Sub-atmospheric pressure plasmas play a critical role in semiconductor device processing. Plasmas provide the ions used to sputter surfaces, modify film properties and affect the surface coverage by deposited films. Plasmas also 3activate2 reactive species to enhance chemical reactivity for reactive cleaning, deposition and etching processes. This paper reviews the history of using plasmas for surface preparation, PVD and PECVD film deposition, modification of film properties, reactive deposition and plasma etching to create film structures.