Contacting of buried InP-based layers by epitaxial overgrowth over patterned tungsten features

Abstract

Features of tungsten have been embedded in InP, with the aim of forming contacts to buried InP-based layers. The conditions for overgrowing W are investigated for various orientations using a ring-structure. The highest lateral growth rate is observed for angles of 30/spl deg/ and 60/spl deg/ from the [110]-direction and wires oriented in these directions may be completely overgrown without the formation of voids above the metal. A specific contact resistance of 4 10/sup -5/ 1/2 cm/sup 2/ has been measured between buried contacts and the n-type InP. Finally, we have studied the dependence of the intrinsic metal resistance on the overgrowth process. The data show that the metal resistance is reduced and values of about 30 1/2 /Sq for 30-nm-thick features are obtained.