A NEW FABRICATION TECHNOLOGY FOR FIELD-EMISSION TRIODES WITH EMITTER-GATE SEPARATION OF 0.18-MU-M

A new fabrication technology has been used for field-emission triodes with the emitter-gate separation as small as 0.18 mum to reduce the tu rn-on and anode voltages. The technology is based on the thermal oxida tion of silicon and low-pressure chemical vapor deposition (LPCVD) of polycrystalline silicon, making the fabrication of a sub-half-micronme ter gate opening easy and reproducible. The entire process requires us e of only one photolithography mask, and does not require advanced hig h-resolution photolithographic techniques. In this device, the oxidati on process serves the three purposes of sharpening the emitters, defin ing the emitter-gate separation, and achieving a high-quality insulato r. The finished devices have the emitter situated exactly at the cente r of the gate opening due to a self-alignment process. Furthermore, th e LPCVD polysilicon film can form gate electrodes with a smooth edge a nd a small gate opening due to excellent step coverage.