Characterization of damage in electron cyclotron resonance plasma etched compound semiconductors

Plasma-induced changes to the near-surface of compound semiconductors can be categorized as follows: (i) introduction of deep-level, non-radiative centers due to energetic ion bombardment, (ii) passivation of dopant impurities by atomic hydrogen, even when hydrogen is not an explicit part of the plasma chemistry, (iii) alteration of the near-surface stoichiometry through preferential loss of the more volatile element, (iv) deposition or creation of contaminating films, especially polymers. The use of high density plasma sources such as electron cyclotron resonance or inductively coupled plasma reduces ion bombardment damage except at very high ion fluxes, and allows use of hydrogen and polymer free plasma chemistries such as Cl-2/Ar to etch all III-V compounds. Control of the near-surface stoichiometry is possible by balancing the removal rates of group V and group III etch products.