Method and structure to suppress FinFET heating
Embodiments of the present invention provide structures and methods for heat suppression in finFET devices. Fins are formed in a semiconductor substrate. A graphene layer is formed on a lower portion of the sidewalls of the fins. A shallow trench isolation region is disposed on the structure and covers the graphene layer, while an upper portion of the fins protrudes from the shallow trench isolation region. The graphene layer may also be deposited on a top surface of the base semiconductor substrate. The graphene serves to conduct heat away from the fins more effectively than other dielectric materials.
1. A method of forming a semiconductor structure, comprising:
forming a plurality of fins on a semiconductor substrate;
forming a graphene layer on the plurality of fins;
depositing a first shallow trench isolation layer disposed over the graphene layer to an intermediate level of the plurality of fins;
recessing the graphene layer to the intermediate level; and
depositing a second shallow trench isolation layer disposed over the first shallow trench isolation layer, such that the graphene layer is covered by the second shallow trench isolation layer while an upper portion of each fin of the plurality of fins is exposed.
2. The method of claim 1 , further comprising depositing a protective layer over the graphene layer prior to depositing the first shallow trench isolation layer.
3. The method of claim 2 , wherein depositing a protective layer over the graphene layer comprises depositing a silicon nitride layer.
4. The method of claim 1 , wherein forming a graphene layer comprises:
depositing a layer of silicon carbide; and
performing an anneal to form the graphene layer by sublimating silicon in the silicon carbide layer.
5. The method of claim 4 , wherein depositing a layer of silicon carbide comprises depositing a silicon carbide layer having a thickness ranging from about 1 nanometer to about 3 nanometers.
6. The method of claim 5 , wherein performing an anneal comprises performing an anneal at a process temperature ranging from about 1200 degrees Celsius to about 1400 degrees Celsius.
7. The method of claim 6 , wherein performing an anneal comprises performing an anneal for a duration ranging from about 1 minute to about 30 minutes.
8. The method of claim 1 , wherein recessing the graphene layer is performed using a selective reactive ion etch process.
9. The method of claim 1 , wherein depositing the first shallow trench isolation layer and the second shallow trench isolation layer comprises depositing silicon oxide.