Vertical fet with asymmetric threshold voltage and channel thicknesses

11:

• A field effect transistor, FET, comprising:
• a source;
• a drain;
• a channel between the source and drain, the channel having a source side electrically connected to the source and a drain side electrically connected to the drain, the channel having a first region with a first thickness and a first length and a second region with a second thickness and a second length, the first thickness being thinner than the second thickness;
• and
• a gate encompassing the channel,
• where a threshold voltage, Vth, in the first region is higher than the Vth in the second region and where there is an asymmetric Vth over a length of the channel.

13:

• A method of making a FET comprising the steps of:
• creating a structure with a substrate, an implantation layer disposed upon the substrate, a fin top layer disposed on the implantation layer, and a hard mask layer disposed on the fin top layer, where the implantation layer is created by implantation of with one of Chlorine (Cl) and Fluorine (F);
• forming one or more fins, each of the fins having one or more non-implanted regions, an implanted region derived from the implantation layer, and a fin top;
• forming a bottom source/drain on the substrate and around a bottom of each of the fins;
• disposing a bottom spacer on the bottom source/drain layer;
• reducing a first thickness of the implanted region to be thinner than a second thickness of the non-implanted region;
• forming a gate;
• forming a top spacer;
• forming a top source/drain on the fin top;
• and
• forming a contact to the top source/drain, the bottom source/drain, and gate.

15:

• A method, as in claim 13, where the first thickness of the implanted region is reduced by following steps:
• oxidizing the implanted region to form a first oxidation thickness;
• and
• removing the first oxidation thickness.

16:

• A method, as in claim 13, further comprising the following steps:
• oxidizing the implanted region to form a first oxidation thickness;
• simultaneously oxidizing the non-implanted region to form a second oxidation thickness, the first oxidation thickness being thicker than the second oxidation thickness because the implanted region oxidizes faster than the non-implanted region;
• and
• removing the first and second oxidation thicknesses so that the implanted region becomes thinner than the non-implanted region.

18:

• A method, as in claim 13, where an implanted region thickness is reduced by:
• oxidizing the implanted region at a temperature below 700 degrees Celsius to form a first oxidation thickness;
• and
• removing the first oxidation thickness.