A high-pressure processing system for processing a substrate includes a first chamber, a pedestal positioned within the first chamber to support the substrate, a second chamber adjacent the first chamber, a vacuum processing system configured to lower a pressure within the second chamber to near vacuum, a valve assembly between the first chamber and the second chamber to isolate the pressure within the first chamber from the pressure within the second chamber, and a gas delivery system configured to introduce a processing gas into the first chamber and to increase the pressure within the first chamber to at least 10 atmospheres while the processing gas is in the first chamber and while the first chamber is isolated from the second chamber.