Three-dimensional integrated circuits (3dics) including bottom gate mos transistors with monocrystalline channel material

An integrated circuit (IC) structure, comprising:

• a level of metallization over a first transistor structure;
• and
• a plurality of NMOS transistor structures over the level of metallization, the NMOS transistor structures comprising:
• a plurality of co-planar gate electrodes, each coupled with an interconnect feature of the level of metallization;
• a plurality of co-planar channel materials over corresponding ones of the gate electrodes, with a gate insulator therebetween, wherein the channel materials comprise a monocrystalline semiconductor;
• and
• a plurality of source and drain materials coupled to corresponding ones of the channel materials.

A method of fabricating a transistor structure, the method comprising:

• receiving a first substrate upon which there is a gate stack in contact with a channel material layer, the channel material layer comprising a monocrystalline semiconductor, and the gate stack comprising at least a gate insulator and a work function metal layer;
• receiving a second substrate comprising one or more levels of metallization interconnecting first transistors;
• transferring the gate stack and the channel material layer from the first substrate to the second substrate by bonding a metal layer of the gate stack to a second metal layer over the one or more levels of metallization;
• and
• forming a source material and a drain material coupled to separate portions of the channel material.