Growing polygonal carbon from photoresist
View Patent ↗A method of growing polygonal carbon from photoresist and resulting structures are disclosed. Embodiments of the invention provide a way to produce polygonal carbon, such as graphene, by energizing semiconductor photoresist. The polygonal carbon can then be used for conductive paths in a finished semiconductor device, to replace the channel layers in MOSFET devices on a silicon carbide base, or any other purpose for which graphene or graphene-like carbon material formed on a substrate is suited. In some embodiments, the photoresist layer forms both the polygonal carbon layer and an amorphous carbon layer over the polygonal carbon layer, and the amorphous carbon layer is removed to leave the polygonal carbon on the substrate.
1. A method of forming a polygonal carbon layer, the method comprising:
providing a photoresist layer on a substrate; and
energizing the photoresist layer until the photoresist layer forms graphene or a graphene-like sheet.
2. The method of claim 1 further comprising removing an amorphous carbon layer formed by the energizing of the photoresist layer to leave the graphene or a graphene-like sheet.
3. The method of claim 2 wherein the energizing of the photoresist layer further comprises one of heating, annealing, performing an ion implantation process on the photoresist layer, and a combination of the forgoing.
4. The method of claim 3 further comprising depositing a metal contact on the substrate to form a semiconductor device in which the graphene or a graphene-like sheet provides a device interconnect.
5. The method of claim 4 wherein the substrate comprises silicon carbide.
6. The method of claim 5 wherein the heating of the photoresist layer further comprises holding a temperature of between about 1200 and about 2000 degrees C. for between about 10 and about 180 minutes.
7. The method of claim 5 wherein the silicon carbide is formed from a zero-degree silicon carbide wafer.
8. The method of claim 7 wherein the heating of the photoresist layer further comprises:
holding a temperature of between about 80 and about 120 degrees C. for between about 10 and about 20 minutes;
holding a temperature of between about 300 and about 700 degrees C. for between about 30 and about 120 minutes; and
holding a temperature of between about 1200 and about 2000 degrees C. for between about 10 and about 180 minutes.
9. The method of claim 3 further comprising:
depositing a gate over at least a portion of the graphene or a graphene-like sheet;
forming a source and a drain adjacent to the at least a portion of the graphene or a graphene-like sheet; and
depositing metal contacts for the source, the drain, and the gate to form a field-effect semiconductor device.
10. The method of claim 9 wherein the substrate comprises silicon carbide.
11. The method of claim 10 wherein the heating of the photoresist layer further comprises holding a temperature of between about 1200 and about 2000 degrees C. for between about 10 and about 180 minutes.
12. The method of claim 10 wherein the silicon carbide is formed from a zero-degree silicon carbide wafer.
13. The method of claim 12 wherein the heating of the photoresist layer further comprises:
holding a temperature of between about 80 and about 120 degrees C. for between about 10 and about 20 minutes;
holding a temperature of between about 300 and about 700 degrees C. for between about 30 and about 120 minutes; and
holding a temperature of between about 1200 and about 2000 degrees C. for between about 10 and about 180 minutes.
14. A method of fabricating a semiconductor structure, the method comprising:
implanting nitrogen into a silicon carbide substrate to form a buried layer of silicon nitride defining a silicon carbide surface layer;
bonding a support substrate to the silicon carbide surface layer;
separating the silicon carbide surface layer from the silicon carbide substrate and the silicon nitride to form a silicon carbide layer bonded to the support substrate;
creating a photoresist layer on the silicon carbide layer;
energizing the photoresist layer until the photoresist layer forms a graphene or graphene-like layer.
15. The method of claim 14 further comprising removing an amorphous carbon layer formed by the energizing of the photoresist layer to leave the graphene or graphene-like layer.
16. The method of claim 15 wherein the energizing of the photoresist layer further comprises one of heating, annealing, performing an ion implantation process on the photoresist layer, and a combination of the forgoing.
17. The method of claim 16 further comprising depositing metal contacts on the silicon carbide layer to form a semiconductor device in which the graphene or graphene-like layer provides device interconnects.
18. The method of claim 17 wherein the heating of the photoresist layer further comprises holding the semiconductor structure at a temperature of between about 1200 and about 2000 degrees C. for between about 10 and about 180 minutes.
19. The method of claim 18 wherein the separating of the silicon carbide surface layer from the silicon carbide substrate and the silicon nitride further comprises contacting the semiconductor structure with phosphoric acid while holding the semiconductor structure at an elevated temperature.
20. The method of claim 16 further comprising:
depositing a gate over at least a portion of the graphene or graphene-like layer;
forming a source and a drain adjacent to the at least a portion of the graphene or graphene-like layer; and
depositing metal contacts for the source, the drain, and the gate to form a field-effect semiconductor device.
21. The method of claim 20 wherein the heating of the photoresist layer further comprises holding the semiconductor structure at a temperature of between about 1200 and about 2000 degrees C. for between about 10 and about 180 minutes.
22. The method of claim 21 wherein the separating of the silicon carbide surface layer from the silicon carbide substrate and the silicon nitride further comprises contacting the semiconductor structure with phosphoric acid while holding the semiconductor structure at an elevated temperature.