Forming micro- and nanoscale structures on various substrates is a corner-stone process requirement in semiconductor, photonics and Micro Electro Mechanical Systems (MEMS) manufacturing. While traditional lithography methods continue to be widely used, in recent years a more nonconventional lithographic technique has been established for specific applications. Imprint lithography, often also referred to as Nano Imprint Lithography (NIL), is a mechanical way of patterning polymer materials. The technique enables small feature sizes beyond the limitations of optical photo-mask based approaches.
This work provides on overview of basic imprint principles on individual substrates and specifically discusses high volume manufacturing applications which have now become commonplace. The requirements on masters, imprint molds, materials and process equipment are highlighted and the suitability of various imprint technologies is being assessed. Roll-to-roll imprint methods are not covered in this review.
One key driver for high volume manufacturing via Imprint Lithography has been the growing demand for Photonics components in Consumer Electronics, Automotive and Vision Systems. Standard manufacturing methods like grinding and polishing are usually too expensive. Wafer Level Optics (WLO) Imprint lithography allows to manufacture thousands of refractive microlens arrays, diffractive optical elements (DOE), fiber couplers, gratings, beam-splitters, phase plates (free-form) and other planar structured components at high throughput and relatively low cost.
In addition to the overview of the current status of wafer level imprint technology, an outlook of future technology developments in the field of imprint lithography for wafer level optics (WLO) applications and processes is given. The presentation also offers a perspective of the critical importance of optical system design, mastering, stamp manufacturing, stamp lifetime, process industrialization, wafer stacking, wafer-level packaging (WLP), metrology and inspection when manufacturing Photonics components.