Hironori Imura

A Super Steep Mo Tip Fea Fabrication And Emission Characteristics

A super steep 4 nm radius MO tip field emitter array (called Spindt type cathode(’)) with excellent electron emission characteristics has been obtained by an evaporation rate optimization(shown in Fig.1 and 2). For achieving the uniformity in the emission current as well as in the microscopic structure, the standard processes and advanced equipments, specially developed for 64 M bits DRAM through hole manufacturing process has been utilized. Especially, in lithography process, 5 1 stepper with an i-line ultra violet light exposure was introduced, which enable the direct gate aperture fabrication. Further, the special treatment to keep out Erom contamination guarantees the constant excellent emitter fabrication. Less than 40 volts is required for the threshold voltage to observed the emission currents(shown in Fig.3). The emission data is well explained by the Fowler-Noldheim equation. The gate aperture diameter, the WSi gate layer thickness, the insulator thickness and tip number are 0.9 pm, 0.2 p, 0.48 pn and 11 3 tips respectively. In this presentation, the characteristics for the more advanced emitter array with less than 0.5 pm wide gate aperture and 1.5 pn tip separation will be shown. (The gate perspective view is shown in Fig.4.) The sharper tips, the smaller aperture diameter size and higher tip packaging density will make the FEA working threshold voltage lower and increase the emission current density. Moreover, the life time will be elongated to endure normal usage. Thus, the FEA is expected to exceed the thermal cathode capability.