Fabrication and field emission study of gated DLC-coated silicon tips

The advantage of silicon field emitters is that one can use a VLSI fabrication process, but silicon itself is not a perfect material for use as a field emitter. To improve the material properties of the silicon emitter, we have coated silicon filled emission tips with diamond-like-carbon (DLC) films using PECVD. The DLC film can be formed at low temperature, is flat, and its properties can be controlled with growth condition. First, using a n-type silicon (100) wafer, silicon tips were formed and sharpened using conventional method of reactive ion etching and surface oxidation. To form a gate, a 5000 /spl Aring/ thick oxide layer was formed followed by a 3000 /spl Aring/ thick molybdenum film. Before DLC coating, aluminum was deposited to be used as a parting layer. After this, the oxide caps on the tips were removed. The radius of the silicon tips are 150 /spl Aring/. The DLC was grown on the room temperature surface using PECVD at 20 mTorr pressure. The thickness of the film was 100 /spl Aring/. Finally, the aluminum parting layer was lifted off. The diameter of the gate hole is 1.5 /spl mu/m, and the height of the tips was 0.8 /spl mu/m.