INDUCTIVELY-COUPLED PLASMA-ETCHING OF INGAP, ALINP, AND ALGAP IN CL-2AND 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, wit h additives of Ar, N-2, or H-2), source power, radio frequency chuck p ower, and pressure. Smooth anisotropic pattern transfer at peak etch r ates 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 t o the surface to produce a strong chemical enhancement of the etch rat e, 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.