Pure boron-doped photodiodes: A solution for radiation detection in EUV lithography

A pure boron chemical vapor deposition (CVD) technology, which forms delta-doped boron surface layers during diborane B2H6 exposure at 700degC, has been successfully used to fabricate silicon-based p+n photodiodes for radiation detection in the extreme-ultra-violet (EUV) spectral range. Outstanding electrical and optical performance has been achieved in terms of extremely low dark current (< 50 pA at reverse bias of 10 V), near theoretical responsivity (0.266 A/W at 13.5 nm wavelength), and excellent stability to high radiation doses (< 1% responsivity degradation after 0.2 MJ/cm2 exposure). Therefore, the diodes are suitable candidates for photon detection functions in the next-generation EUV lithography systems.