Patent ID: 7113360

Claim:
An electron beam recording system for forming concentric circular servo patterns on a substrate disk, comprising: an electron beam column for generating a modulated electron beam responsive to a format modulation signal, the electron beam column including deflection plates for controlling deflection of the modulated electron beam in response to a deflection signal; a turntable, for rotating the substrate disk and simultaneously translating the substrate disk, to move the substrate disk relative to the electron beam, while applying the electron beam to a surface of the substrate during a plurality of successive rotations of the substrate disk; and a signal generator for supplying the deflection signal to the deflection plates of the electron beam column, wherein: the deflection signal from the signal generator comprises a cyclical increasing ramp signal for producing a cyclical deflection of the modulated electron beam, cycles of the ramp signal substantially correspond to rotations of the substrate disk by the turntable, the format modulation signal comprises a set of pulses during each rotation of the substrate disk by the turntable, during each respective rotation of the substrate disk, the signal generator starts increasing of the ramp signal from a first level in response to the first one of the pulses of the set during the respective rotation and returns the ramp signal from a second level to the first level at a time prior to completion of the respective rotation, and the increase from the first level to the second level provides an increase in deflection of the electron beam substantially equal to one track pitch during each cycle of the ramp signal, so as to cause the system to form patterns of servo features in concentric circles on the substrate disk during successive rotations of the substrate disk on the turntable.