Plasma processing in microelectronics manufacturing

Plasma processing has emerged as an important technology for the deposition and etching of thin solid films in the manufacture of microelectronic devices. In fact, much of the progress achieved to date in device miniaturization would have been much more difficult without the unique characteristics of plasma processes. It is anticipated that future progress will continue to rely heavily on plasma technology. Although plasma chemical reactors are widely used, a lack of fundamental understanding has resulted in heavy reliance on empiricism in process design and control. The complexities inherent in any chemical reactor are compounded in plasma processing by the presence and active participation of the discharge in both gas phase and surface chemical processes. This has resulted in a technology that is sensitive to many design and operating parameters. A large parameter space gives process engineers flexibility in tailoring process conditions to meet objectives. However, without fundamental insight into the key physical and chemical processes, reactor design and control cannot be based on systematic, rational procedures. The purposes of this review are to introduce chemical engineers to plasma processing practice and phenomenology; to outline the progress made to date in fundamental studies of discharge physics and chemistry; to indicate areas in which chemical engineers must expand their traditional training to participate in plasma processing research; and finally to suggest how established chemical engineering methodology can be applied to plasma chemical reactors.