193Nanosensor Laboratory
control over etching prole vis-à-vis equipment cost, installation, mainte-
nance, and infrastructural expenses are prime considerations. Anisotropic
wet etching of <100> silicon is an established technique that has been widely
used for realization of microstructures. The use of dry etching is restricted
by prohibitively high cost to specialized applications where other methods
are inadequate. Dry etching is a high-precision and controlled process but
also high-cost-enabling technology.
Under what circumstances, is dry etching essential? If feature resolution in thin
lm structures is of primary concern, or vertical sidewalls are needed for
deep etchings in the substrate, dry etching must be irresistibly done. Under ...