Fabrication of gate holes for field emission array

Aperture of gate hole is an important geometry parameter in a Spindt type field emission array(FEA) cathode. During the local oxidation of silicon(LOCOS) process, a SiO2 “bird beak” will form and lead to much smaller holes than the Si3N4 dot patterned by lithography. By means of LOCOS and wet etching of the silicon substrate, gate of FEA with 1 μm aperture was fabricated using a photo mask of 2.6 μmdot (designed) array. The etchant composed of nitric acid (65%) and hydrofluoric acid (40%) isotropicly etched the silicon material, resulting in simultaneous growth the depth and width of gate holes. However, the hole aperture gradually enlarged at a rate only 5% of that of the development of the depth. The ultimate hole aperture principally defined by the photo mask size and the thicknes