Micro object handling under SEM by vision-based automatic control

There is a great demand for arrangement of micro objects smaller than 100 mu m with high accuracy and reliability in order to construct micro devices. Since micro objects tend to adhere to other objects by electrostatic force, we can pick them up easily by contacting with a needle tip instead of grasping by tweezers. On the contrary, it is difficult to place them on a substrate. To solve this problem, we have proposed a handling method by controlling the facing area, i.e. picking up the object by contacting with the center of the tooltip plane, and placing it by contacting with the edge and also inclining the tool. However it is difficult to execute this operation by manual control, because it requires delicate control of the manipulator, not to break or flip away the object. 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 demonstrate a completely automatic arrangement of several micro objects of 30 mu m in diameter under SEM monitoring.