FINFET STRUCTURES HAVING SILICON GERMANIUM AND SILICON FINS
A finned structure is fabricated using a bulk silicon substrate having a carbon doped epitaxial silicon layer. A pFET region of the structure includes silicon germanium fins. Such fins are formed by annealing the structure to mix a germanium containing layer with an adjoining crystalline silicon layer. The structure further includes an nFET region including silicon fins formed from the crystalline silicon layer. The germanium containing layer in the nFET region is removed to create a space beneath the crystalline silicon layer in the nFET region. An insulating material is provided within the space. The pFET and nFET regions are electrically isolated by a shallow trench isolation region.
1 . A structure comprising:
a bulk silicon substrate;
an epitaxial carbon doped silicon layer on the bulk silicon substrate;
a plurality of fins comprising silicon germanium adjoining a first portion of the epitaxial carbon doped silicon layer;
an insulating layer adjoining a second portion of the epitaxial carbon doped silicon layer;
a plurality of fins comprising crystalline silicon adjoining the insulating layer, and
an isolation region electrically isolating the first and second portions of the epitaxial carbon doped silicon layer.
2 . The structure of claim 1 , further including an isolation layer extending between the silicon germanium fins.
3 . The structure of claim 1 , wherein the fins comprising crystalline silicon have side walls comprising ( 110 ) surfaces.
4 . The structure of claim 1 , wherein the crystalline silicon fins are fifty nanometers or less in height.
5 . The structure of claim 4 , wherein the insulating layer is an oxide layer.
6 . The structure of claim 5 , wherein the oxide layer has a thickness between five and twenty-five nanometers.