Heat dissipation for semiconductor devices and methods of manufacture

A method comprising:

• forming a first transistor on a first substrate;
• exposing a first epitaxial material, wherein exposing the first epitaxial material comprises thinning a backside of the first substrate;
• replacing the first epitaxial material with a first backside via, the first backside via being electrically coupled to a first source/drain region of the first transistor;
• forming a backside interconnect structure over the first backside via opposite the first source/drain region;
• and
• coupling a first heat dissipation substrate to the backside interconnect structure opposite the first backside via.

A device comprising:

• a first transistor structure comprising a gate structure over a semiconductor channel region;
• a first interconnect structure on a first side of the first transistor structure, the first interconnect structure comprising first conductive lines;
• a second interconnect structure on a second side of the first transistor structure, the second side being opposite the first side, the second interconnect structure comprising second conductive lines, the second conductive lines having line widths greater than line widths of the first conductive lines;
• and
• a first heat dissipation substrate coupled to the second interconnect structure.