Abstract: An apparatus for providing active cooling for semiconductor wafers during implantation in an ion implantation chamber includes a housing incorporating a convexly curved platen. The platen has a coating of a pliable thermally conductive material adhered to the surface thereof. A clamping ring is mounted within the housing in slidable relationship with the convexly curved platen so that the travel of the clamping ring ranges between a receiving position wherein the clamping ring and the convexly curved platen define a slot for receiving a semiconductor wafer and a locked position wherein a semiconductor wafer is firmly pressed against the convexly curved platen by the contact of the clamping ring against the semiconductor wafer at its circumferential edge. In the locked position the wafer substantially conforms on its back side to the contour of the convexly curved platen. An active cooling means is provided for transferring thermal energy away from the platen.