Diamond photodetectors for next generation 157-nm deep-UV photolithographytools

Next generation photolithography stepper tools will operate at 157 nm and r equire robust solid state photodetectors to ensure efficient operation and facilitate direct beam monitoring for photoresist exposure dosimetry. There is currently no commercial detector system able to fully meet all the dema nding requirements of this application. Diamond, which is intrinsically vis ible blind and radiation hard, is an obvious candidate for consideration. I n this paper we report the results of the first study to assess the viabili ty of thin film polycrystalline diamond photodetectors for use in 157 nm F- 2-He based laser lithography tools. Go-planar inter-digitated gold photocon ductor structures were fabricated on free standing thin film diamond and ex posed to pulses from an industrial F-2-He laser in the fluence range 0-1.4 mJ cm(-2). The electrical and optical characteristics of the devices have b een measured and are compared to the response of a standard vacuum photodio de. The suitability of the diamond devices for use at 157 nm is discussed. (C) 2001 Elsevier Science B.V. Ah rights reserved.