Properties of thin films depend strongly upon the deposition technique and conditions chosen. In order to achieve the desired film, optimum deposition conditions have to be found by carrying out experiments in a trial-and error fashion with varying parameters. The data obtained on one growth apparatus are often not transferable to another. This is especially true for film deposition processes using a cold plasma because of our poor under standing of the mechanisms. Relatively precise studies have been carried out on the role that physical effects play in film formation such as sputter deposition. However, there are many open questions regarding processes that involve chemical reactions, for example, reactive sputter deposition or plasma enhanced chemical vapor deposition. Much further research is re quired in order to understand the fundamental deposition processes. A sys tematic collection of basic data, some of which may be readily available in other branches of science, for example, reaction cross sections for gases with energetic electrons, is also required. The need for pfasma deposition techniques is felt strongly in industrial applications because these techniques are superior to traditional thin-film deposition techniques in many ways. In fact, plasma deposition techniques have developed rapidly in the semiconductor and electronics industries. Fields of possible application are still expanding. A reliable plasma reactor with an adequate in situ system for monitoring the deposition conditions and film properties must be developed to improve reproducibility and pro ductivity at the industrial level.