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.
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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