Method and apparatus for processing a semiconductor workpiece

According to the invention there is provided a method of processing a semiconductor workpiece having a front surface and a back surface, including the steps of: i) placing the back surface of the workpiece on a workpiece support in a chamber so that the front surface of the workpiece faces into the chamber for processing, the chamber having an associated chamber gas pressure, and the back surface is in fluid communication with a back region having an associated back gas pressure; ii) performing a workpiece processing step at a first chamber pressure P c1 and a first back pressure P b1 , wherein P c1 and P b1 give rise to a pressure differential, P b1 -P c1 , which is maintained so as to avoid a pressure induced loss of contact between the workpiece and the workpiece support; and iii) performing a workpiece cooling step at a second chamber pressure P c2 and a second back pressure P b2 , wherein P c2 and P b2 are higher than P c1 and P b1 , respectively, at least P b2 being sufficiently high to enhance cooling of the workpiece, and wherein P c2 and P b2 give rise to a pressure differential, P b2 -P c2 , which is maintained so as to avoid a pressure-induced loss of contact between the workpiece and the workpiece support.