A tunable upper plasma exclusion zone (PEZ) ring adjusts a distance of plasma during processing in a processing chamber and includes: a lower surface that includes: a horizontal portion; and an upwardly tapered outer portion that is conical and that extends outwardly and upwardly from the horizontal portion at an upward taper angle of about 5° to 50° with respect to the horizontal portion, where an outer diameter of the upwardly tapered outer portion is greater than 300 millimeters (mm), and where an inner diameter where the upwardly tapered outer portion begins to extend upwardly is less than 300 mm. A controller is to, during processing of a 300 mm circular substrate, adjust the distance of plasma for treatment of the 300 mm circular substrate at least one of radially inward and radially outward using the tunable upper PEZ ring.