An apparatus for generating ultraviolet light and irradiating a 450 mm diameter semi-conductor wafer. The apparatus includes a plenum and an array of nine RF irradiator units coupled with the plenum. Each irradiator unit includes a plasma lamp bulb and an RF generator operable to generate a radiation energy field to excite the plasma lamp bulb and emit the ultraviolet light. The nine irradiator units are arranged in three rows with three of the irradiator units in each row.