Electron beam type pattern transfer apparatus

Claim 1

An electron beam type pattern transfer apparatus comprising: a light source; a vacuum container made of non-magnetic material and having a window through which an ultraviolet ray passes; a photoelectric mask supported in the vacuum container and adapted to receive the ultraviolet ray from said light source and emit photoelectrons corresponding to a predetermined transfer pattern; a power source connected between said photoelectric mask and a sample disposed parallel to said photoelectric mask such that it faces the photoelectric mask with a predetermined distance left therebetween, and adapted to apply an acceleration voltage for accelerating said photoelectrons; a pair of focusing magnets arranged around the axis of the vacuum container such that they are located one at one outer side and one at the opposite outer side of said vacuum container and comprised of superconductive coils, respectively, for creating simultaneously a uniform and stabilized vertical magnetic field between the photoelectric mask and the sample; and a magnet drive source connected to the focusing magnets for excitation, in which the sample is illuminated with the photoelectrons emitted from the photoelectric mask so that a resist image corresponding to the transfer pattern is formed on the sample; and a persistent current switch connected in parallel between the superconductive coil of the focusing magnet and the magnet drive source to switch the superconductive coil to a persistent current mode for minimizing the ripple of the magnetic field.