Inductively coupled plasma (ICP) dry etching of type II InAs/GaSb superlattice for focal plane arrays

Infrared(IR)photo detectors based on InAs/GaSb type II superlattice have developed quickly in recent years. Many groups show great interest in InAs/GaSb superlattice detector for its superiors as high quantum efficient, high working temperature, high uniformity and low dark current densities. Inductively coupled plasma(ICP) etching of GaSb and InAs/ GaSb superlattices were performed using Cl₂/Ar/CH₄/H₂. This paper introduceste inductively coupled plasma( ICP) etching of Inas/GaSb with SiO₂ mask by the Cl₂/Ar/CH₄/H₂ mixed-gas process. The effects of process parameters such as gas combination, ICP and RF power on the etch rate and quality of InAs/GaSb It is found that the ratio of Cl₂ flow rate significantly affects the etch rate, due to the trade-off between physical and chemical component of etching. The etch rate of InAs/GaSb increases with the increase of percent of Cl₂, there will InClx remains in the etching channel when the etching depth exceeded 2μm, which can stop the etching going on. This phenomenon can be eliminated by decrease the Cl₂ ratio,to make sure the etching depth reach 6μm under a certain low etching rate. The surface morphology and SEM of the superlattice material after etching shows that dry etching morphology is better than wet etching.After the electrode is grown, the superlattice chip have a good diode characteristic curve.