A wafer processing apparatus includes a processing chamber having a top chamber portion and a bottom chamber portion, respectively. The apparatus further includes an annular ring valve associated with one of the top chamber portion and the bottom chamber portion which is operable to close the processing chamber for processing in a first position and open the processing chamber for access thereto in a second position. The ring valve, in the first position, provides a substantially uniform surface about an inner periphery of the closed processing chamber, and thereby facilitates uniform processing conditions. A method of accessing a wafer processing apparatus is also disclosed and includes moving an annular ring valve within a processing chamber between two positions. In the first position the annular ring valve sealingly blocks an access port of the processing chamber and thereby prohibits access thereto, and in the second position the annular ring valve does not block the access port, and permits access to the processing chamber. The annular ring valve has a substantially uniform inner peripheral surface, and thereby facilitates uniform processing conditions within the processing chamber when in the first position.