TABLE OF CONTENTS Stephen Rossnagel
Sputtering and sputter deposition are widely used techniques for the erosion of surfaces and the deposition of films. Sputtering, also known as sputter etching, is used for patterning semiconductor wafers, for cleaning surfaces, for micromachining, depth profiling, and a number of applications which require careful, microscopic erosion of a surface. Sputter deposition is used for film deposition on semiconductor wafers, on magnetic media and head surfaces, for coating tools and cutting surfaces for wear resistance (this includes, by the way, such tools as shaving razors), for reflective coatings on window glass, for coating the insides of plastic bags and the surfaces of automobile parts, and a number of other wide ranging applications.
Sputtering is usually practiced by means of plasmas which generate charged particles which can be accelerated towards a surface electrically. Sputtering is simply the process of erosion of that surface by the energetic particles, a sort of atomistic sandblasting. Sputter deposition is nothing more than the accumulation of these atoms which are blasted off the surface onto a nearby sample. For the most part, this chapter deals with sputtering and sputter deposition with a slant towards semiconductor processing. However, the discussion is wide enough that other areas are introduced from time to time as needed.
Sputtering occurs whenever any particle strikes a surface with enough energy to dislodge an atom from the surface. The sputter yield is just the ratio of the number of emitted particles per incident particle:
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