Patent ID: 7517710

Claim:
A method of manufacturing of a field emission device comprising: forming a cathode layer on a substrate; forming a first insulating layer on the cathode layer; forming a gate electrode layer on the first insulating layer; forming a protection layer on the gate electrode layer; etching portions of the protection layer and portions of the gate electrode layer, the etched portions of the protection layer and the gate electrode layer forming a plurality of first opening holes, portions of the first insulating layer being exposed through the first opening holes; forming a second insulating layer on the protection layer and on the first opening holes, the second insulating layer filling the first opening holes; forming a focus electrode layer on the second insulating layer; forming a photoresist layer on the focus electrode layer; etching a portion of the photoresist layer and a portion of the focus electrode layer to form a second opening hole where both of the etched portion of the photoresist layer and the etched portion of the focus electrode layer covering the first opening holes, a portion of the second insulating layer being undercut through the second opening hole; undercut etching the exposed portion of the second insulating layer and the portions of the first insulating layer that is exposed through the first opening holes to form emitter holes, portions of the cathode layer being exposed through the emitter holes; removing the photoresist layer; and forming electron emission emitters on the exposed portions of the cathode layer.