Methods for wet etching of noble metals
AssigneeTokyo Electron Limited
InventorPaul Abel
Life of this patent
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Abstract
The present disclosure provides improved wet etch processes and methods for etching noble metals. More specifically, the present disclosure provides various embodiments of wet etch processes and methods that utilize new etch chemistries for etching noble metals, such as ruthenium (Ru), gold (Au), platinum (Pt) and iridium (Ir), in a wet etch process. In general, the disclosed embodiments expose a noble metal surface to a first etch solution to chemically modify the noble metal surface and form a noble metal salt passivation layer, which can then be selectively dissolved in a second etch solution to etch the noble metal surface.
Claims24
A method of etching, the method comprising:
- receiving a substrate having a noble metal formed thereon, wherein a noble metal surface is exposed on a surface of the substrate;
- exposing the surface of the substrate to a surface modification solution such that the surface modification solution is in contact with the noble metal surface, wherein the surface modification solution includes a persulfate salt, a chloride ion source and a cation, and wherein the persulfate salt reacts with the chloride ion source to form dichloride radical ions, which oxidize the noble metal surface to form a noble metal salt passivation layer;
- removing the surface modification solution from the surface of the substrate subsequent to forming the noble metal salt passivation layer;
- exposing the surface of the substrate to a dissolution solution that reacts with the noble metal salt passivation layer to form soluble species that are dissolved by the dissolution solution;
- and
- removing the dissolution solution and the soluble species from the substrate.
A method of etching, the method comprising:
- receiving a substrate having a noble metal formed thereon, wherein a noble metal surface is exposed on a surface of the substrate;
- exposing the surface of the substrate to a surface modification solution such that the surface modification solution is in contact with the noble metal surface, wherein the surface modification solution includes:
- (a) a chloride ion source, (b) a persulfate salt that reacts with the chloride ion source to form dichloride radical ions, which oxidize the noble metal surface to form a noble metal salt passivation layer, and (c) an acid or a base to adjust a pH of the surface modification solution and control an oxidation behavior of the noble metal salt passivation layer;
- removing the surface modification solution from the surface of the substrate subsequent to forming the noble metal salt passivation layer;
- exposing the surface of the substrate to a dissolution solution that reacts with the noble metal salt passivation layer to form soluble species that are dissolved by the dissolution solution;
- and
- removing the dissolution solution and the soluble species from the substrate.
A method of etching a substrate using a wet atomic layer etching (ALE) process, the method comprising:
- a) receiving the substrate, the substrate having a noble metal layer thereon;
- b) exposing the noble metal layer to a first etch solution containing a non-acidic chloride ion source, a base and an oxidizer that reacts with the non-acidic chloride ion source to form dichloride radical ions, which oxidize an exposed surface of the noble metal layer to form a chemically modified noble metal surface layer containing a chloro-metalate salt, an oxychlorometalate salt or a hydrate of the chloro-metalate salt or the oxychlorometalate salt, which is self-limiting and insoluble in the first etch solution;
- c) rinsing the substrate with a first purge solution to remove the first etch solution from a surface of the substrate;
- d) exposing the chemically modified noble metal surface layer to a second etch solution to dissolve the chemically modified noble metal surface layer;
- e) rinsing the substrate with a second purge solution to remove the second etch solution from the surface of the substrate;
- and
- f) repeating steps b)-e) for one or more cycles.
Dependencies are inferred from the claim text.