High aspect ratio etching of GaSb/AlGaAsSb for photonic crystals (original) (raw)
Inductively Coupled Plasma Etching in ICl and IBr-Based Chemistries. Part I: GaAs, GaSb, and AlGaAs
Plasma Chemistry and Plasma Processing, 2000
High-density plasma etching of GaAs, GaSb, and AlGaAs was performed inICl/Ar and IBr/Ar chemistries using an Inductively Coupled Plasma (ICP)source. GaSb and AlGaAs showed maxima in their etch rates for both plamachemistries as a function of interhalogen percentage, while GaAs showedincreased etch rates with plasma composition in both chemistries. Etchrates of all materials increased substantially with increasing rf chuckpower, but
Materials Science and Engineering B-advanced Functional Solid-state Materials, 1997
This paper reports results of an investigation of the behaviour of several etchants in revealing structural defects in Al-, Te-, Cdand Te/Cd-doped GaSb. Etchants previously suggested for GaSb, as well as two etchants developed for GaAs and InP, were tested and modified in an attempt to establish the best conditions under which a given etchant may be used and what defects it is likely to reveal. Both the solutions consisting of H,O,-H,SO, and 3%Br-methanol provided reproducible etch figures on dislocations, the former on the (11 l)Ga, (11 l)Sb, (100) and (110) planes, and the latter only on the (1 I l)Ga plane. In contrast, H,O,-HCl and HCl-HN03-H,O did not perform satisfactorily in revealing dislocations in the analyzed samples. Using permanganate etchant, it was possible to observe growth striations only in the n-type GaSb. The CrO,-HF solution revealed growth striations on both the p-type and the n-type GaSb as well as defects formed due to constitutional supercooling. A new etchant. based on ceric sulfate, was developed to delineate growth striations along the Te-doped GaSb crystals. 0 1997 Elsevier Science S.A.
Fabrication of photonic crystal structures by focused ion beam etching
2004
Two methods for Focused Son Beam (FIB) etching of Photonic Crystal are presented. The first is a FIB-alone approach which is a very rapid, maskless process. This method has the disadvantage that it produces poor sidewall verticality, which leads to high losses in slab waveguide based systems. A sccond approach uses FIB to etch a metal mask layer, this is followed by RIE of a S O z layer and a final ICP etch of the SnP layer. Results show much improved sidewall verticality. Photonic crystals (PCs) are currently of considerable interest in applications as wide ranging as sensors to telecommunications. They are now being manufactured in large volumes by a number of research groups and companies around the world [I]. The techniques used in this manufacture have, thus far, been confined to either optical or e-beam lithography and some form of dry etching, in particular Reactive Ion Etching (RIE), Chemically Assisted Ion Beam Etching (CAIBE) and Inductively Coupled Plasma (ICP) etching [Z]. This usually involves lengthy exposure times and at least one mask transfer process. Focused Ion Beam (FIB) etching however, enables "direct write" photonic crystals to be formed with design of mask to manufactured device of 2 hours or less. The FIB etching process involves directing a beam of highly focused GaC ions at a sample surface under computer control. The surface is then ablated by the Ga' ions leaving a relief pattern. This ability is almost material independent, with only the etch rate and profiles changing with material. It is this speed and flexibility that makes this process particularly attractive. Unfortunately, there are disadvantages to this approach in particular, due the nature of FIB etching, it is very difficult to obtain good side wall verticality in holes and as will be discussed below, this leads to increased losses [3]. In order to overcome this problem a multistage approach is being adopted whereby FIB is used to define a top metal mask layer and then more traditional RIE and ICP etch steps are used to transfer the mask into a slab waveguide structure. Although this reduces the speed and flexibility of the approach, it is still felt that the high resolution obtainable with FIB etching and the lack of problems such as proximity effects could make FIB based PC fabrication a viable alternative to E-beam based methods. This paper presents results for fabrication and measurement of FIB-alone based PCs and then shows preliminary fabrication results for a multistage FIB based method. If a series of points are defined at regular intervals it is possible to form a photonic crystal structure by focused ion beam etching a typical structure is shown in Fig 1 . The photonic Crystal has been etched into a 3 layer slab guide structure such that light can be guided through the PC region in order to perform transmission tests on the device. ,f
A Comparison of Dry Plasma and Wet Chemical Etching of GaSb Photodiodes
Journal of The Electrochemical Society, 2004
We report on the performance of GaSb pn junction photodiodes fabricated using electron cyclotron resonance plasma etching using Cl 2 /Ar recipe, a mixed gas recipe consisting of Cl 2 /BCl 3 /CH 4 /Ar/H 2 and wet chemical etching. Diodes fabricated using Cl 2 /BCl 3 /CH 4 /Ar/H 2 recipe show an order of magnitude lower leakage current density and lower ideality factor. The highest value of the zero bias dynamic resistance-area product was obtained for Cl 2 /BCl 3 /CH 4 /Ar/H 2 etched diodes and was equal to 830 ⍀ cm 2 as compared to 300 ⍀cm 2 for Cl 2 /Ar and 330 ⍀ cm 2 for wet etching. Spectral responsivity of Cl 2 /BCl 3 /CH 4 /Ar/H 2 etched diodes was observed to be three times that of Cl 2 /Ar and wet etched diodes. Overall, the diodes etched using the recently reported Cl 2 /BCl 3 /CH 4 /Ar/H 2 recipe provided the best optical and electrical characteristics.
