THICKNESS MEASUREMENTS OF THIN ANODIC OXIDES ON GAAS USING ATOMIC-FORCE MICROSCOPY, PROFILOMETRY, AND SECONDARY-ION MASS-SPECTROMETRY

Techniques to determine the thickness of thin (30-200 Angstrom) anodic oxide films on p-GaAs (100) are reported. The layers were grown poten tiostatically in 0.3 M NH4H2PO4 (pH 4.4) solution. By lithographic tec hniques, several series of squares were etched into the oxide and the step height was measured using both atomic force microscopy (AFM) and a stylus surface profiler (Dektak). Secondary ion mass spectrometry (S IMS) profiles of samples prior to and after the photolithographic trea tment show that neither the thickness nor composition of the layers ar e affected by the treatment. The thickness values obtained in the inve stigated range show standard deviations better than +/-9 Angstrom (AFM ) and +/-22 Angstrom (Dektak) and correlate well in a linear relation to SIMS sputter times to the interface. (C) 1996 American Institute of Physics.