Methods and apparatus for processing substrates are provided herein. In some embodiments, a shroud for controlling gas flow in a process chamber includes a closed walled body having an upper end and a lower end, the closed walled body defining a first opening of the shroud at the lower end and a second opening of the shroud at the upper end, wherein the second opening is offset from the first opening; and a top wall disposed atop a portion of the upper end of the closed walled body in a position above the first opening to define, together with a remaining portion of the upper end of the closed walled body, the second opening, wherein the shroud is configured to divert a gas flow from the second opening through the first opening.