Diamond photodetectors for next generation 157-nm deep-UV photolithography tools

Abstract Next generation photolithography stepper tools will operate at 157 nm and require 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 demanding requirements of this application. Diamond, which is intrinsically visible blind and radiation hard, is an obvious candidate for consideration. In this paper we report the results of the first study to assess the viability of thin film polycrystalline diamond photodetectors for use in 157 nm F 2 –He based laser lithography tools. Co-planar inter-digitated gold photoconductor structures were fabricated on free standing thin film diamond and exposed 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 been measured and are compared to the response of a standard vacuum photodiode. The suitability of the diamond devices for use at 157 nm is discussed.