Methods for wet atomic layer etching of tungsten using halogenation
AssigneeTokyo Electron Limited
InventorsTulashi Dahal, Kate Abel
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Abstract
Various embodiments of methods are provided for etching tungsten in a wet ALE process. The methods disclosed herein use a wide variety of wet etch chemistries to: (a) halogenate a tungsten surface and form a self-limiting, tungsten halide passivation layer in a surface modification step of the wet ALE process, and (b) selectively remove the tungsten halide passivation layer in a dissolution step of the wet ALE process. In the embodiments disclosed herein, a surface modification solution containing a halogenation agent dissolved in non-aqueous solvent is used to form a self-limiting, tungsten halide passivation layer, which is selectively removed in an aqueous dissolution solution via reactive dissolution/hydrolysis.
Claims23
A method of etching, the method comprising:
- receiving a substrate having a tungsten (W) layer formed thereon, wherein a tungsten surface is exposed on a surface of the substrate;
- exposing the surface of the substrate to a surface modification solution comprising a halogenation agent dissolved in a non-aqueous solvent, wherein the halogenation agent reacts with the tungsten surface to form a tungsten halide passivation layer, which is self-limiting and insoluble in the surface modification solution;
- removing the surface modification solution from the surface of the substrate subsequent to forming the tungsten halide passivation layer;
- exposing the surface of the substrate to a dissolution solution to selectively remove the tungsten halide passivation layer, wherein the dissolution solution reacts with the tungsten halide passivation layer to form soluble species, which are dissolved by the dissolution solution to expose an unmodified tungsten surface underlying the tungsten halide passivation layer;
- and
- removing the dissolution solution and the soluble species from the surface of the substrate to etch the tungsten layer.
A method of etching a substrate using a wet atomic layer etching (ALE) process, the method comprising:
- receiving the substrate, the substrate having a tungsten (W) layer formed thereon, wherein a tungsten surface is exposed on a surface of the substrate;
- and
- selectively etching the tungsten layer by performing multiple cycles of the wet ALE process, wherein each cycle comprises:
- exposing the tungsten surface to a first etch solution comprising an electrophilic chlorinating agent dissolved in a non-aqueous solvent to form a chemically modified W surface layer that is self-limiting and insoluble in the non-aqueous solvent;
- rinsing the substrate with a first purge solution to remove the first etch solution from the surface of the substrate;
- exposing the chemically modified W surface layer to a second etch solution to selectively dissolve the chemically modified W surface layer and expose an unmodified tungsten surface underlying the chemically modified W surface layer;
- and
- rinsing the substrate with a second purge solution to remove the second etch solution from the surface of the substrate and etch the tungsten layer.
Dependencies are inferred from the claim text.