CCl 4 -based reactive ion etching of semi-insulating GaAs and InP (original) (raw)
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Reactive ion etching of GaAs using CCl2F2 and the effect of Ar addition
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1983
GaAs etching rate performed by RIE in CCl 2 F 2 gas has been shown to depend on many parameters: pressure, rfpower and flow rate. Moreover addition of Ar in CCI 2 F has been found • 2 to Increase the etch rate. This observation and the AES study of etched GaAs surfaces has led to the conclusion that volatile chloride species contribute to the etching mechanism, while fluoride species which are less volatile inhibit etching. Schottky diodes presenting an ideality factor of 1.02 have been fabricated on CCl 2 F 2 etched GaAs surface.
The Open Plasma Physics Journal
GaAs etch characteristics like etch rate, etch profile sidewall angle, etch surface morphology and selectivity are studied as a function of Inductively Coupled Plasma (ICP) power and Cl 2 /BCl 3 flow rate ratio in ICP at low pressure (<15mTorr) and low RF bias power (<100W) regime to achieve moderate GaAs etch rate with an-isotropic profiles and smooth surface morphology. The low pressure regime etching at Cl 2 /BCl 3 flow rate ratio of 4:1 has resulted in vertical etch profiles with controlled sidewall angle ~ 84º, smooth surface morphology and good mask selectivity ~15 without significant deposition of CCl x polymer on the etched sidewalls but with limited etch depth ~ 100μm using photoresist mask. The mask selectivity is found to be a strong function of RF bias power and ICP power and a weaker function of process pressure. The resultant etch depth increases with an increase in pressure and flow rate ratio at the expense of etch surface morphology, as the desorption of chemical species limits the etching process at higher Cl 2 flow rates and leaves some of the residue on the surface.
Journal of Applied Physics, 1995
The residual damage incurred to GaAs viaetching with a Cl,/Ar plasma generated by an electron cyclotron resonance (ECR) source was investigated as a function of variations in ion energy, ion flux, and etching temperature. The residual damage and electrical properties of GaAs were strongly influenced by changes in these etching parameters. Lattice damage was incurred in all processing situations in the form of small dislocation loops. GaAs etched at high ion energies with 200 W rf power, exhibited a defect density five times higher than GaAs etched at lower ion energies with 20 W rf power. This enhanced residual damage at the higher rf powers was paralleled by a degradation in the unannealed contact resistance. Higher etch rates, which accompany the higher rf power levels, caused the width of the disordered region to contract as the r-f power was elevated. Therefore, the residual etch damage is influenced by both the generationand removal of defects. Increasing the microwave power or ion flux resulted in elevating the residual defect density, surface roughness, and unannealed contact resistance. GaAs etched at high temperatures,-350 "C, resulted in a lower contact resistance than GaAs etched at 25 "C. The high temperature etching augmented the defect diffusion which in turn lowered the near surface defect density. This decrease in residual damage was deemed responsible for improving the electrical performance at 350 "C. The electrical measurements were found to be more sensitive to the density of defects than the vertical extent of disorder beneath the etched surface. Results of this investigation demonstrate that in order to minimize material damage and improve electrical performance, etching with an ECR source should be performed at low rf and microwave powers with a high substrate temperature. 0 I995 American Institute of Physics.
Microelectronic Engineering
We investigate the parameter optimization for micron-scale etching by Inductive Coupled Plasma-Deep Reactive Ion Etching (ICP-DRIE) of GaAs/AlGaAs semiconductor heterostructures. Although dry etching approaches have been reported in the literature using a broad variety of plasma etch tools, there is still need to meet the majority of microsystems dry etching requirements. The etch process family studied here, is dominated by the relative pressures of BCl 3 (Boron trichloride) and Cl 2 (Chlorine) gases. The influence of using a BCl 3 /Cl 2 / Ar/N 2 mixture at different pressures has been investigated: A small addition of N 2 (Nitrogen) is very effective inducing sidewall protection when using photoresist masks. The etch profile quality has been characterized as a function of the plasma process and of the etched feature sizes. The desired etch characteristics for GaAs/AlGaAs heterostructures can be achieved by controlling the various process parameters with good reliability, high selectivity, andsimultaneouslyhigh etch rates and sidewall verticality. Etch rates from 1 to over 5.5 μm/min have been obtained. The selectivity with optical photoresist varies from 2.3 to 16. The presented results can be valuable for a wide range of applications involving fabrication of micro-electro-mechanical-systems or Micro Optoelectronic Mechanical Systems.
The oxidation of surface layers during reactive ion etching of GaAs in CF2Cl2+O2 and O2 plasmas
Applied Surface Science, 1999
The RF plasma was created in a plasmatron system with accelerating potential of 20-700 V, discharge power of 0.5-5.0 Wrcm 2 and at pressure of 10 y4-10 y2 Torr. The thickness and composition of formed oxide layer is considered experimentally at various etching parameters: ion current density, plasma composition, substrate temperature. The experimental curves were modeled by proposed phenomenological model. The model includes the main processes taking place during reactive ion etching: sputtering, adsorption, heterogeneous chemical reactions, desorption of volatile compounds and radiation enhanced diffusion. The model gives the kinetics of elemental composition on the surface and the composition of the altered layer.
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
Vacuum, 2010
We have investigated the selective etching of 50 mm diameter via-holes for etch depth >200 mm using 30 mm thick photo resist mask in Inductively Coupled Plasma system with Cl 2 /BCl 3 chemistry. Resultant etch rate/etch profiles are studied as a function of ICP process parameters and photo resist mask sidewall profile. Etch yield and aspect ratio variation with process pressure and substrate bias is also investigated at constant ICP power. The etch yield of ICP process increased with pressure due to reactant limited etch mechanism and reached a maximum of w19 for 200 mm depth at 50 mTorr pressure, 950 W coil power, 80 W substrate bias with an etch rate w4.9 mm/min. Final aspect ratio of etched holes is increased with pressure from 1.02 at 20 mTorr to 1.38 at 40 mTorr respectively for fixed etch time and then decreased to 1.24 at 50 mTorr pressure. The resultant final etch profile and undercut is found to have a strong dependence on the initial slope of photo resist mask sidewall angle and its selectivity in the pressure range of 20e50mTorr.
Modeling of altered layer formation during reactive ion etching of GaAs
Applied Surface Science, 2012
The binary collision based SDTrimSP model has been used to simulate the reactive ion beam etching (RIBE) of GaAs in the presence of energetic Ar ions and thermal O atoms. It includes the collisional effects, diffusive processes and chemical reactions taking place in the system. The model parameters are fitted using the experimental observations of Grigonis [1] and validated with the experimental results obtained during the GaAs ion etching presented in this paper. A detailed analysis is presented to understand the effect of the diffusive processes and the role of O during RIBE of GaAs. It is shown how the presence of damage caused by the energetic Ar coupled with the presence of thermal O opens up chemical reaction channels which eventually leads to the preferential sputtering of Ga observed at the ion etching facility at University of Greifswald.