7.4 Depositing compounds
As well as conducting metal layers, device fabrication requires dielectric, insulating materials and these are mostly chemical compounds rather than simple elements or alloys. By far the most widely used of these is silicon oxide (either as a glass or as crystalline quartz), but other oxides and nitrides are also common, plus polymers and a selection of more exotic materials.
Such compounds generally have very high melting points, or decompose under heating, so cannot be deposited by evaporation. As they are electrically insulating electroplating is out of the question, and a target made from insulating material cannot carry a current to drive DC sputtering. An entirely separate set of deposition techniques is therefore required.