Non-planar semiconductor device having omega-fin with doped sub-fin region and method to fabricate same
Non-planar semiconductor devices having omega-fins with doped sub-fin regions and methods of fabricating non-planar semiconductor devices having omega-fins with doped sub-fin regions are described. For example, a semiconductor device includes a plurality of semiconductor fins disposed above a semiconductor substrate, each semiconductor fin having a sub-fin portion below a protruding portion, the sub-fin portion narrower than the protruding portion. A solid state dopant source layer is disposed above the semiconductor substrate, conformal with the sub-fin region but not the protruding portion of each of the plurality of semiconductor fins. An isolation layer is disposed above the solid state dopant source layer and between the sub-fin regions of the plurality of semiconductor fins. A gate stack is disposed above the isolation layer and conformal with the protruding portions of each of the plurality of semiconductor fins.
1. A method of fabricating a semiconductor device, the method comprising:
forming a plurality of semiconductor fins above a semiconductor substrate;
forming a catalyst layer above the semiconductor substrate, conformal with the plurality of semiconductor fins;
forming a mask above the catalyst layer;
recessing the mask and the catalyst layer to a same level below a top surface of the plurality of semiconductor fins, the recessing exposing a protruding portion of each of the plurality of semiconductor fins above a sub-fin region of each of the plurality of semiconductor fins;
oxidizing outer portions of the sub-fin region of each of the plurality of semiconductor fins using the catalyst layer to catalytically oxidize the sub-fin region; and
removing oxide formed from the oxidizing to provide a plurality of omega-fins each having a thinned sub-fin region narrower than the corresponding protruding portion.
2. The method of claim 1 , wherein the plurality of semiconductor fins is a plurality of silicon fins, and wherein forming the catalyst layer comprises forming a layer of Al 2 O 3 conformal with the plurality of silicon fins.
3. The method of claim 2 , wherein oxidizing the outer portions of the sub-fin region comprises exposing the layer of Al 2 O 3 to a combination of hydrogen and oxygen (H 2 /O 2 ).
4. The method of claim 1 , further comprising:
subsequent to providing the plurality of omega-fins, forming a solid state dopant source layer above the semiconductor substrate, conformal with the plurality of omega-fins;
recessing the solid state dopant source layer to be co-planar with the thinned sub-fin region of each of the plurality of omega-fins; and
driving dopants from the solid state dopant source layer into the thinned sub-fin region of each of the plurality of omega-fins.
5. The method of claim 4 , wherein forming the solid state dopant source layer comprises forming a borosilicate glass (BSG) layer.
6. The method of claim 4 , wherein forming the solid state dopant source layer comprises forming a phosphosilicate glass (PSG) layer or an arsenic silicate glass (AsSG) layer.
7. The method of claim 1 , further comprising:
forming a gate stack conformal with the protruding portion of each of the plurality of omega-fins; and
forming source and drain regions in the protruding portion of each of the plurality of omega-fins, on either side of the gate stack.