Modeling and Optimization for Epitaxial Growth: Transport and Growth Studies

This report details the objectives, methodologies, and results for Phase II of the project, “Modeling and Optimization for Epitaxial Growth” (see [21] for Phase I report). This project is a joint effort between the Institute for Systems Research (ISR) and Northrop Grumman Corporation’s Electronic Sensors and Systems Sector (ESSS), Baltimore, MD. The overall objective is to improve manufacturing effectiveness for epitaxial growth of silicon and silicon-germanium (Si-Ge) thin films on a silicon wafer. Growth takes place in the ASM Epsilon-1 chemical vapor deposition (CVD) reactor, a production tool currently in use at ESSS. Phase II project results include development of a new comprehensive process-equipment model capable of predicting gas flow, heat transfer, species transport, and chemical mechanisms in the reactor under a variety of process conditions and equipment settings. Applications of the model include prediction and control of deposition rate and thickness uniformity; studying sensitivity of deposition rate to process settings such as temperature, pressure, and flow rates; and reducing the use of consumables via purge flow optimization. The implications of various simulation results are discussed in terms of how they can be used to reduce costs and improve product quality, e.g., thickness uniformity of thin films. We demonstrate that achieving deposition uniformity requires some degree of temperature non-uniformity to compensate for the effects of other phenomena such as reactant depletion, gas heating and gas phase reactions, thermal diffusion of species, and flow patterns. This research was supported by grants from the Northrop Grumman Foundation, the National Science Foundation’s Engineering Research Centers Program: NSFD CDR 8803012 and NSF Grant EEC-9527576, and the Army Research Office under the ODDR&E MURI97 Program Grant No. DAAG55-97-1-0114.