Ultra Precise Positioning of a Stage Driven by Pneumatic Bellows

Ultra precise positioning techniques that support nanotechnologies led by the semiconductor industry mainly require precision of nanometer order. Currently, it is piezoelectric elements that are most often used for positioning control of this order. Piezoelectric elements, however, are deficient in strokes and durability. In this research, we propose to use for ultra precise positioning control pneumatic bellows instead of piezoelectric elements, because the durability of pneumatic bellows is well proven. Specifically, we manufacture an elastic-hinge-guided, fine-motion stage which is driven by pneumatic bellows. In addition, we have developed a mathematical model for this fine-motion stage as well as its dynamic characteristics. We review feedback control to achieve ultra precise positioning, using the developed stage and mathematical model. As a result, we have succeeded in developing a fine-motion stage with longer strokes than ones driven by piezoelectric elements, though it is inferior in response. Positioning accuracy of the pneumatic-bellowdriven stage is ±5 [nm], which is tantamount to that achieved by piezoelectric elements.