Abstract
Subtractive photonics is presented as a method
for implementing photonic waveguides into any bulk CMOS
or electronics process. Metal and glass are patterned in the
backend layers by the foundry to reveal suspended dielectric
waveguides when the metal is etched away. This method requires
a simple wet etch and provides waveguiding of light up to the
visible regime using the broad transparency windows of silicon
oxides. Mechanical, chemical, and photonic considerations are
discussed, and photonic d