{'fraction_non_alphanumeric': 0.017857142857142856, 'fraction_numerical': 0.0, 'mean_word_length': 5.404761904761905, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
A Direct-Reticle-Referenced Alignment System

A direct-reticle-referenced die-by-die alignment system operating at the actinic wavelength has certain unique advantages and some advantages in common with other systems. The unique advantages are the elimination of baseline and baseline associated problems and the minimization of optical aberrations of the alignment signal. The other advantages are the capability of video collection, digitization and manipulation of large data bases, the opportunity to chose and vary algorithms to accommodate processed wafers and the minimal demands imposed upon processing. The cost of using the actinic wavelength is the limitation in the number of photons available for alignment and the resultant reduction of the signal-to-noise ratio. There are certain problems generic to most other die-by-die alignment systems. Both optical and mechanical complexity is added to the lithographic system. Thin-film structures must be tailored to accommodate the demands of contrast, and photoresist modulation effects can introduce uncertainties in alignment. We shall briefly describe these effects in the context of the Field Alignment System, describe some of our measurements on this system, particularly those pertaining to the efficacy of the algorithm and comment upon the alignment capability of this system.