| 摘要 |
PURPOSE:To detect the position rapidly and automatically by utilizing either AC component, signal strength thereof is larger, of the phase sum signal output strength and phase difference signal output strength of a charged particle detector. CONSTITUTION:Mark signals obtained by a positioning mark signal detector 5 are supplied to an addition circuit 7 or a subtraction circuit 8 through a switching circuit 6. The signals passing through the circuit 8 are given to a pulse-height detecting circuit 13, and signals passing through the circuit 7 are differentiated by a differentiation circuit 9, a DC section is removed and the value is given to the circuit 13. The circuit 13 detects the crest value of both signals, and a comparison circuit 14 selects the crest value, the AC component thereof is larger, of the signals passing through the circuit 7 and the signals passing through the circuit 8, and transmits the signals to a CPU 15. The CPU 15 fixes the circuit 6 to processing, in which pulse height is larger, according to the signals. A signal wave-form phase-sum signal-processed or phase-difference signal-processed passes through an inversion circuit 10, and a signal wave- form having peaks symmetrical in the scanning direction of electron beams in response to the structure of the positioning mark is acquired. |
