a bevel in the clamping ring is provided near its inner circumference to define a hood 18 which overhangs and covers the outer periphery of the wafer 10 around the latter 39 s entire circumference the hood 18 effectively shadows the outer periphery of the wafer 10 and tends to protect the outer clamping surface 26 of the clamping ring 16 from being coated by the deposited material without the hood 18 an inordinant amount of material would be deposited near the periphery of the wafer 10 which in turn would tend to weld the wafer 10 to the clamping ring 16 when welding occurs between the clamping ring 16 and the wafer 10 severe contamination by particles occurs when the wafer 10 is broken from the clamping ring 16 thereby leading to lower yields of wafer production notwithstanding the use of the hood 18 some amounts of the deposited material is shown by the numeral 28 and fig2 may nevertheless occur which are contiguous to and tend to bond the clamping ring 16 and the wafer 10 the problem of the wafer sticking to the clamp is even more severe in certain types of processes where substantial amounts of deposited materials contact both the wafer and the clamp for example referring now to fig3 5 in the case of an ion implantation process a layer of photoresist 30 is applied to the surface of a wafer 10 which is later etched away leaving a ring shaped layer 30 of photoresist which is clamped directly between the clamping surface of the clamping ring 16 and the wafer 10 in fig4 it can be seen that the ring shaped clamp 30 overlies the wafer 10 with the amount.