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Analysis and Performance of a lightweight over-actuated 450mm wafer chuck R. Boshuisen, PME 09-06-2010 Rein Boshuisen, PME Titel van de presentatie 1 Contents • Introduction • Problem Description • Principle of Over-actuation • Test Setup and Analysis • Improvements on the Current Setup • Conclusions Over-actuation of a wafer chuck Titel van de presentatie 2 Problem description Typically wafer chucks are actuated as rigid bodies. Larger wafers leads to heavier wafer stages: Z X 200 mm Wafer Width: 1.5 300 mm Wafer Thickn: 1.5 450 mm Wafer Y Depth 1.5 Depth 1.5 m kg Width: 1.5 > 3 x m kg Thickn: 1.5 > 11 x m kg Modal analysis Over-actuation of Modal a wafer analysis chuck Titel van de presentatie 3 Problem description Desire to have a LARGE chuck with LOW Mass and HIGH internal modes Z X Drawbacks of large wafers and chucks: • Larger actuation forces and deformation • Larger power dissipation and thermal load • Internal modes still critical to performance Modal analysis Over-actuation of Modal a wafer analysis chuck Titel van de presentatie Y 4 Alternative: Over-Actuation z Fz ALTERNATIVE means of ACTUATOR placement Challenge deal with infinitely many modes, without adding as many actuators and control complexity Fz Fz Actuation in nodes Fz Fz Fz Symmetrical actuation Over-actuation of a wafer chuck Titel van de presentatie 5 Eigenmodes of a chuck Modal analysis Over-actuation of Modal a wafer analysis chuck Titel van de presentatie 6 First eigenmode - Example Over-actuation of a wafer chuck Titel van de presentatie 7 Eigenmodes of a chuck Modal analysis Over-actuation of Modal a wafer analysis chuck Titel van de presentatie 8 Eigenmodes of a chuck • Actuators on nodeline? • Change nodelines? Modal analysis Over-actuation of Modal a wafer analysis chuck Titel van de presentatie 9 Topology optimization1 of chuck y x 1Langelaar Over-actuation of a wafer chuck Titel van de presentatie 10 TU Delft Optimization Strategy Modal Coordinates B T 1 ms 2 0 0 0 1 ms k 0 2 0 0 C Mechanics Physical Coordinates Minimize the contribution by varying actuator position a and cavity diameter d : 2 2 2 5 5 5 T T T min f 1 f Bz f 1 f BRx f 1 f BRy Z Rx Ry Over-actuation of a wafer chuck Titel van de presentatie 11 Optimization result I Modal analysis Over-actuation of Modal a wafer chuck Titel van de presentatie analysis 12 Eigenmodes of a chuck 184 Hz 270 Hz 270 Hz Actuator location Green zero displacement 349 Hz 521 Hz Over-actuation of a wafer chuck Titel van de presentatie 13 Optimization result II Modal analysis Over-actuation of Modal a wafer analysis chuck Titel van de presentatie 14 Optimization result II Modal analysis Over-actuation of Modal a wafer analysis chuck Titel van de presentatie 15 Realized Test Setup Three linear encoders Frame Z X Y Folded Flexures (3x), Actuator assembly (5x) Fixing Rz, X and Y Wafer chuck demonstrator motions in Z, Rx, and Ry Modal analysis Over-actuation of Modal a wafer analysis chuck Titel van de presentatie 16 Realized Test Setup Conventional actuation around COG Over-actuation around COG Over-actuation of a wafer chuck Titel van de presentatie 17 Measured Result I Modal analysis Over-actuation of Modal a wafer analysis chuck Titel van de presentatie 18 Measured Result II Modal analysis Over-actuation of Modal a wafer analysis chuck Titel van de presentatie 19 Control of the chuck 3 Sensors Chuck Dynamics Z RX 3 PID controllers Actuation matrix Loc ->CoG RY Control with standard industrial controller Bosch-RexRoth NYCe 4000 Over-actuation of a wafer chuck Titel van de presentatie 20 Performance of the setup Conventional Bandwidths: Z RX RY Standstill Performance RMS Z RX RY 50 Hz 60 Hz 50 Hz Over-Actuated Factor 2 in bandwidth, 4 in stiffness 102 Hz 100 Hz 100 Hz Factor 5 improvement 30 nm 150 nrad 135 nrad 7 nm 35 nrad 30 nrad Over-Actuation shows clear benefits compared to conventional actuation! Over-actuation of a wafer chuck Titel van de presentatie 21 Why still excitation of the modes?? Modal analysis Over-actuation of Modal a wafer analysis chuck Titel van de presentatie 22 Mode excitation analysis • Improved model • No Symmetry – Possible causes • • • • Actuator 5 Gravity Compensators Plate springs Chuck The analysis only partially explains the mode excitations Over-actuation of a wafer chuck Titel van de presentatie 23 Improvements of the current setup • Sensor-placement / Over-Sensing Over-actuation of a wafer chuck Titel van de presentatie 24 Control of the chuck 3 Sensors Chuck Dynamics Z RX 3 PID controllers Actuation matrix Loc ->CoG RY Control with: Matlab/Simulink, using xPc Target software Over-actuation of a wafer chuck Titel van de presentatie 25 Over-Sensing Adjust Sensorposition such, that the excitation of the modes is not converted to CoG movement • Place sensor in a node • Symmetric sensor placement Over-actuation of a wafer chuck Titel van de presentatie 26 Over-Sensing Over-actuation of a wafer chuck Titel van de presentatie 27 Over-Sensing • This sensor placement can distinguish the first and second eigenmode from the rigid body movement • Active damping of first eigenmode! Over-actuation of a wafer chuck Titel van de presentatie 28 Over-Sensing - Performance Conventional Over-Actuated + first mode active damping Bandwidths: Z RX RY 100 Hz 100 Hz 100 Hz 200 Hz 150 Hz 150 Hz Standstill Performance RMS Sensor 1 Sensor 2 Sensor 3 Sensor 4 4.0 nm 5.8 nm 4.6 nm 4.6 nm 1.8 nm 1.9 nm 1.9 nm 1.9 nm Over-actuation of a wafer chuck Titel van de presentatie 29 Conclusion • Over-actuation is succesfully implemented on a wafer chuck with an increased performance as result. • Symmetry is critical for the positions of the nodelines on the diagonals • Include sensor position optimization in the design phase • Use four sensors to be able to actively damp the first eigenmode Over-actuation of a wafer chuck Titel van de presentatie 30 Analysis and Performance of a lightweight over-actuated 450mm wafer chuck R. Boshuisen, PME 09-06-2010 Rein Boshuisen, PME Titel van de presentatie 31 Over-actuation of a wafer chuck Titel van de presentatie 32 Dynamic Analysis – effect of rotated chuck Over-actuation of a wafer chuck Titel van de presentatie 33 Dynamic Analysis – effect of Gravity Compensator Over-actuation of a wafer chuck Titel van de presentatie 34 Damping • Chuck is very lightly damped, increasing damping, reduces maximum peak-hight, leading to less sensitivity of the actuator placement Over-actuation of a wafer chuck Titel van de presentatie 35
