Method of fabricating three dimensional gallium arsenide microelectronic

Abstract

Optoelectronic devices (16) are formed on a first surface (12) of a gallium arsenide substrate (10) using selective ion implantation. Signal processing devices may be formed on a second, opposite surface (14) of the substrate (10) using selective ion implantation (38) and/or selective epitaxy (22,24),(40). Vertical interconnects (34,46) are formed between the first and second surfaces (12,14). Alternatively, a gallium arsenide buffer layer (54) may be grown on the first surface (12) of the substrate (10), and the signal processing devices formed on the buffer layer (54) using selective ion implantation (58,60,62) and/or selective epitaxy (76,78,80,82). Dielectric (50) and/or conductive metal (52) layers may be formed on selected areas of the first surface (12), and the buffer layer (54) grown from exposed areas (56) of the first surface (12) over the dielectric (50) and/or metal (52) layers using lateral epitaxial overgrowth organometallic chemical vapor deposition. The signal processing devices may be formed in areas of the buffer layer (54) which overlie the exposed areas (56) of the substrate (12), and/or over the dielectric (50) and/or metal (52) layers. The present method enables metal-semiconductor field effect transistors (MESFET), high electron mobility transistors (HEMT) and heterojunction bipolar transistors (HBT) to be monolithically integrated in a vertical fashion for close packing density.