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METHOD TO EVALUATE THE EFFECT OF THIN FILM MATERIALS ON THE LIFETIME OF FIELD EMISSION CATHODE ARRAYS

IP.com Disclosure Number: IPCOM000004631D
Original Publication Date: 2001-Mar-01
Included in the Prior Art Database: 2001-Mar-01
Document File: 2 page(s) / 27K

Publishing Venue

Motorola

Related People

Babu R. Chalamala: AUTHOR [+2]

Abstract

A simple method for the evaluation of materials suitable for the fabrication of field emission displays is presented. The technique is based on the sensitivity of a large field emitter array to the outgassing or desorption of gas species from thin films under electron beam excitation. We demonstrate the usefulness of the technique for the evaluation of thin film materials suitable for use with Mo field emitter arrays.

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METHOD TO EVALUATE THE EFFECT OF THIN FILM MATERIALS ON THE LIFETIME OF FIELD EMISSION CATHODE ARRAYS

Babu R. Chalamala and Robert H. Reuss

ABSTRACT

A simple method for the evaluation of materials suitable for the fabrication of field emission displays is presented. The technique is based on the sensitivity of a large field emitter array to the outgassing or desorption of gas species from thin films under electron beam excitation. We demonstrate the usefulness of the technique for the evaluation of thin film materials suitable for use with Mo field emitter arrays.

INTRODUCTION

Field emission displays (FEDs) are an area with immense commercial promise as high brightness light weight flat panel displays.1 Field emission displays are similar to cathode ray tubes in that light is generated by the electron beam excitation of inorganic phosphors. In these devices, even though the electron beam is directed to the phosphor screen, a small percentage of electrons do bombard other parts of the display including dielectric materials on the anode surface, dielectrics and other electron beam sensitive materials on the field emitter array (FEA), ceramic spacers and vacuum gettering materials. In the case of phosphors, electron beam bombardment is done by design, but electron impact on other parts of the display occurs inadvertently. It is evident from published literature that FEAs made from Mo, Nb and Si are prone to oxidation in the presence of oxygenic gases.2,3 Electron bombardment of various materials has been shown to result in the desorption of gases from their surfaces.4 Outgassing of gases from thin film surfaces under electron bombardment can result from many different processes, including thermal desorption, chemical decomposition of thin films, and electron stimulated surface reactions. However, very little information has been published showing how such processes actually impact FED performance under operational conditions. To minimize the potential for materials degradation under electron bombardment and to limit resulting increase in package pressure, a simple and reliable means to identify thin film materials that have minimal impact on device performance is needed. A sensitive means to detect the impact of desorption from various materials on the emission characteristics of a field emitter array is needed.

EXPERIMENTAL METHOD

Field emitter arrays that are used in FEDs contain millions of individual emitter cones. Such a large emitter array can be used as a high sensitivity detector to determine the effects of desorption from various thin films. The method provides an extremely sensitive measure of outgassing because of the well documented sensitivity of emission current to contamination sources. The field emitter array is used as both the electron source and gas detector. The material under test is coated onto an "inert" anode (Stainless steel plate, 1 mm thick) support. The thickness of the film is such 200 Å) that charge can bleed off vertically to...