Contamination by transition metal impurities is a major concern in Si processing. The bulk contamination tendency is measured as the product of the metal ion diffusivity and its solubility in Si under processing conditions. In particular, iron (Fe) is incorporated as a highly mobile and soluble (Fei+) species. Surface contamination during wafer cleaning is driven by liquid-solid equilibria dictated by the choice of cleaning solution. In Si solid solution Fe is a near-midgap recombination center. Due to its high mobility Fe in solution in p-Si normally exists in the form of an ion-pair with a negatively charged acceptor ion. Gettering, the removal of Fe from active device regions, is accomplished by designing remote regions of lower chemical potential (segregation gettering) or with a high density of heterogeneous nuclei for precipitation (relaxation gettering). This paper presents a comprehensive model for the deposition of Fe from liquid solution, the ion pair structure and stability, and the gettering of Fe from p/p+ epilayers.
|ジャーナル||Materials Science Forum|
|出版ステータス||出版済み - 12 1 1997|
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering