Investigation of Aluminum Metallized Source/Drain Thin Film Transistors Using a Self-Aligned Fabrication Process

Abstract

For a better thin film transistor performance, metal silicide has been studied in order to enhance the conductivity of the source and drain electrodes. Although aluminum does not form a metal silicide with silicon, the two materials interpenetrate in an induced crystallization process. In such a structure, aluminum can act as a p-type dopant in the silicon lattice. In this work, aluminum metallized source/drain thin film transistors with excimer laser-annealed polycrystalline silicon were fabricated using a simple self-aligned process. The source/drain regions were patterned with a lift-off process. The n-channel characteristics of the as-deposited aluminum source/drain were explored and an improvement in the performance was observed after a heat treatment at 250 degrees C for 1 h. The devices treated at 350 degrees C for 10 h exhibited p-channel characteristics. The device characteristics were compared with another fabricated p-type doped source/drain structure. A remarkable enhancement in the performance of the aluminum metallized source/drain devices was observed. These structures yielded a peak field effect mobility of about 105 cm(2).V(-1).s(-1). The simple fabrication process and resulting enhancement in device performance makes this type of structure ideal for use in thin film transistors on glass. (C) 2010 The Japan Society of Applied Physics