Intra-/Inter-Chip Optical Communications 279
cently, N. Sherwood-Droz and coworkers have developed a new method based
on usual CMOS techniques for waveguide formation and integration [100].
SOI waveguides usually have a rectangular geometry and are built through
micro-lithography, or a negative-photo method, and then etching. The au-
thors of reference [100] proposed the use of thermal oxidation to generate the
necessary silica layer beneath the waveguide but protecting the original crys-
talline silicon with a three-sided cap of a very high oxidation temperature and
compatible material, Si
3
N
4
. This technique is similar to other known CMOS
techniques as LOCOS or SWAMI. The complete fabrication process, described
in Figure 7.25, starts with a crysta ...