Deep dry etching of GaAs and GaSb using Cl2/Ar plasma discharges

Abstract

Deep dry etch processes for GaAs and GaSb are investigated. Reactive ion etching in Cl2/Ar plasma discharges is used to pattern GaAs and GaSb with a single-layer soft mask resist. Soft masks have many advantages over (metal) hard masks such as easy and inexpensive processing, low pinhole density, and high etching reproducibility. Using TI35ES, an image reversal resist developed by MicroChemicals, GaAs etch profiles of up to 25 μm depth and GaSb structures of more that 50 μm depth are obtained revealing considerable dimensional stability. Even for etch durations of more than 50 min the resist can be easily removed from the sample surface after the etch process. Roughnesses of etched surfaces of less than 1 nm (rms, measured by atomic force microscopy) are obtained after reactive ion etching for both materials. Photoluminescence measurements reveal that the surface stoichiometry is conserved during the etching step. Deep dry etching of GaAs and GaSb can be exploited for example to fabricate fiber or capillary connections to and between optoelectronic devices or to create substrate windows for backside-illuminated photodetectors in the infrared wavelength range.

Inductively coupled plasma etching of III–V antimonides in BCl3/SiCl4 etch chemistry

“…The etching conditions used for our experiments displayed very high selectivity of 1:10 between AZ-4903 etch mask and GaSb, eliminating the need for very thick layers of photoresist. The very high etch rate of 4 μm/min achieved in our experiments was implemented for the deep dry etching process [13]. This is particularly advantageous, since the high etch rate considerably reduces the etching time required, minimizing chamber contamination among other problems.…”

Dry etching and surface passivation techniques for type-II InAs/GaSb superlattice infrared detectors

“…The Cl 2 /Ar dry etch recipe used in this work is based on the optimised parameters for reactive ion etching of GaSb reported by Giehl et al 6 . Dry etching experiments were performed in a Oxford Instruments Plasmalab System 100 inductively coupled plasma (ICP) etcher.…”

“…To determine the etch rate, test pixels of GaSb and InAs/GaSb T2SL materials were initially patterned with a thick photoresist and dry etched using the parameters reported in Ref. [6]. The etch rate of InAs/GaSb T2SL was about three times slower than that of GaSb, and found to be limited by the slow etch rate on InAs.…”

GaAs and AlGaAs reactive ion etching in SiCl4/Ar gas mixtures for HEMT applications

“…Gases like Cl 2 , BCl 3 , CCl 2 F 2 e SiCl 4 (4,5,6), together with the diluents such as N 2 , O 2 , Ar e H 2 , are extensively used.…”