Pulsed DC power for deposition of film

A method of depositing a dielectric film in a high aspect ratio feature of a semiconductor substrate, the method comprising:

• applying power to a dielectric target within a vacuum chamber to generate a plasma in a process gap between the dielectric target and a substrate support, the power being a pulsed DC power having pulsed DC waveform, the pulsed DC waveform comprising a plurality of ON pulses and a plurality of OFF pulses, each of the ON pulses and the OFF pulses independently being in a range of from 1 μs to 50 μs, a voltage of the plurality of ON pulses being in a range of from greater than 9 V to 1500V, the pulsed DC waveform being generated at a frequency in a range of from 10 KHz to 500 kHz, and the pulsed DC waveform having a duty cycle in a range of from greater than 0 to less than 0.6;
• pulsing the power applied to the dielectric target to prevent charge accumulation;
• and
• applying a reverse bias to the substrate support using a reverse bias source, wherein the reverse bias source is AC power, DC power, or RF power, and wherein the reverse bias source is not pulsed,
• the high aspect ratio feature having a height:width ratio greater than or equal to 10:1.