A new type pattern generator applied to the electron-beam exposure system

Abstract

This paper describes a new type pattern generator, used in the scanning e-beam system suitable to generate smooth skewed vector with given slope. The initial coordinate of the vector is defined by two 16 BIT DACs, each equipped with a fixed reference source, and the components of the vector are given by other two 12 BIT DACs, each equipped with a variable reference source digitally controlled by a common triangular wave generator. Digital controlled period of the triangular wave ranges from 1 μs to 10 s. A high speed dynamic zero-correction deflection amplifier is applied to the pattern generator. The deflection amplifier and coil system are optimized to give a flat frequency response to 5 or 10 Mc, and the output current ±0.5 to ±5 A. Experimental exposure has been practiced in the 20×20 mm2 scanning field with smooth skewed vectors, location accuracy 0.03%. Scanning speed is equivalent to 100 kc to 10 Mc of the digital point–to–point scanning e-beam system.