Vertical transistor structures and methods utilizing selective formation

A complementary vertical field effect transistor (CFET) structure comprising:

• a stack of layers including:
• a first layer stack including at least first three layers of the at least one conductive material extending in the x-y plane separated in the z plane by one or more first layers of at least one dielectric material, the first layer stack associated with a first transistor structure;
• and
• a second layer stack including at least second three layers of at least one conductive material extending in the x-y plane separated in the z plane by one or more second layers of at least one dielectric material, the second layer stack associated with a second transistor structure,
• the first and second transistor structures separated by one or more dielectric materials;
• a channel opening extending through the stack of layers along the z plane;
• a first channel structure within the channel opening, the first channel structure comprising a semiconductive behaving oxide material and providing an N-type channel for the first transistor structure, wherein the first channel structure surrounds an insulating layer in the channel opening;
• and
• a second channel structure within the channel opening, the second channel structure comprising a semiconductive behaving oxide material and providing a P-type or N type channel for the second transistor structure, wherein the second channel structure surrounds the insulating layer in the channel opening and is separated apart from the first channel structure with the insulating layer.