An X-Ray Stepper

With design rules for highly integrated circuits approaching or even attaining the sub-micron range, a mask aligner which is not working near its resolution limit is needed in order to provide enough process latitude. A candidate for this kind of machine is an x-ray stepper operating at a safe gap between mask and wafer and using a synchrotron radiation source. A mechanical stepping system, a gap setting mecnanism and an autoalignment scheme, in addition to the adaptation to synchrotron sources are described. An outlook on the economical advantages of this kind of lithography versus optical steppers is given.