Gettering and passivation of metals in silicon and germanium

Abstract

The aim of this chapter is surely not to review all the different gettering approaches that have been reported in the literature, but rather to give a type of synopsis and to focus on the understanding and the new insights that have been obtained since the beginning of the century. First some general aspects about gettering strategies are discussed, giving a schematic overview of different gettering approaches, before outlining the main gettering mechanisms. At the same time the nomenclature used in the gettering world is explained. Of key importance is the difference between segregation gettering and relaxation gettering. Subsequently the different backside gettering techniques are reviewed, including backside damage, thin layer depositions and ion implantation. New insights related to the phosphorus diffusion gettering will be outlined. Intrinsic gettering in Cz-Si substrates based on oxygen precipitates will be discussed next. For state-of-the-art low-thermal-budget CMOS front-side gettering techniques gain more and more momentum, as will be described in a next section. The two following paragraphs are dealing with gettering in Silicon-on-Insulator technologies and photovoltaics, respectively. The last paragraph gives some reflections on ab initio calculations and continuum modeling for gettering, a topic that is discussed in more detail in Chap. 9.