The etching characteristics of Al x Ga 1Ϫx N grown by metal-organic chemical-vapor deposition were investigated in an inductively coupled plasma ͑ICP͒ reactive ion etching system using Cl 2 /Ar gas mixtures. Etch rate variations with substrate bias voltage, ICP coil power, chamber pressure, Cl 2 /Ar gas mixture ratios, and gas flow rates were investigated. The optimum chamber pressure for etching was found to be dependent on both the substrate bias voltage and ICP coil power. Auger electron spectroscopy analysis showed that the stoichiometries of the etched Al 0.22 Ga 0.78 N surfaces were identical, independent of the etching conditions. Etching results were successfully applied to form highly anisotropic and smooth facets in GaN/InGaN/AlGaN heterostructure laser materials.
Inductively Coupled Plasma Reactive Ion Etching of GeSbTe Thin Films in a HBr/Ar Gas
Integrated Ferroelectrics, 2007
Inductively coupled plasma reactive ion etching of GeSbTe (GST) thin films with a photoresist mask was performed using a HBr/Ar gas mixture. The etch rate of GST films increased up to 20% HBr concentration and began to decrease with further increase of HBr concentration. The etch profiles were improved with increasing HBr gas concentration. In particular, clean and vertical etch profiles were achieved at 80∼100% HBr gas concentrations. As the coil rf power and dc-bias voltage increased, the etch rates increased. The gas pressure had little influence on the etch rate. The good etch profiles were obtained at high coil power, low dc-bias and high gas pressure. The x-ray photoelectron spectroscopy analysis reveals that Te showed highest reactivity with HBr gas chemistry. A high degree of anisotropic etching of GST films was achieved using HBr/Ar gas mixture at the optimized etch conditions.
Etching characteristics of Al2O3 thin films in inductively coupled BCl3/Ar plasma
Vacuum, 2008
The investigation of Al 2 O 3 etch characteristics in the BCl 3 /Ar inductively coupled plasma was carried out in terms of effects of input process parameters (gas pressure, input power, bias power) on etch rate and etch selectivity over poly-Si and photoresist. It was found that, with the changes in gas pressure and input power, the Al 2 O 3 etch rate follows the behavior of ion current density while the process rate is noticeably contributed by the chemical etch pathway. The influence of input power on the etch threshold may be connected with the concurrence of chemical and physical etch pathways in ion-assisted chemical reaction.
Inorganic Materials, 2017
⎯This paper presents results on the kinetics and mechanism of the physicochemical interaction of InAs, InSb, GaAs, and GaSb semiconductor surfaces with (NH 4) 2 Cr 2 O 7-HBr-C 4 H 6 O 6 etching solutions under reproducible hydrodynamic conditions in the case of laminar etchant flow over a substrate. We have identified regions of polishing and nonpolishing solutions and evaluated the apparent activation energy of the process. The surface morphology of the crystals has been examined by microstructural analysis after chemical etching. The results demonstrate that the presence of C 4 H 6 O 6 in etchants helps to reduce the overall reaction rate and extend the region of polishing solutions.
Etching characteristics of LiNbO3 crystal by fluorine gas plasma reactive ion etching
Science and Technology of Advanced Materials, 2001
The etching characteristics of a LiNbO 3 single crystal have been investigated using plasma reactive ion etching (RIE) with a mixture of CF 4 /Ar/H 2. The etching rate of LiNbO 3 with the mixture of CF 4 /Ar/H 2 gases was evaluated. The etching surface was evaluated by atomic force microscopy, X-ray diffraction and X-ray photoelectron spectroscopy methods. The rate-determining process of RIE is the supply of F radicals in RIE. The surface morphology of the etched LiNbO 3 changed with the increase in the H 2 gas¯ow ratio. The surface pro®le becamē at, on optimizing the etching conditions, similar to the surface of non-etched LiNbO 3. The X-ray diffraction peak for etched LiNbO 3 using the mixture of CF 4 and Ar gases did not appear, because a non-crystalline layer was formed. It was found that the crystallinity of the surface is dependent on both, the¯ow rate of H 2 gas and the etching time. F atoms exist in the contamination layer of the sample etched, using the mixture of CF 4 , Ar and H 2 gases. Optimum etching conditions, considering both the surface¯atness and the crystallinity, were determined.
Study of wet and dry etching processes for antimonide-based photonic ICs
Optical Materials Express, 2019
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.