Lasers solutions for wafer and thin‐film annealing

Abstract

AbstractThe application of lasers for the annealing of wafer‐based and thin‐film microelectronic devices is steadily increasing. Excellent control of material characteristics (for example, dopant activation profile) can be achieved through proper selection of laser parameters, such as wavelength, pulse duration and fluence. In this paper, we present recent results achieved with our industrial lasers and tailored optical systems used for annealing and activation. Such systems include Excimer Lasers, q‐switched DPSS Lasers and our unique high‐power CW laser system that delivers scalable output power of multiple hundreds of Watts in the visible wavelength range. One focus is the formation of ultra‐shallow Source/Drain junctions for CMOS nodes below 90 nm. We will present results from Excimer Laser Annealing (ELA) that show high dopant activation, exact control over the junction depth and efficient implant damage removal. Another application is power MOSFET, where a laser source is utilized for dopant activation and damage healing over micron depths. The choice of wavelength (i.e. green) with adequate interaction time leads to an optimized activation profile. The use of single laser pulses, pulse trains or continuous irradiation leads to the preferred annealing result. Crystallization of thin films is another large domain for laser annealing equipment. We will present selected results from silicon thin‐film annealing, which is commonly used in the Flat Panel Display industry. The applicability of these technologies beyond displays into electronics and photo‐voltaic applications is also shown. In addition, descriptions are provided of experimental results and simulations of laser sources and optical systems that enable variation of the temperature profile within the irradiated materials and offer the scalability and maturity as demanded by the semiconductor industry. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)