Thin YBa2Cu3O7-x superconducting films have been grown by several sputtering techniques including single target rf glow discharge sputtering, multi-target rf sputtering, ion beam sputtering, and rf magnetron sputtering. A variety of substrates were used for the deposition and the best superconducting properties were obtained on single crystal (100) MgO and (100) SrTiO3 substrates. RF sputtering was studied in detail because some very unique effects were observed during the sputtering. These effects, i.e., substrate heating, resputtering and stoichiometric deposition, were investigated. Substrate heating was found to be mainly due to secondary electron impingement. Resputtering may be mostly due to energetic neutral particle bombardment; however, negative ion bombardment cannot be ruled out. Ba deficiency in substoichiometric films may be due to the formation of Ba+ ion formation and recapture by the cathode and due to intense substrate heating. Films grown by rf diode sputtering had to be compensated with excess Ba to maintain stoichiometry.