Fabrication of carbon-nanotube field-emitter array using polymer insulator

Abstract

This article reports the fabrication process of a carbon-nanotube (CNT) field-emitter array with the silicon-ladder polymer insulator polyphenylsilsesquioxane (PPSQ), whose feature is heat resistance, high breakdown voltage, and low outgassing. CNT islands are formed with a screen-printing method, polymer-insulator coating is carried out (8 μm in thickness), and the gate electrodes are deposited, followed by patterning of the electrodes. PPSQ insulator is applied reactive ion etching (RIE) to reveal CNT emitters. Because of using mixed gases of CF4 and O2, the etching rate for CNT is half that for PPSQ, there is a margin to stop etching with enough CNT left. After reactive ion etching, emission-current density from the revealed CNT is degraded, so laser activation treatment is applied and the emission current density is boosted by a hundredfold. In the case of the triode mode, the laser condition was chosen to prevent gate damage and to improve emission characteristics. Current density of 3 mA/cm2 is obtained at the driving voltage of 35 V.