公开(公告)号：DE3367290D1

公开(公告)日：1986-12-04

申请号：DE3367290

申请日：1983-01-14

Applicant: IBM

Inventor： CANN GEORGE WINSTON ,  DAVIS DONALD EUGENE ,  TROTTER RALPH ROBERT

IPC: G05D3/12 ,  G05B19/23 ,  G05D3/20 ,  H01L21/027 ,  G05D3/14 ,  G05B13/02

Abstract: An X-Y positioning system for electron beam lithography employs an adaptive drive system for feedback control. A gradually increasing drive voltage, superimposed upon a step wave, is summed with the position error signal to achieve position within the system deadband zone. The drive voltage, while superimposed upon the error voltage, increases until mechanical friction and drift in the deadband zone are overcome. A function generator alters the error signal such that the combined error signal and drive voltage cause the system to approach the null point minimizing servo oscillations. A limit circuit determines when the system has reached a set of inner limits and generates an operative output signal to the signal controller which continues until the position exceeds a second, outer set of limits.