Abstract: A method is for processing a substrate. The method includes placing the substrate in a process volume and introducing a process gas or vapour into the process volume and/or subsequently removing gas or vapour from the volume. The step of introducing and/or removing the gas is at least partially performed by moving a movable wall to change the process volume in an appropriate sense.

Abstract: A method of etching the whole width of a substrate to expose buried features is disclosed. The method includes etching a face of a substrate across its width to achieve substantially uniform removal of material; illuminating the etched face during the etch process; applying edge detection techniques to light reflected or scattered from the face to detect the appearances of buried features; and modifying the etch in response to the detection of the buried feature. An etching apparatus for etching substrate across its width to expose buried is also disclosed.