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 °C for 1 h. The devices treated at 350 °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 cm2·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.