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The semiconductor inspection apparatus using an electron beam in the vacuum environment requires high resolution and measuring accuracy because the semiconductor devices which are smaller and thinner are required by growing market of the smartphone and the tablet PC. Herewith, high positioning accuracy of XY stage working in vacuum environment is also required. However, it is hard to introduce the aerostatic bearing like semiconductor photolithography apparatus into vacuum environment due to technical difficulties and cost. Therefore, friction drive type XY stage was adopted. Nevertheless, it is difficult to precisely control and adjust characteristics and behavior as for friction drive XY stage which is working in vacuum environment. The characteristic of XY stage fluctuates in vacuum environment even though it has been precisely adjusted in the atmosphere. Moreover, nobody can re-adjust mechanical characteristics unless they open a vacuum chamber. It means an electron beam is halted, and the long time is necessary to restart emitting an electron beam. Therefore, this paper proposes a design approach which is useful for high precision positioning of XY stage in vacuum environment by the feedback of estimated disturbance which includes position dependent parameter. Position dependent parameter is determined by measuring evaluation function value at each position. Furthermore, proposed design method is also useful to maintain performance for aged deterioration. In this paper, issue of XY stage is mentioned at first. Then, a design approach which comprises a disturbance observer including position dependent parameter and state feedback is described. At last, experiment results are shown.

A Design Method of Precise Positioning Stage in Vacuum Environment by Disturbance Observer with Position Dependent Parameter