A magnetically levitated, automated, contact analytical probe tool

With the challenge of the shrinking dimensions in the fabrication process, demands are growing for higher precision and more powerful analytical probing stations to be used for characterization and failure analysis of integrated circuits. A magnetic levitation-based approach to analytical probing stations is proposed and investigated in this paper. This approach permits the process to be automated while maintaining better resolution and easier operation than is currently available. Further, force control can be implemented to ensure that the probe contact does not scratch the device under testing. Feedback controllers are designed and used in both the suspension and the XY positioning. The suspension motion controller is implemented in analog circuitry while the XY motion controller is implemented in a digital controller. An air gap sensor and optical position sensors are used for the position feedback. A simple open loop control method is derived for the force control. A positioning repeatability of 0.2 μm and a force repeatability of 80 mgf are observed from the experimental results