Patent ID: 9117767
Filing Date: 2015-08-25
Classification: C23C,H01J,H01L,H05H

Abstract:
1. A capacitively-coupled plasma chamber, comprising: a bottom radio frequency (RF) signal generator coupled to a bottom electrode, the bottom RF signal set at a first frequency at a first phase; a top RF signal generator coupled to a top electrode, the top RF signal set at the first frequency at a second phase, the top electrode being at a predetermined distance from the bottom electrode; and an RF phase controller configured to determine the first phase of the bottom RF signal and configured to calculate a predetermined value as a travel time required for negative ions formed near a top plasma sheath of the plasma to travel the predetermined distance towards the bottom electrode, wherein the RF phase controller is further configured to set a value of the second phase of the top RF signal generator based on the predetermined value, wherein the RF phase controller is configured to set the second phase to maintain a time difference between a maximum of the top RF signal and a minimum of the bottom RF signal at approximately the predetermined value.