Investigation of ICP dry etching of InAs/GaSb type-II superlattice LWIR photodetector

Design and performance of dual-band MWIR/LWIR focal plane arrays based on a type-II superlattice nBn structure

“…Then, MWIR and LWIR bands are individually detected by a bias direction applied to the pixel electrode: negative (−) bias for MWIR and positive (+) bias for LWIR. The one-band nBn devices were fabricated through the steps of pixel isolation, posttreatment, passivation, and metallization processes [12][13][14][15][16]. However, the dual-band nBn device should be dry-etched more deeply than the one-band nBn device for pixel isolation because of the thicker absorber layer.…”

“…3. First, LWIR absorber of each pixel was isolated by fully etching from the top contact layer to the barrier layer using inductively coupled plasma reactive ion etch (ICPRIE) under following conditions [15]: process temperature 200 °C, working pressure 6.66  10 −4 kPa, BCl3 flow 5 sccm, RF power 270 W, and ICP power 300 W. And then, to alleviate a potential surface damage of the etched LWIR absorber caused by plasma radicals, hydrogen (H2) plasma treatment was in situ performed using ICPRIE under following conditions [16,17]: process temperature 200°C, working pressure 6.66  10 −4 kPa, H2 flow 5 sccm, RF power 30 W, and ICP power 500 W. After SiO2 passivation film was deposited using an inductively coupled plasma chemical vapour deposition (ICPCVD) equipment to protect the surface of the LWIR absorber, the first MESA process for isolating the LWIR pixels was finished. Second, MWIR absorber of each pixel was isolated by fully etching from the barrier layer to the bottom contact layer under the same conditions as the pixel isolation process of the LWIR absorber.…”

640 x 512 dual-band midwave and longwave infrared focal plane array at i3system

“…The MWIR absorber layer was grown earlier and thicker than LWIR absorber to minimize a spectral crossover when infrared is incident on the backside of the dual-band FPA [13]. The dual-band MWIR/LWIR FPA was fabricated following the process sequence of the InAs/GaSb LWIR nBn devices reported in previous studies [13,14,15,16,17]: dry-etch for pixel isolation, post-treament, passivation film deposition, electrode area etching, and metallization. However, the dual-band nBn device should be dry-etched more deeply than the single-band nBn device for pixel isolation because of the thicker absorber layer including MWIR and LWIR absorbers.…”

The use of one-component plasma in the icp-rie etching process of periodic structures for applications in photodetector arrays

“…In dealing with plasma etching, various parameters can be controlled, such as generator power, substrate temperature, chamber pressure, and the plasma ratio and composition. In [12] using a one-component plasma of BCl 3 is reported. However, achieving a uniform etch rate for heterostructures containing two different materials is difficult as the chlorine-based plasma technology suffers from both the presence of indium chlorides on the etched surfaces and the different etching rates of the InAs and GaSb materials [13][14][15].…”

“…This article focuses on examining the possibility of using BCl 3 single-component plasma in the dry etching process in order to obtain smooth and vertical sidewalls of SL mesa structures in a repeatable way. The BCl 3 flow rate used for etching should be relatively low to prevent excessive etching of the sample and relatively high to avoid excessive elongation of the etching process [12]. The measurable goal was to obtain a periodic mesa-shaped pixel structure with perpendicular, smooth sidewalls and rectangular corners.…”