Control of substrate temperature (T-S) during plasma etching and film deposition using fluorinated silicon gases has -profound effects on etch and deposition rates as well as the overall composition of deposited materials. How T-S directly affects individual species and reactions at the plasma-surface interface, however, is not fully understood. Using the imaging of radicals interacting with surfaces technique, we have measured the effect of T-S on SiF and SiF2 surface reactivity in SiF4 and SiF4:H-2 plasmas under a variety of plasma conditions. At T-S = 300 K, there is significantly more SiF2 than SiF emanating from the surface. This is expected as SiF2 is a known etch product. Interestingly, higher substrate temperatures result in significant increases in surface scatter for both molecules. These results are discussed with respect to the role that each molecule plays in etching and deposition mechanisms, as well as in comparison to results for plasma species in other plasma systems. In addition to surface interaction measurements, rotational temperatures (theta(R)) for SiF and SiF2 were measured in a 170 W plasma as 450 +/- 50 and 752 +/- 100 K, respectively. (C) 2003 American Vacuum Society.