Concept, construction and commissioning of an alignment system for deep X-ray lithography

An in-house-made alignment system for deep X-ray lithography is presented that features low costs, low weight and little demand in space. Synchrotron radiation illuminates alignment marks on mask and substrate. The radiation transmitted through these alignment marks is detected by X-ray-sensitive diodes. The mask is fixed to the vacuum chamber, whereas the substrate is mounted on a six-axis kinematic stage. The information about the degree of alignment is the obtained photocurrent, which reaches its maximum at the best alignment position. Variation of the photocurrent is an error signal in a feedback loop. A slit screen protects the resist in the pattern area from irradiation during the alignment procedure. The features of the alignment system offer guidelines for research groups interested in upgrading their system as well.