سال انتشار: ۱۳۹۱
محل انتشار: کنفرانس بین المللی مدل سازی غیر خطی و بهینه سازی
تعداد صفحات: ۷
Mehdi Darbandi – Department of Electrical Engineering and Computer Science at Iran University of Science and Technology (IUST
Mohammad Abedi –
Real crystals differ from the ideal in that they possess imperfections or defects . Some defects, due to impurity dopant atoms, are absolutely necessary forcreating devices in the crystal. Other crystalline defects may be helpful if present in moderate density. Most however are undesirable, regardless of the density inwhich they may be found in the crystal. Various forms of defects in single-crystal and their structures, mechanisms of theirformation are described by, S. Wolf and R. N. Tauber, in great detail . Unwanted crystalline defects and impurities can beintroduced during silicon crystal growth orsubsequent wafer fabrication processes. These defects and impurities, some are undesirable because both can degrade devicecharacteristics and overall yield. Gettering is the process whereby impurity concentrations are reduced in the device region of the waferby localizing them in separate, predefined regions of the wafer where they cannot affect device performance. The managementof metal contamination is one of the mostimportant aspects of successful integrated circuit manufacture. Gettering has long been an important part of the silicon fabrication process. Simply, gettering is a stand-by process whereby metal contamination is rendered harmless in the event of a failure ofprocess contamination control. This article covers some of the fundamental principles that underlie this very important technology and discusses various approaches to the problem, highlighting the issues associated with each of them.