Transistor contacts and methods of forming thereof

A device comprising:

• a first source/drain region in a first transistor layer;
• a first conductive line in a dielectric layer over the first source/drain region;
• a second source/drain region over the first conductive line, the second source/drain region being disposed in a second transistor layer;
• a first source/drain contact extending through the first source/drain region and touching the first conductive line;
• a first silicide region on a sidewall of the first source/drain contact and a sidewall of the first source/drain region;
• a second source/drain contact extending through the second source/drain region and touching the first conductive line, wherein the first source/drain region is electrically connected to the second source/drain region by the first source/drain contact, the second source/drain contact, and the first conductive line;
• and
• a second silicide region on a sidewall of the second source/drain contact and a sidewall of the second source/drain region.

A device comprising:

• a first gate electrode disposed in a first transistor layer;
• a second gate electrode disposed in a second transistor layer, wherein the first transistor layer and the second transistor layer are vertically stacked;
• an interconnect structure between the first transistor layer and the second transistor layer, the interconnect structure comprising a first conductive line;
• a first gate contact electrically connected to the first gate electrode, wherein the first gate contact extends through the first gate electrode;
• and
• a second gate contact electrically connected to the second gate electrode, wherein the first conductive line extends from a surface of the first gate contact to a surface of the second gate contact, and wherein the second gate contact extends through the second gate electrode.