PureB diode fabrication using physical or chemical vapor deposition methods for increased back-end-of-line accessibility

Shivakumar D. Thammaiah, Xingyu Liu, Tihomir Knežević, Kevin M. Batenburg, A.A.I. Aarnink, Lis K. Nanver*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Several methods of depositing pure boron (PureB) layers on silicon are examined with respect to their potential for fabricating advanced PureB (photo)diodes with back-end-of-line (BEOL) CMOS compatibility. PureB devices were fabricated in two different batch furnace chemical-vapor deposition (CVD) systems or by electron-beam-assisted physical-vapor deposition (EBPVD), and their electrical characteristics were found to be comparable to those of devices previously fabricated using single-wafer CVD and molecular beam epitaxy (MBE) systems. For all methods, the material properties of the B-layers and the I-V characteristics of the PureB diodes follow the same temperature dependence over the range 50 °C–400 °C. This was also the case for the EBPVD layers which were deposited at 50 °C and then annealed at higher temperatures, instead of being deposited at these temperatures as for the other methods. At 400 °C, the ability to achieve an optimal suppression of the electron injection into the PureB anode regions, corresponding to an electron current density of ∼20 pA/cm2, was verified for all methods. The advantages and disadvantages of each deposition method is evaluated with respect to equipment availability, B-layer selectivity, conformality, and thickness control. The batch furnace systems could be attractive for high-volume production, but hardware improvements as discussed here would be needed to reduce the effects of gas depletion. On all points except conformality, EBPVD appears to be a very good option for fabricating nm-thin B-layers suitable for fabricating high-performance 400 °C PureB diodes.

Original languageEnglish
Article number107938
JournalSolid-state electronics
Early online date3 Dec 2020
Publication statusPublished - Mar 2021


  • UT-Hybrid-D
  • Chemical-vapor deposition (CVD)
  • Electron-beam-assisted physical-vapor
  • Pure boron (PureB)
  • Ultra-shallow junctions
  • Batch furnace

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