Image Number 12 for United States Patent #4980896.
An x-ray lithography system is disclosed in which x-rays are generated by directing a high energy laser beam against a metal target to form an x-ray emitting plasma. The x-rays from the plasma are then directed through a mask towards a resist covered wafer to cause a patterned exposure on the wafer resist coating. The mask, the portion of the target which the laser beam strikes and the portion of the wafer to be exposed are all within an evacuated chamber. The laser, prior to entering the chamber, is split into two separate beams, each of which are focused and directed through a window in the side of the chamber towards the same spot on the target. Apparatus, including an air bearing, seal and positioner, is provided to move the target at periodic intervals. Similar apparatus is provided to move the wafer from exposure section to exposure section. The laser beam system includes a face pumped laser beam amplifier and unidirectional beam expanders to allow the maximum energy to be transferred to the laser beam by the amplifier. A series of two or more laser pulses are provided in order to maximize the energy obtained from the laser amplifier. A magnet and a membrane shield are also provided to prevent high energy particles and dust contaminants from the plasma from effecting the lithography process. A materials handling device is provided for moving wafers, targets and masks and an alignment system operating within the evacuated chamber, positions of the wafer with respect to the mask prior to the exposure thereof.