One of the unexplored frontiers in ALD is the enhancement of ALD reactions using non-thermal methods. We are exploring the ability of low energy electrons to enhance ALD reactions. The goal is to reduce the temperature of ALD reactions. Our recent work has concentrated on low temperature GaN ALD using trimethylgallium and ammonia as the reactants. We are also exploring Si ALD using disilane as the reactant.
The electrons serve as one of the reactants in a sequential, self-limiting set of surface reactions. We believe that the electrons stimulate the desorption of hydrogen and generate dangling bonds. These dangling bonds then readily adsorb reactants and facilitate ALD film growth. We have demonstrated crystalline GaN growth at room temperature using this approach. Many other films grown using hydride precursors are also candidates for electron-enhanced ALD.