Study of wet and dry etching processes for antimonide-based photonic ICs

Abstract

We report on the dry etch process parameters and the associated etch rates for target and mask materials, as well as surface roughness in an inductively coupled plasma (ICP) for the (AlGaIn)(AsSb)-compounds. The essential chemistry is based on Cl 2 with the addition of N 2 for sidewall passivation. The optimized ICP etch process is capable of producing high aspect ratio structures with smooth sidewalls. In situ reflectance monitoring with a 670-nm-wavelength laser was used to enable stop-etching at a material interface with high accuracy. Given the additional need for highly selective wet chemical etchants in the fabrication of GaSb based electronic and optoelectronic devices, an extensive investigation was also performed to examine numerous etch solutions. These etchants were listed with etch rates, selectivities, and surface roughness in order to validate their suitability for intended applications. Despite the frequent use of GaSb or InAsSb materials for etch stop layers against each other, devices where their unique type-II broken bandgap alignment is undesired require new selective wet etchants between GaSb and AlGaAsSb with good selectivity. All of the wet chemical and dry etching processes described here were optimized using an n-type GaSb substrate.

Design of GaSb-based monolithic passive photonic devices at wavelengths above 2 µm

“…When it comes to waveguides, the GaSb material system is fully transparent at λ > 2 µm, confirming low material absorption [5]. The latter requires a vertical-etch profile and smooth sidewall which could be achieved by the recent advancement of dry-and wet-etch processes in this material system [7].…”

Interband Cascade Photonic Integrated Circuits on Native III-V Chip

“…Reference [ 66 ] reviews the relatively advanced status of InP-based photonic integrated circuits operating at shorter wavelengths in the near IR, which can now combine numerous optical elements on a chip. Although GaSb-based PICs and GaSb-based device fabrication, in general, are much less mature [ 67 ], the simplest on-chip sensing configurations described above do not require methods especially more challenging than those already used routinely to process shortwave-IR and mid-IR lasers and detectors on GaSb. After patterning a large number of PICs on a die, individual sensors can be singulated to form a package that is both extremely compact and inexpensive.…”

Fabrication of Differently Shaped Polymeric Nanoneedle Arrays via Multistep Plasma Etching Using Silica Microparticles as Masks

“…Top‐down approaches using plasma etching systems such as radio frequency (RF) plasma, direct current (DC) plasma, and inductively coupled plasma (ICP) are well‐established technologies in the field of micro/nanofabrication. By starting with the fabrication of simple or irregularly shaped/patterned structures based on hard materials such as metals, semiconductors, and oxides, fabrication of complex structures became possible 1–3 . The advancement in hard material‐based nanostructure fabrication has enabled the prosperity of the electrical and semiconductor industries.…”