Facilitating fabricating gate-all-around nanowire field-effect transistors

Abstract

Methods are presented for facilitating fabrication of a semiconductor device, such as a gate-all-around nanowire field-effect transistor. The methods include, for instance: providing at least one stack structure including at least one layer or bump extending above the substrate structure; selectively oxidizing at least a portion of the at least one stack structure to form at least one nanowire extending within the stack structure(s) surrounded by oxidized material of the stack structure(s); and removing the oxidized material from the stack structure(s), exposing the nanowire(s). This selectively oxidizing may include oxidizing an upper portion of the substrate structure, such as an upper portion of one or more fins supporting the stack structure(s) to facilitate full 360° exposure of the nanowire(s). In one embodiment, the stack structure includes one or more diamond-shaped bumps or ridges.

1 . A method comprising:
 facilitating fabrication of a semiconductor device comprising multiple nanowires, the facilitating comprising:   forming a first stack structure comprising at least one layer or bump extending above a substrate structure;   after forming said first stack structure, forming a second stack structure on said first stack structure comprising at least one layer or bump extending above the substrate;   selectively oxidizing at least a portion of the first and second stack structure to form multiple nanowires extending within each of said first and second stack structure by oxidized material; and   removing the oxidized material from the first and second stack structure, exposing the multiple nanowires.   
     
     
         2 . The method of  claim 1 , wherein
 the multiple nanowires extending in substantially parallel, vertical alignment.   
     
     
         3 . The method of  claim 2 , comprising growing multiple alternating layers of silicon-germanium (SiGe) and silicon (Si) over the substrate structure and etching the multiple layers to provide the first or second stack structure. 
     
     
         4 . The method of  claim 3 , wherein the selectively oxidizing concentrates the germanium (Ge) of the silicon-germanium (SiGe) layers into the multiple nanowires. 
     
     
         5 . The method of  claim 1 , wherein the selectively oxidizing further comprises oxidizing an upper portion of the substrate structure, and the removing comprises removing oxidized material from the upper portion of the substrate structure to facilitate full 360° exposure of the at least one nanowire. 
     
     
         6 . The method of  claim 5 , wherein the substrate structure comprises silicon (Si), and the at least one layer or bump of said first stack structure or second stack structure comprises silicon-germanium (SiGe). 
     
     
         7 . The method of  claim 1 , wherein the removing comprises etching away the oxidized material to achieve full 360° exposure of at least a portion of the at least one nanowire. 
     
     
         8 . The method of  claim 1 , wherein the at least one layer or bump of the first stack structure or second stack structure comprises at least one bump extending above the substrate structure, each bump being configured as a diamond-shaped bump. 
     
     
         9 . The method of  claim 8 , wherein the forming a first stack structure and, forming a second stack structure comprises epitaxially growing the diamond-shaped bump(s) above the substrate structure. 
     
     
         10 . The method of  claim 8 , wherein the substrate structure comprises at least one fin extending above a substrate, the at least one bump being part of or extending from the at least one fin at an upper portion of the at least one fin. 
     
     
         11 . The method of  claim 10 , wherein the selectively oxidizing comprises selectively oxidizing the upper portion of the at least one fin, and the removing comprises removing, at least in part, the oxidized material from the upper portion of the at least one fin to facilitate full 360° exposure of at least a portion of the at least one nanowire. 
     
     
         12 . The method of  claim 11 , wherein the removing further comprises providing an oxide layer covering over the first or second stack structure, planarizing the oxide layer, and etching back the oxide layer and the oxide material to reveal the at least one nanowire. 
     
     
         13 . The method of  claim 8 , wherein the forming a first stack structure and thereafter, forming a second stack structure results in multiple stacked bumps extending above the substrate structure, the multiple stacked bumps comprising the at least one bump and each being configured as a diamond-shaped bump, with one diamond-shaped bump being disposed above another diamond-shaped bump of the multiple stacked bumps of the at least one stack structure. 
     
     
         14 . The method of  claim 13 , wherein the providing comprises:
 forming, via a first epitaxial process, a first diamond-shaped bump of the multiple stacked bumps extending from an upper portion of the substrate structure;   providing a hard-mask layer conformally wrapping around the first diamond-shaped bump;   etching the hard-mask layer to reveal an upper portion of the first diamond-shaped bump;   forming, via a second epitaxial process, a second diamond-shaped bump extending from the upper portion of the first diamond-shaped bump; and   removing the hard-mask layer from the first diamond-shaped bump to reveal the multiple stacked bumps.   
     
     
         15 . The method of  claim 14 , wherein the hard-mask layer comprises one of an oxide or a nitride conformally wrapping around the first diamond-shaped bump. 
     
     
         16 . The method of  claim 13 , wherein the forming a first stack structure and thereafter, forming a second stack structure comprises:
 forming, via a first epitaxial process, a first diamond-shaped bump of the multiple stacked bumps extending from an upper portion of the substrate structure;   depositing an isolation layer covering over the first diamond-shaped bump;   etching the isolation layer to reveal an upper portion of the first diamond-shaped bump;   forming, via a second epitaxial process, a second diamond-shaped bump extending from the upper portion of the first diamond-shaped bump; and   further etching the isolation layer to reveal the first diamond-shaped bump and the second diamond-shaped bump of the multiple stacked bumps.   
     
     
         17 . The method of  claim 1 , wherein the first and second stack structure comprises:
 multiple bumps, the multiple bumps being part of or extending above a fin of the substrate structure, and the multiple bumps comprising the at least one layer or bump of the at least one stack structure, wherein each bump is configured as a diamond-shaped bump; and   the selectively oxidizing the at least a portion of the at least one stack structure facilitates forming multiple nanowires extending therein surrounded by the oxidized material of the at least one stack structure; and   the removing of the oxidized material from the at least one stack structure exposes the multiple nanowires, the multiple nanowires extending in substantially parallel, vertical alignment.   
     
     
         18 . The method of  claim 17 , further comprising, prior to the selectively oxidizing, removing an upper portion of an isolation layer at least partially surrounding the fin of the substrate structure to expose an upper portion of the fin, and wherein the selectively oxidizing comprises selectively oxidizing the upper portion of the fin, and the removing comprises removing, at least in part, oxidized material from the upper portion of the fin to facilitate full 360° exposure of at least a portion of one nanowire of the multiple nanowires. 
     
     
         19 . The method of  claim 17 , wherein the selectively oxidizing leaves unoxidized at least a first support portion and a second support portion of the multiple bumps at opposite ends of the multiple nanowires to support the multiple nanowires upon the removing of the oxidized material from the at least one stack structure. 
     
     
         20 . The method of  claim 19 , wherein the semiconductor device comprises a fin field-effect transistor, the first support portion of the multiple bumps is a source region of the fin field-effect transistor, and the second support portion of the multiple bumps is a drain region of the fin field-effect transistor. 
     
     
         21 . The method of  claim 1 , further comprising providing a first support and a second support at opposite ends of the multiple nanowires to support the at least one nanowire upon the removing of the oxidized material from the at least one stack structure, the multiple nanowires existing in part within the first and second support.