Reactive ion etching of indium compounds using iodine containing plasmas

Abstract

A reactive ion etching process and system using iodine containing plasmas for etching InP, InGaAs, and InGaAsP is described. A special system was constructed to deliver iodine to an etching chamber and trap the iodine to prevent damage to the pumping system. Etch rates and profiles were determined using both large area and grating test patterns with linewidths as small as 20 nm. Using mixtures of Ar:I2 and H2 :HI:CH4 at a substrate temperature of 100 °C, lines 20 nm wide and 1 μm deep with vertical sidewalls were etched in InP at a rate of 200 nm/min using a Ni mask. The use of this etching technique in the fabrication of highly reliable InGaAsP distributed feedback lasers with a unique structure is also described.