I'm sure that plane is very useful.
Check out the co-inventors on the Referenced Patents of Bozler et al.:
Bozler; Carl O.
Fan; John C. C.
McClelland; Robert W.
Bozler is still at Lincoln Lab, Solid State Division, as is Molnar. McClelland was one of the original people that Fan took with him to Kopin, but he is no longer there.
These guys certainly know a thing or two about lift-off techniques. <g>
It probably pops right off like so (from the Detailed Description):
Given that a difference in thermal expansion coefficient exists between the growth substrate and the epitaxial nitride layer, as is typically the case, strain between the nitride layer and the substrate generally is produced during cool down of the substrate assembly; during cool down, the substrate and epitaxial materials will contract, as they cool, to differing degrees, depending on the difference between their thermal expansion coefficients. The resulting strain between the GaN layer and the underlying substrate induces a mechanical fracture mechanism along the substrate's parallel plane of weakness, resulting in an automatic separation of the GaN layer from the growth substrate.
In Claim 14, "the layer of material characterized by a plane of mechanical weakness comprises a layer of BN."
It's interesting that Fan is keeping his finger in there; these patents were filed in the early to mid 90s, long after he left to start Kopin (1984). I wonder if M.I.T. has licensed these patents to anyone?
WT |
