Micro object handling under SEM by vision-based automatic control

There is a great demand for the highly accurate and reliable arrangement of micro objects smaller than 100 mu m in order to construct micro devices. Since micro objects tend to adhere to other objects by electrostatic force, it is possible to pick them up easily by contact with a needle tip instead of grasping by tweezers. On the other hand, it is difficult to place them on a substrate. To solve this problem, we have proposed a handling method by controlling the contact face area, i.e. picking up the object by contact with the center of the tool-tip plane, and placing it by contact with the edge and also inclining the tool. However, it is difficult to execute this operation by manual control, because it requires delicate movement by the manipulator, in order not to break the object or flip it away. In this study, we automate this pick-and-place operation by visual and force control. Moreover, to arrange micro objects with high accuracy and reliability, all necessary functions such as calibration, object search, and positioning are integrated, and an automatic handling system is constructed. We successfully demonstrated a completely automatic arrangement of several micro objects of 30 mu m in diameter under SEM monitoring.