Shaped ion blocker plate for indirect ccp

A plasma processing chamber comprising:

• a process chamber body having a bottom wall and at least one sidewall enclosing an interior of the process chamber;
• a gas distribution apparatus forming a top of the process chamber body, the gas distribution apparatus comprising,
• an RF electrode having a front surface,
• an ion blocker plate having a front surface and a back surface defining a thickness of the ion blocker plate, a plurality of apertures extending through the thickness of the ion blocker plate, one or more of the front surface or back surface contoured so that the ion blocker plate has a greater thickness at an outer peripheral region of the ion blocker plate, the back surface of the ion blocker plate spaced a distance from the front surface of the RF electrode,
• an RF isolator between the RF electrode and the ion blocker plate configured to prevent direct electrical contact between the RF electrode and the ion blocker plate, and
• a voltage regulator connected to the ion blocker plate and the RF electrode to polarize one of the ion blocker plate or RF electrode relative to the other of the ion blocker plate or RF electrode;
• and
• a substrate support within the interior of the process chamber, the substrate support having a support surface configured to support a semiconductor wafer for processing, the support surface spaced a distance from the front surface of the ion blocker plate to form a process gap.