Grown-in Defects Modeling of InSb Crystals and Computation
Semiconductor materials are essential for today’s fast growing electro-optic and computer industries and semiconductor crystal growth is a key stage in the manufacturing process. There is constant market pressure to increase the size and quality of crystals so that more and better devices can be put on a single wafer. The most widely used crystal growth technique is the Czochralski (Cz) method, in which a semiconductor crystal is grown at the tip of a seed-crystal while the seed is slowly extracted from a pool of molten material. Crystals grown in this way begin to develop thermal stress defects if the thermal gradients are too large. A trial-and-error approach to process improvement either becomes too expensive or is ineffective. The client, Firebird Technologies, uses the Cz technique to manufacture crystals but an incomplete understanding of the thermal environment during processing was hampering progress. The research team developed a model for the distribution of point defects inside crystals grown by Cz-techniques and developed a series of parameters for optimal crystal growth. Modelling of the processes via mathematical, computational and small-scale experimental methods proved to be an inexpensive and efficient alternative for understanding the fundamental physical processes and improving the manufacturing processes. The team has written a paper on the research results which will be published in Communications on Computational Physics next year in 2006.