Manufacturing of carbon nanotube thin film transistor backplanes and display integration thereof
Methods for producing and integrating single-walled carbon nanotubes (SWCNT) into existing TFT backplane manufacturing lines are provided. In contrast to LTPS and oxide TFT backplanes, SWCNT TFT backplanes exhibit either equivalent or better figures of merit such as high field emission mobility, low temperature fabrication, good stability, uniformity, scalability, flexibility, transparency, mechanical deformability, low voltage and low power, bendability and low cost. Methods and processes for integrating SWCNTs technologies into existing TFT backplane manufacturing lines, pilot test and mass production can start without additional capex needs are also provided.
1. A method for manufacturing a single-walled carbon nanotube thin film transistor backplane comprising:
providing a substrate;
patterning a gate electrode and dielectric layer on the substrate to define a channel region in alignment with the gate electrode;
depositing a back-layer comprised of a thin-film layer of single-walled carbon nanotubes on said dielectric layer; and
patterning at least a n+ layer, and a drain and a source electrode on the back-layer using a photomask and photolithography process such that the n+ layer is in direct contact between the back-layer and the drain and the source electrodes, and such that a portion of the back-layer overlapping the channel region is exposed forming a channel.
2. The method of claim 1 , wherein the back-layer is deposited by a spraying technique selected from the group consisting of aerosol spray, air spray and ultrasonic spray.
3. The method of claim 2 , wherein the single-walled carbon nanotube aerosol is formed from an aqueous solution of single-walled carbon nanotubes that are ultrasonicated in an ultrasonicating nozzle and emitted in a carrier gas flow.
4. The method of claim 1 , wherein the back-layer is printed atop the substrate using aerosol jet printing as a single-walled carbon nanotube aerosol having a deposited linewidth.
5. The method of claim 4 , wherein the single-walled carbon nanotube aerosol is formed by a technique selected from ultrasonic atomization and pneumatic atomization.
6. The method of claim 5 , wherein the deposited linewidth is less than 10 μm with a <2 μm registration accuracy.
7. The method of claim 5 , wherein the aerosol is brought to a spraying head by a carrier gas flow of from 10 to 20 cubic centimeters per minute.
8. The method of claim 1 , wherein the single-walled carbon nanotubes are high purity single chirality single-walled carbon nanotubes.
9. The method of claim 8 , wherein the single-walled carbon nanotubes have an index selected from (6,4), (9,1), (8,3), (6,5), (7,3), (7,5), (10,2), (8,4), (7,6), (9,2), and mixtures thereof.
10. The method of claim 1 , wherein the single-walled carbon nanotube thin film is formed of a plurality of thin films.
11. The method of claim 1 , further comprising depositing and patterning an etch stop layer atop the back-layer such that the etch stop layer overlaps the channel.
12. The method of claim 1 , wherein further comprising treating the single-walled carbon nanotube thin film with acidic gas.
13. The method of claim 12 , wherein the acidic gas is deposited via aerosol spraying.
14. The method of claim 12 , further comprising washing the treated single-walled carbon nanotube thin film.
15. The method of claim 14 , further comprising heating the single-walled carbon nanotube thin film at a temperature of from 60 to 200° C.
16. The method of claim 1 , wherein the thin films are formed with subthreshold leakage current comprising:
spin coating a photoresist on the single-walled carbon nanotube thin film;
defining a pattern atop the photoresist by photolithography to create regions of a defined photoresist and undefined photoresist;
solution developing the defined pattern to form a developed photoresist; and
plasma or wet etching the single-walled carbon nanotubes thin film using the developed photoresist to form a patterned single-walled carbon nanotube thin film.
17. A method for manufacturing a single-walled carbon nanotube thin film transistor backplane comprising:
providing a substrate;
patterning a gate electrode and a dielectric layer on the substrate to form a channel region;
patterning at least an n+ layer, and a drain and a source electrode on the dielectric layer using a photomask and photolithography process such that the portion of the dielectric layer overlapping the channel region is exposed forming a channel;
depositing a back-layer comprised of a thin-film layer of single-walled carbon nanotubes on said n+ layer, drain and source electrodes, and dielectric layer such that the n+ layer is in direct contact between the back-layer and the drain and the source electrodes; and
depositing a passivation layer on the back-layer.
18. The method of claim 17 , wherein the back-layer is deposited by a spraying technique selected from the group consisting of aerosol spray, air spray and ultrasonic spray.
19. The method of claim 17 , wherein the back-layer is printed atop the substrate using aerosol jet printing as a single-walled carbon nanotube aerosol.
20. The method of claim 17 , wherein the single-walled carbon nanotubes are high purity single chirality single-walled carbon nanotubes.
21. The method of claim 20 , wherein the single-walled carbon nanotubes have an index selected from (6,4), (9,1), (8,3), (6,5), (7,3), (7,5), (10,2), (8,4), (7,6), (9,2), and mixtures thereof.
22. The method of either claim 1 or 17 , further comprising integrating the single-walled carbon nanotube thin film transistor backplane into a display device.
23. The method of claim 4 or 19 , wherein the single-walled carbon nanotubes are printed using a plurality of printer heads mounted in association with a moving station, wherein the plurality of printer heads are placed in fluid communication with an aqueous solution of the single-walled carbon nanotubes.