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 Å thick oxide layer was formed followed by a 3000 Å 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 Å. The DLC was grown on the room temperature surface using PECVD at 20 mTorr pressure. The thickness of the film was 100 Å. Finally, the aluminum parting layer was lifted off. The diameter of the gate hole is 1.5 μm, and the height of the tips was 0.8 μm