A sputtering source utilizing both microwave and dc planar magnetron plasmas is described. Microwave power is introduced into the plasma by a coaxial‐type cavity. The magnetron target is placed on the open end of the inner conductor. The microwave propagation from the surface of the plasma column produces additional gas ionization, resulting in a denser plasma at constant voltage. The operating pressure of this source is one‐tenth as low as that of a conventional magnetron source. Measured deposition uniformity for Cu is ±4.5% within a 10‐cm diameter at dc 100 W and microwave 800‐W discharge powers for a 15‐cm‐diam magnetron at 6×10−4Torr. The plasma impedance decreases with an increase in the inner conductor diameter and target diameter. The target‐plasma sheath potential can be controlled by microwave power.