrate;
- and
- wherein the second recess level is lower than the first recess level.
Dependencies are inferred from the claim text.