LASER DEPOSITION OF DOPED SILICON.

The pyrolytic deposition of silicon from silane by a focussed argon ion laser makes possible the precision 'writing' of conducting tracks of doped silicon without the need for photolithography or chemical etching. Possible applications are for integrated circuit, hybrid circuit or thin-film circuit interconnections. This paper is only concerned with doped silicon patterns deposited on p-type (100) crystalline silicon wafers having a uniform layer of 100 nm of thermal silicon dioxide for electrical isolation from the substrate. The process uses a computer to control the laser beam and translation stage, with menu-driven software to select laser power, exposure period, substrate position and movement. The 514 nm emission from a 8 W argon ion laser is beam-expanded and focussed through a Spectrosil B window to a 6 mu m spot on to the substrate held inside a stainless steel reaction chamber.