Plasma and ion beam process-induced damage in semiconductors: review and retrospective

The widespread adoption of plasma and ion beam techniques since the 1980s has led to critical evaluation of the resulting process-induced damage along with developing suitable techniques to passivate or remove the defects. Alternately in some cases the defects are strategically incorporated in device processing to achieve certain ends. Due to the relatively low energies of plasma processes, these defects are mostly confined to the near-surface region of the semiconductor and often have profound influence on the electrical interface with metals as well as insulators. A principal, near-universal phenomenon that is observed under generic ion bombardment in a wide range of commonly used semiconductors - elemental as well as compound - is generation of donor-like defects that reduce surface band bending in n-type material and increase the band bending in p-type. This paper provides a summary overview of the plasma and ion-beam induced defect phenomena, the nature of the defects, their control or removal, the influence of plasma species and thermal history, and their implications in device processing. It also includes a brief historical retrospective on this particular form of defect engineering in the evolution of semiconductor device processing. The focus is mostly on silicon and gallium arsenide, with passing reference to other crystalline semiconductors.