Diagnostics of a chemically active, pulsed microwave plasma for depositionof quartz-like films

A remote microwave plasma has been used for the deposition of scratch-resis tant quartz-like films. Process gases are argon, oxygen, and hexamethyl-dis iloxane. Input power is modulated and the effects on the plasma as well as on the deposition process are studied by means of various diagnostic method s. The film deposition rate is slightly reduced under most conditions but f ilm quality (i.e., cluster size, roughness, scratch resistance) may be impr oved. A precursor has been identified by mass spectrometric measurements. I ts relation to volatile oxides is discussed. The atomic oxygen density and the electron density are determined temporally-resolved. By a suitable choi ce of the pulse frequency the time-averaged densities of both species can b e significantly enhanced as compared to the continuous case. Consideration of the plasma power balance explains how electron density and temperature a re influenced by pulsing. It is concluded that the optimum pulse frequency has to be matched to the electron loss rate which mainly depends on the geo metrical dimensions of the process chamber.