P-FET WITH GRADED SILICON-GERMANIUM CHANNEL
A method of forming a semiconductor structure includes etching a semiconductor region of a substrate to form a thinned semiconductor region, and forming a silicon-germanium layer on the thinned semiconductor region, the silicon-germanium layer having a graded concentration profile of germanium atoms.
1 . A method of forming a semiconductor structure, the method comprising:
etching a semiconductor region of a substrate to form a thinned semiconductor region; and
forming a silicon-germanium layer on the thinned semiconductor region, the silicon-germanium layer having a graded concentration profile of germanium atoms.
2 . The method of claim 1 , wherein the thinned semiconductor region comprises a thinned silicon fin or a thinned silicon ETSOI layer.
3 . The method of claim 1 , wherein forming the silicon-germanium layer comprises epitaxially growing the silicon-germanium layer on opposite sidewalls of the thinned silicon fin to form a graded silicon-germanium fin.
4 . The method of claim 1 , wherein forming the silicon-germanium layer comprises epitaxially growing the silicon-germanium layer above and in direct contact with a top surface of the thinned silicon ETSOI layer to form a graded ETSOI layer.
5 . The method of claim 1 , wherein the graded concentration profile of germanium atoms is achieved by varying an amount of germanium atoms in a source gas during epitaxial growth of the silicon-germanium layer.
6 . A method of forming a semiconductor structure, the method comprising:
forming a silicon fin on a semiconductor substrate;
etching the silicon fin to substantially reduce a width of the silicon fin; and
forming a silicon-germanium layer on opposite sidewalls of the etched silicon fin to form a silicon-germanium fin, wherein a concentration of germanium atoms in the silicon-germanium fin continuously increases from a center of the silicon-germanium fin to outer edges of the silicon-germanium fin.
7 . The method of claim 6 , wherein forming the silicon-germanium layer comprises epitaxially growing the silicon-germanium layer with a layered germanium concentration profile.
8 . The method of claim 7 , wherein epitaxially growing the silicon-germanium layer with the layered germanium concentration profile comprises varying an amount of germanium atoms in a source gas during epitaxial growth of the silicon-germanium layer to form a graded silicon-germanium layer.
9 . The method of claim 8 , wherein the graded silicon-germanium layer comprises a plurality of sub-layers, each sub-layer in the plurality of sub-layers has an increasing concentration of germanium atoms.
10 . The method of claim 6 , wherein the concentration of germanium atoms in the silicon-germanium fin continuously increasing from a center of the silicon-germanium fin to outer edges of the silicon-germanium fin allows holes to be substantially near a subsequently formed gate structure.