Highly Dynamic 4DOF Piezo Wafer Stage for Inspection and Metrology Introduced
Efficient wafer inspection and metrology are key success factors in semiconductor manufacturing. In addition, they are becoming more demanding, challenging, and costly as feature sizes shrink and design complexity increases. Metrology processes are therefore highly dependent on precise wafer positioning to enable the fast and reliable analysis of defects or particles at each step of the manufacturing process to prevent yield loss. PI offers proven wafer scanning subsystems that take advantage of piezo technology to meet demanding process requirements where conventional electromagnetic solutions reach their limits.
Leveraging decades of piezo nanopositioning technology experience PI’s newest wafer inspection solution is based on a hybrid kinematics design, combining Piezo-Walk motors and piezo stacks to achieve both long travel and highly dynamic, ultra-precise motion. This integrated 4-DOF solution reduces equipment complexity, integration efforts, costs, and risks.
With the development of an innovative hybrid kinematics configuration, PI expands the system options for wafer platforms with four independent degrees of freedom: Tip, Tilt, Z and rotation around Z. Loading and unloading is performed by an integrated wafer lift. The hybrid kinematics configuration features unique piezo actuators for high-precision Z-axis motion. These provide fast step-and-settle over long travel ranges as well as real-time dynamic motion over small areas. Adopters of the new technology are streamlining their design processes and achieving greater precision and reliability. At the same time, they are able to minimize equipment complexity and integration efforts, thereby reducing costs and risks.
Piezo-Walk motors are self-locking at rest, adding no servo dither and heat, unlike other motion techniques. The high bandwidth of the short-travel piezo stack actuators allows for dynamic tracking and error compensation of external disturbances from long travel XY wafer stages.
The 4DOF module can also correct for rotational wafer misalignment and takes wafer thickness and machine static characteristics into account. The high-stiffness design of the Tip-Tilt drive module provides extremely fast step and settle (better than 10msec) and position stability (better than 0.05µrad).
For more information: www.pi-usa.us
