General aspheric refractive micro-optics fabricated by optical lithography using a high energy beam sensitive glass gray-level mask

General aspheric refractive microlens arrays with an almost 100% fill factor are useful in a wide range of applications ranging from display, optoelectronic interconnections, or improving the efficiency of detector arrays to lithography techniques utilizing microlens arrays. In this article a technique will be discussed which allows the microlithographic fabrication of general aspheric non rotationally symmetric refractive lenses with a 100% fill factor. A gray-level mask based on high energy beam sensitive (HEBS) glass is used to pattern a thick (4-5 micron) photoresist layer. After development, the refractive structure is transferred into the substrate material using a chemically assisted ion beam etching (CAIBE) process. The HEBS-glass gray-level mask is generated by a electron-beam writer, allowing for complete freedom in terms of the shape and location of the lenses. (C) 1996 American Vacuum Society.