Semiconductor processing system and methods using capacitively coupled plasma

A substrate processing system comprising:

• a gas inlet for supplying a first gas to a processing chamber;
• a remote plasma unit coupled with the gas inlet and configured to provide radical precursor species to the chamber;
• a showerhead having a first plurality of openings, wherein each opening of the first plurality of openings is characterized by a length extending through the showerhead, and wherein each opening of the first plurality of openings tapers in diameter from the upper surface of the showerhead at least partially along the length of the respective opening;
• an activation region inside the processing chamber to excite the first gas into an activated gas, wherein the activation region is defined between:
• an electrode comprising at least one opening;
• and
• an ion suppressor plate located above the showerhead and comprising an electrically conductive plate having a second plurality of openings to permit passage of the activated gas, wherein the ion suppressor plate divides the activation region into an upper region and a lower region, wherein the lower region is defined between a lower surface of the ion suppressor plate and an upper surface of the showerhead, wherein
• each opening of the second plurality of openings is characterized by a length extending through the ion suppressor plate, wherein each opening of the second plurality of openings tapers in diameter from the lower surface of the ion suppressor plate at least partially along the length of the respective opening, and wherein the taper in diameter of each opening of the second plurality of openings is characterized by a taper angle between about 15° and about 30° to at least partially prevent plasma particles generated below the ion suppressor plate from flowing up through the second plurality of openings;
• a reaction region defined between the showerhead and a substrate;
• and
• an electrical power supply coupled with the ion suppressor and the showerhead, wherein the electrical power supply is configured to produce a plasma in the lower region of the activation region.