Fabrication of fin field effect transistors utilizing different fin channel materials while maintaining consistent fin widths

A method of forming vertical fins on a substrate at the same time, the method comprising:

• forming a mask segment on a first region of the substrate while exposing the surface of a second region of the substrate;
• removing a portion of the substrate in the second region to form a recess;
• forming a fin layer in the recess, where the fin layer has a different material composition than the substrate;
• removing the mask segment from the first region of the substrate;
• forming a fin template layer on the first region of the substrate and the fin layer in the recess;
• forming a mandrel layer on at least a portion of the fin template layer;
• forming a mandrel template layer on the mandrel layer;
• patterning the mandrel template layer, mandrel layer, and fin template layer to form one or more fin templates on the first region of the substrate and one or more fin templates on the second region of the substrate;
• forming a vertical fin below each of the one or more fin templates on the first region of the substrate and below each of the one or more fin templates on the second region of the substrate, wherein the one or more vertical fins on the second region of the substrate includes a fin layer pillar formed from the fin layer and a substrate pillar;
• removing a portion of each of the fin templates to form fin template posts on each of the one or more vertical fins on the first region of the substrate and each of the one or more vertical fins on the second region of the substrate, wherein the fin template posts have a width less than a width of the underlying vertical fin;
• forming a filler layer on a lower portion of the one or more vertical fins on the first region of the substrate and the one or more vertical fins on the second region of the substrate, wherein the filler layer includes a dopant, and wherein at least a portion of the fin layer pillar is exposed above the filler layer;
• forming a composite fin layer on the sidewalls of the one or more vertical fins on the first region of the substrate and a composite pillar layer on the one or more fin layer pillars on the second region of the substrate, wherein a flared fin section is formed by each of the one or more vertical fins on the first region of the substrate and a flared pillar section is formed by each of the one or more vertical fins on the second region of the substrate, and the flared fin section and flared pillar section are each below a top surface of the filler layer;
• and
• diffusing the dopant from the filler layer into the lower portion of the one or more vertical fins on the first region of the substrate and the one or more vertical fins on the second region of the substrate to form a punch-through stop below an upper portion of the one or more vertical fins on the first region of the substrate, and a punch-through stop below an upper portion of the one or more vertical fins on the second region of the substrate.