Peelable photoresist for carbon nanotube cathode
A method for forming a field emission cathode device is disclosed using a peelable photoresist with standard photolithography processes for patterning a deposition mask, except that the peelable photoresist can be peeled away in dry form. The method offers standard photoresist accuracy with the advantage of high patterning resolution for producing carbon nanotube (CNT) field emitter displays. Example methods using a single peelable photoresist layer, and using two distinct layers of photoresist and peelable film, are presented. Since the method does not require wet processes after CNT deposition, it ensures enhanced CNT emitter performance. In addition, an activation process that liberates CNTs can be performed just before a tape lamination and peeling process step. In this manner, all superfluous nanoparticle material remains confined between the tape and photoresist films, which are removed together and properly discarded.
1 . A method for forming a field emission cathode device, comprising a plurality of cathode structures, comprising the steps of:
forming a conducting film comprising a plurality of feed lines and electrode pads on a substrate using a conducting material;
forming an insulating film comprising a plurality of barrier ribs and insulating pads on said substrate and said conducting film using an insulating material;
coating said substrate, said conducting film, and said insulating film with a layer of peelable photoresist; and
exposing and developing said peelable photoresist using standard photolithography processes to generate a mask pattern in said peelable photoresist which unmasks a plurality of electrode pads.
2 . The method as recited in claim 1 , further comprising the step of:
coating a composite structure of said substrate, said conducting film, said insulating film, and said mask pattern in said peelable photoresist with a layer of nanoparticle ink, such that a layer of nanoparticle ink is deposited on the masked portions and the plurality of unmasked portions of said peelable photoresist.
3 . The method of claim 2 , wherein said nanoparticle ink contains carbon nanotubes (CNTs).
4 . The method as recited in claim 2 , further comprising the step of:
activating said layer of nanoparticle ink for field emission of cathode rays by implanting nanoparticles onto a surface of said layer of nanoparticle ink, particularly activating thereby said plurality of unmasked portions of said peelable photoresist coated with said nanoparticle ink.
5 . The method as recited in claim 2 , further comprising the step of:
laminating with an adhesive tape the composite structure of said substrate, said conducting film, said insulating film, said mask pattern in said peelable layer, and the layer of nanoparticle ink in contact with said peelable layer, such that only the nanoparticle ink layer deposited on the masked portions of said peelable layer is contacted with said adhesive tape;
6 . The method as recited in claim 5 , further comprising the step of:
detaching said adhesive tape from said composite structure, such that said adhesive tape, the nanoparticle ink in contact with said adhesive tape and said peelable layer, and said peelable layer are removed together.
7 . The method of claim 1 , wherein said peelable photoresist comprises:
a first applied layer of peelable material; and
a second applied layer of photoresistive material, such that both first and second applied layers are completely and identically removed from the unmasked regions of said mask pattern generated upon said exposing and said developing using standard photolithography processes.