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Microelectronics have evolved from mainframe computers to desktop PCs to tablets and mobile devices, and now to wearables. For many optics applications, there is also a trend to move from conventional optics to micro-optics and nanooptics. These two trends meet at optical see-through augmented reality, both from the user experience and the underlying technology. With our sights on eventual high-volume manufacturing of waveguide combiners, such as surface relief gratings, we take what we have learned from technology development and present challenges that must be overcome to achieve high yields in high volume production. In this report we discuss inline metrology and inspection challenges and opportunities starting with processes related to the transparent substrates: slicing, edge grinding lapping, polishing, marking and cleaning. Resulting challenges include roughness, scratches, particles, thickness variation, flatness, bow, warp, wedge and the like. Similarly for waveguide patterning on the substrate, whether it is with optical lithography or nano-imprint lithography, there are challenges that must be overcome. These include film thickness variations, maintaining critical dimensions such as feature width, height, pitch and profile, as well as defectivity resulting from particles, scratches, residue/stains, etc. Finally, diced eyepiece inspection challenges include scratches, particles, residue, color variation, chips and cracks. We describe both inline process control and impact on downstream optical properties such as modulation transfer function. While there are many similarities between augmented reality waveguide combiner manufacturing and silicon IC semiconductor manufacturing, there are many important unique challenges.
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