The US Naval Research Laboratory (NRL) has developed an innovative technique to release and transfer III-N material and devices. By using a thin sacrificial film of hexagonal Nb2N or Ta2N, which have lattice constants matched to SiC, III-N heterostructure material can be grown, processed into devices, and then released with a selective XeF2 dry etch. Transfer of III-N devices to alternative substrates can lead to substantial cost and performance improvements.

Advantages and Opportunities

  • Device quality III-N epitaxial material can be grown as latticed-matched Nb2N surface mimics SiC. (See below.)
  • Atomically-smooth surfaces (< 1 nm rms roughness) after release:
    • No chemical-mechanical polishing required prior to bonding.
    • Direct bonding of released layer to alternative substrate possible.
    • No SiC or free-standing III-N substrate consumed during process – enables substrate reuse.
  • Nb2N template is scalable to large wafer sizes. Good uniformity demonstrated on 3” SiC.
  • Can perform device, chip, or wafer-level transfer after full front-side processing is complete. (Nb2N is thermodynamically stable with III-N and SiC materials and tolerates high temperature processing.)
  • Dry release using XeF2 can be performed at low temperature (< 100 °C) - no annealing required during release.

Cross-sectional TEM image and electrical data illustrating device quality of N-polar GaN HEMT on Nb2N/SiC.

Licensing and Collaborative Opportunities

  • U.S. Patent Publication No. 2015-0021624 is available for license to companies with commercial interest.
  • Potential for collaboration with NRL researchers.

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