Effect of hydrogen dilution on the structure of SiOF films prepared by remote plasma enhanced chemical vapor deposition from SiF4-based plasmas

Structural and electrical properties of fluorinated silicon dioxide (SiOF) films prepared by remote plasma enhanced chemical vapor deposition from the SiF4-O-2-H-2-He gas mixture have been studied using ellipsometry, Fourier transform infrared spectroscopy, transmission electron microscopy, and curr ent-voltage measurements. It has been found that the level of hydrogen dilu tion strongly affects the microstructure of deposited SiOF films. The films prepared at the H-2 flow rate below about 0.8 seem have a biphase structur e consisting of an amorphous matrix with the incorporation of 5-30 nm sized particles. The main origin of these particles seems to be gas phase oxidat ion of SiFx species (with x = 1, 2, 3) in plasma and downstream regions. Re sulting films are characterized by extremely low density, reduced structura l homogeneity, and poor electrical properties. Increase in the H-2 how rate above 0.8 seem completely suppresses the incorporation of particles into t he growing film probably due to effective hindering gas phase oxidation pro cess and results in dense homogeneous amorphous SiOF films with good electr ical properties. (C) 2000 American Vacuum Society. [S0734-2101(00)01506-8].