PROGRAMMABLE DRAWING FROM MELT OF UNIFORMLY ALLOYED SINGLE CRYSTALS OF SILICON

摘要

Production of uniformly alloyed single crystals from semiconducting materials using a technique based on programmable control of growth parameters (first of all, of th drawing rate) has been among the first methods of homogenization of they crystal's impurity composition (1). Since the appearance of the first reports on the subject (1,3), this process was studied in finest detail (4-7).However, despite the obvious success of the technique, in practice it has been used only to grow germanium single crystals. The reason is that germanium is the only material for which experimental dependences of the effective impurity-distribution coefficients are available (knowledge of these dependences is essential in writing and implementing a program). There is an opinion that this, in its turn, can be explained by specific characteristics of the system germanium - impurity. In the case of, for example, silicon, the high volatility of impurities, as well as the - probably - weak dependence of the effective impurity distribution on growth condition, would make it impossible to implement similar equalization schemes. It was only in the 1960s that the whole set of data needed for programming of alloyed silicon were published by Kodera (8).