Process and electrical characteristics of MO-ALD HfO2 films for high-K gate applications grown in a production-worthy 300 mm deposition system
Abstract
In this work, we present a study of the growth and electrical characteristics of metalorganic atomic layer deposited (MO-ALD) HfO2 films deposited using a 300 mm Counter-Flow ALD platform. HfO2 films were deposited over a large range of process temperatures, and flow rates in order to fully characterize the MO-ALD process window. The HfO2 films were characterized using AFM, HRTEM, MEIS, and SIMS. Saturation curves were generated for precursor and ozone oxidant over a 150 °C process temperature window, using two different flow rates of Hf precursor. The use of water versus ozone as an oxidant was also investigated. Since all depositions take place above the decomposition temperature of the precursor, it is critical to understand and control the rate of thermal decomposition or parasitic CVD in the process in order to realize good uniformity in a traveling wave-type system. Thus, we have measured the rate of thermal CVD over the full range of temperatures. The thermal CVD rate shows a concave Arrhenius behavior as the process rises in temperature and transitions from an ALD dominated growth mechanism to a CVD dominated mechanism. We propose a possible explanation for this behavior. In addition to the growth characteristics, we have investigated the electrical properties of the as-deposited films using in-line Quantox measurements, and gate stack structures using integrated devices. The relationship between process and electrical characteristics will be discussed. © The Electrochemical Society.