Pad-less gate-all around semiconductor nanowire FETs on bulk semiconductor wafers

A method of forming a non-planar semiconductor device comprising:

• forming at least one semiconductor wire region within a bulk semiconductor substrate;
• providing a sacrificial spacer to vertical sidewalls of said at least one semiconductor wire region;
• removing portions of the bulk semiconductor substrate to provide an undercut beneath the sacrificial spacer and a vertical semiconductor pillar portion directly beneath the at least one semiconductor wire region;
• performing an oxidation process converting a recessed surface of the bulk semiconductor substrate into a horizontal semiconductor oxide portion, and converting the vertical semiconductor pillar portion into a vertical semiconductor oxide pillar portion;
• removing at least said vertical semiconductor oxide pillar portion and said sacrificial spacer forming at least one suspended semiconductor nanowire, while retaining at least a portion of said horizontal semiconductor oxide portion on said recessed surface of said semiconductor substrate, wherein said at least one suspended semiconductor nanowire has an end segment attached to a first semiconductor pad region and another end segment attached to a second semiconductor pad region, said first and second semiconductor pad regions are located above and are in direct contact with a non-recessed portion of the bulk semiconductor substrate;
• performing a hydrogen anneal on said at least one suspended semiconductor nanowire;
• providing a gate surrounding a central portion of said at least one suspended semiconductor nanowire;
• forming a spacer on opposing sides of said gate and covering a portion of said at least one suspended semiconductor nanowire;
• removing exposed portions of the at least one suspended semiconductor nanowire and said first and second semiconductor pad regions to provide at least one cut semiconductor nanowire having exposed end portions;
• and
• forming a source region located on a first side of the gate, and a drain region located on a second side of the gate which is opposite said first side of the gate.