Native Oxide Mask for Zinc Diffusion in Gallium Arsenide

Abstract

This paper reports the first use of an amorphous native oxide on gallium arsenide to mask against zinc diffusion. Anodic oxides were grown at low temperature (≤100°C), and stripes were defined in this oxide using standard photolithographic processing. These samples were diffused, after an appropriate annealing cycle, in a closed system using a zinc source <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="ML1" overflow="scroll"> <mml:mo stretchy="false">(</mml:mo> <mml:msub> <mml:mi mathvariant="normal">Zn</mml:mi> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> </mml:msub> <mml:msub> <mml:mi mathvariant="normal">As</mml:mi> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> <mml:mo>+</mml:mo> <mml:mi mathvariant="normal">GaAs</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:math> at 612°C for times up to 2 hr. Diffusion depths were measured using a lap and stain procedure, and the results showed the oxide to be effective as a zinc barrier. Furthermore, no anomalous lateral underdiffusion was observed indicative of a high integrity interface between the oxide and semiconductor.