A selective electron cyclotron resonance etch process was developed that etched GaAs over a 100 A In0.20Ga0.80As quantum well. The etch produced sharp anisotropic profiles with zero detectable resist erosion and a smooth etched surface. The etch was specifically tailored for transferring quantum box patterns with lateral dimensions ranging from 700 to 120 nm into the quantum well structure. Migration enhanced molecular beam epitaxy was used to regrow a GaAs cladding on the box sidewalls. Room temperature photoluminescence measurements of the quantum boxes showed a relative shift of 15.5 meV to higher emission energy and a reduction in intensity by a factor of 100 as the box lateral dimension was decreased. The roles of strain and misfit dislocations in these structures are discussed.