Papers by Author: Alain Moussa

Abstract: Epitaxial growth requires a clean starting surface for the growth of a high-quality crystalline layer. For epitaxy on Si, an HF-last wet clean followed by an in-situ high-temperature hydrogen bake is the reference pre-epi clean sequence to obtain an oxygen-free surface [1, 2]. The temperature required to remove all residual oxygen also makes the surface atoms mobile, resulting in reflow. The high temperatures used during the H₂-bake can also result in intolerable doping profile changes. A lower temperature pre-epi clean sequence is required to avoid this reflow, especially when moving away from Si. In addition the high temperatures needed during a H₂-bake would result in the relaxation of high mobility channels, e.g. strained Si_1-xGe_x or III-V materials [3]. Several low temperatures pre-epi cleaning solutions have been proposed in the past, e.g. GeH₄-assisted H₂-bake [4] or more recently, a GeH₄-assisted HCl clean [5]. In this study we looked at the interaction between HF-last wet clean and the in-situ GeH₄-assisted HCl clean prior to Si_0.8Ge_0.2-on-Si epitaxy.

Abstract: In this work, the compatibility of InP and InGaAs in cleaning solutions commonly used in semiconductor manufacturing is investigated. Aqueous oxidizing cleans should be avoided as the substrates dissolve rapidly. Low pH solutions may impose some serious ES&H issues due to hydride evolution occurring upon acidic hydrolysis of the III-V material. However, acidic solutions are very efficient to remove the native oxide from the substrate. Complete oxide free surfaces are not achieved after wet cleaning due to the rapid oxidation of these materials in the atmosphere.