711Microwave Integrated Circuits
suitable to grow thin epitaxial layers of sub-micron order. It is also suitable
to grow multi-layered structures in which precise doping, composition con-
trols are required.
16.6.4 Lithography
In this process, patterns of geometric shapes on the mask are transferred to
a thin layer of radiation-sensitive material known as resist, for covering the
surface of the SC wafer. The resist patterns are not permanent elements of
the nal device but only replicas of circuit features. Its various types include
(i) electron beam lithography, (ii) ion beam lithography, (iii) optical lithogra-
phy and (iv) x-ray lithography.
16.6.5 Etching and Photo-Resist
It provides selective removal of SiO
2
to form openings through which ...