Published online by Cambridge University Press: 15 March 2011
The IGAM engineering company for applied mechanics Ltd. developed an active piezocontrolled carrier for CMP. It uses several, by means of piezo-stacks individually controllable rings. The carrier is optimized regarding its stiffness and reliability by means of threedimensional finite element calculations. The high stiffness and positioning accuracy of the system allows the exact control of different surface profiles and thus the purposeful attitude of the pressure and removal profile independently of the polishing pressure. Tests show a very homogeneous pressure and removal distribution in the circumference of the wafer. The concept is transferable on further wafer diameters, whereby the width of the individual zones can be widely adapted to the requirements of the desired removal profile. Results of finite element analysis for a 12” prototype are available. The variable concept allows to upgrade existing CMP machines. The aims of current developments are the integration of in-situ-pressure determination to control the process, wireless transfer of energy and data to the carrier and the control of the local removal profile.