Fabrication and characterization of singly addressable arrays of polysilicon field-emission cathodes

Polysilicon is a viable candidate material for field-emission microelectron ics devices. It can be competitive for large size, cost-sensitive applicati ons such as flat-panel displays and micro electro-mechanical systems. Singl y addressable arrays of field-emission cells were fabricated in a matrix co nfiguration using a subtractive process on polysilicon-on-insulator substra tes. Matrix rows were fabricated as insulated polycrystalline silicon strip es with sharp emission tips; and matrix columns were deposited as gold thin film electrodes with round gate openings. Ion implantation has been used t o provide the required conductivity of the polysilicon layer. To reduce rad ius of curvature of the polysilicon tips, an oxidation sharpening process w as used. The final device had polysilicon emission tips with end radii smal ler than 15 nm, surrounded by gate apertures of 0.4 tm in diameter. Field e mission properties of the cathodes were measured at a pressure of about 10( -8) Torr, to emulate vacuum conditions available in sealed vacuum microelec tronics devices. It was found that an emission current of I nA appears at a gate voltage of 25 V and can be increased up to I VA at 70 V. Over this ra nge of current, no "semiconductor" deviation from the Fowler-Nordheim equat ion was observed. I-V characteristics measured in cells of a 10 x 10 matrix , with a cell spacing of 50 pm demonstrated reasonable uniformity and repro ducibility. (C) 2001 Elsevier Science Ltd. All rights reserved.