Lithium drifted thin film transistors for neuromorphic computing

A semiconductor device, comprising:

• an array of resistive processing unit devices, wherein each resistive processing unit device in the array comprises:
• a field-effect transistor integrated between a first back-end-of-line metallization level and a second back-end-of-line metallization level above the first back-end-of-line metallization level;
• wherein a portion of each field-effect transistor comprises lithium therein;
• wherein each field-effect transistor comprises a channel layer, a source region, a drain region, and a gate dielectric layer disposed on top surfaces of the channel layer, the source region and the drain region;
• wherein a gate of each field-effect transistor is electrically connected to a contact of the second back-end-of-line metallization level and is disposed on a top surface of the gate dielectric layer;
• wherein the source region and the drain region comprise the lithium therein;
• and
• wherein the lithium in the source region is at a higher concentration at an upper portion than at a lower portion of the source region;
• wherein the lithium in the drain region is at a higher concentration at an upper portion than at a lower portion of the drain region;
• and
• wherein the source region and the drain region are electrically connected to one or more contacts in the second back-end-of-line metallization level by respective vias located between the first and second back-end-of-line metallization levels and extending through the gate dielectric layer.