Uniform height tall fins with varying silicon germanium concentrations

Abstract

A method of making a semiconductor device includes forming a first fin in a first semiconducting material layer disposed over a substrate, the first semiconducting material layer comprising an element in a first concentration; and forming a second fin in a second semiconducting material layer disposed over the substrate and adjacent to the first semiconducting material layer, the second semiconducting material layer comprising the element in a second concentration; wherein the first concentration is different than the second concentration.

1 .- 14 . (canceled) 
     
     
         15 . A semiconductor device, comprising:
 a first fin of a first transistor disposed over a substrate, the first fin comprising a semiconductor material comprising germanium in a first amount;   a second fin of a second transistor disposed over the substrate and adjacent to the first fin, the second fin comprising a semiconductor material comprising germanium in a second amount; and   a shallow trench isolation region arranged between the first fin and the second fin;   wherein the first amount is about 20 atomic % (at. %) to about 60 at. %, the second amount is about 10 at. % to about 20 at. %, the first fin and the second fin have substantially the same height, and the first transistor and the second transistor have different threshold voltages and different amounts of germanium;   wherein the first fin comprises a first substantially uniform concentration of germanium; and   wherein the second fin comprises a second substantially uniform concentration of germanium.   
     
     
         16 . The semiconductor device of  claim 15 , wherein the first fin comprises silicon germanium and the second fin comprises silicon germanium. 
     
     
         17 . The semiconductor device of  claim 15 , wherein the substrate comprises silicon, silicon carbide, germanium, silicon germanium, silicon germanium carbon, gallium arsenide, indium arsenide, indium phosphide, or any combination thereof. 
     
     
         18 .- 19 . (canceled) 
     
     
         20 . The semiconductor device of  claim 15 , further comprising a buried oxide layer disposed between the substrate and the first and second fins. 
     
     
         21 . (canceled) 
     
     
         22 . A semiconductor device, comprising:
 a first active area of a first transistor disposed over a substrate, the first active area comprising a first silicon layer and a first silicon germanium layer arranged on the first silicon layer; and   a second active area of a second transistor disposed over the substrate and adjacent to the first fin, the second active area comprising a second silicon layer and a second silicon germanium layer arranged on the second silicon germanium layer;   wherein the first silicon layer is recessed with respect to the second silicon layer and has a thickness that is different than the second silicon layer, and the first silicon germanium layer and the second silicon germanium layer have thicknesses that are the same.