Dual Aperture Diffractive Beam Combiner Consisting of Four Holographic Lenses: Application to Visible Light Lithography

Abstract

Diffractive beam combiners are preferred over reflective beam combiners in interference lithography so far as tolerance to spectral bandwidth of the laser source is concerned. Dual aperture interferometer consisting of four holographic lenses has been used advantageously by several researchers in speckle metrology and laser Doppler anemometry. In Present work, an innovative application of the dual aperture interferometer consisting of four holographic lenses has been proposed and investigated for its use as a diffractive beam combiner for visible light lithography to obtain periodic patterns of high spatial frequency in a very small area equal to focal spot of the lens system. Such cost-effective patterning of semiconductor wafer with periodic arrays over very small area may find its potential application in the production of high density integrated circuited and data stores media. Spatial frequency of periodic pattern can be varied by considering proper recording and playback geometry of holographic lenses.Lightweight and low-cost holographic diffractive beam combiner using visible light may be used advantageously to reduce the present high cost of extreme ultraviolet lithography.