Backside dual dielectric fill for better thermal conductivity

A semiconductor device comprising:

• a first nanodevice including a plurality of first transistors, wherein the first nanodevice includes a first placeholder;
• a second nanodevice including a plurality of second transistors, wherein the second nanodevice is located adjacent to and parallel to the first nanodevice, wherein the second nanodevice includes a second placeholder;
• a BILD layer in direct contact with a first portion of sidewalls of the first placeholder, wherein the BILD layer is comprised of a first dielectric material;
• and
• a backside thermal dissipation dielectric in direct contact with a backside surface of the BILD layer, wherein the backside thermal dissipation dielectric is comprised of a second dielectric material.

A semiconductor device comprising:

• a first nanodevice including a plurality of first transistors, wherein the first nanodevice includes a first placeholder;
• a second nanodevice including a plurality of second transistors, wherein the second nanodevice is located adjacent to and parallel to the first nanodevice, wherein the second nanodevice includes a second placeholder;
• a BILD layer in direct contact with a first portion of sidewalls of the first placeholder, wherein the BILD layer is comprised of a first dielectric material;
• a backside thermal dissipation dielectric in direct contact with a backside surface of the BILD layer, wherein the backside thermal dissipation dielectric is comprised of a second dielectric material;
• and
• a backside source/drain contact having two separate horizontal frontside surfaces, wherein a first horizontal frontside surface of the two separate horizontal frontside surfaces is in direct contact with the backside surface of the BILD layer.