Inductively coupled plasma etching of InGaP, AlInP, and AlGaP in Cl2 and BCl3 chemistries

Dry etching of InGaP, AlInP, and AlGaP in inductively coupled plasmas (ICP) is reported as a function of plasma chemistry (BCl3 or Cl-2, with additives of Ar, N-2, or H-2), source power, radio frequency chuck power, and pressure. Smooth anisotropic pattern transfer at peak etch rates of 1000-2000 Angstrom.min(-1) is obtained at low DC self-biases (-100V dc) and pressures (2 mTorr). The etch mechanism is characterized by a trade-off between supplying sufficient active chloride species to the surface to produce a strong chemical enhancement of the etch rate, and the efficient removal of the chlorinated etch products before a thick selvedge layer is formed. Cl-2 produces smooth surfaces over a wider range of conditions than does BCl3.