Effects of electron cyclotron resonance etching on the ambient (100) GaAs surface (original) (raw)
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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.
High-rate electron cyclotron resonance etching of GaAs via holes
Materials Science and Engineering: B, 2000
We report a high-rate etching of GaAs via holes using Cl 2 /Ar plasma generated by an electron cyclotron resonance system. Ni, with a thickness of 200 nm, was used as the etch mask. The effects of the chuck temperature, process pressure, r.f. power, gas flow rate, and microwave power on the etch rate and the resultant etch profiles were investigated. The GaAs etch rate was found to increase as the process pressure, Cl 2 flow rate, and the r.f. power or the microwave power increased. An etch rate as high as 6.7 mm min − 1 was observed from a sample etched using a microwave power, r.f. power and process pressure of 800 W, 150 W and 50 mTorr, respectively. An etch profile, suitable for monolithic microwave integrated circuits via hole applications, has been achieved using the process developed.
Etching of GaAs(100) with Aqueous Ammonia Solution: A Synchrotron-Photoemission Spectroscopy Study
The Journal of Physical Chemistry C, 2010
Etching of the GaAs(100) surface with aqueous ammonia solution is studied by highly surface-sensitive synchrotron-radiation photoemission spectroscopy. It is shown that such treatment effectively removes the native oxide layer leaving the surface covered with elemental arsenic, as well as arsenic hydroxides AsOH and As(OH) 3 , gallium hydroxide GaOH, and gallium suboxide Ga x O. After annealing of the surface at 500°C
Applied Physics Letters, 1998
Photoreflectance has been used to study the electronic properties of (100) GaAs surfaces exposed to a Cl2/Ar plasma generated by an electron cyclotron resonance source and subsequently passivated by P2S5. The plasma etch shifts the Fermi level of p-GaAs from near the valence band to midgap, but has no effect on n-GaAs. For ion energies below 250 eV, post-etch P2S5 chemical passivation removes the surface etch damage and restores the electronic properties to pre-etch conditions. Above 250 eV, the etch produces subsurface defects which cannot be chemically passivated. Auger electron spectroscopy shows that etching increases As at the GaAs/oxide interface, while passivation reduces it.
The Journal of Physical Chemistry C, 2008
The interaction of the oxide-free GaAs(100) surface with acidic (HCl + 2-propanol) and basic (aqueous NH 3 ) solutions is studied by synchrotron-photoemission spectroscopy. It is found that both solutions attack mostly surface gallium atoms and form weakly soluble gallium chlorides and soluble gallium hydroxides, respectively. Thereby, Ga-As bonds at the surface are broken, and elemental arsenic is left behind on the GaAs surface. In addition, adsorbed 2-propanol molecules are observed on etching with HCl + 2-propanol solution, but no adsorbed water molecules are detected on etching with aqueous ammonia solution.
Reconstruction dependence of the etching and passivation of the GaAs(001) surface
JETP Letters, 2010
The methods of the layer by layer or "digital" etching of crystals, which makes it possible to control lably remove monolayers of a crystal and to maintain the atomic smoothness of the surface, have been actively developed in the last two decades. The cre ation of heterostructures for nanoelectronic investiga tions requires not only the layer by layer growth but also layer by layer etching of semiconductors. The dry (gas phase) etching methods such as reactive ion and ion beam etchings, which are widely used in the tech nology of the production of semiconducting struc tures, do not provide the control of etching at the atomic level. The layer by layer etching of III-V semiconducting compounds can be implemented by using adsorbates selectively reacting with atoms of group III or V.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1991
Electron cyclotron resonance (ECR) discharges are characterized by low ion energies (515 eV) and high densities of active species. This makes them excellent candidates for high rate, low damage dry etching of III-V semiconductors. We have investigated the use of ECR discharges of CH,/H,/Ar for etching InP, InGaAs, AlInAs and GaAs as a function of additional rf biasing of the sample, and in this article present the InP results. In contrast to the results with conventional reactive ion etching (RIE), ECR discharges lead to very shallow (-20 A) damaged layers on these materials and much less disruption of the electrical quality of the etched surface. For example, RIE of InP leads to nonstoichiometric, In-rich surfaces to which one cannot make a Schottky contact. Removal of at least 150 A of material is required before the integrity of the surface is restored. We have been able to achieve excellent rectifying contacts on ECR-etched InP without the need for wet chemical treatment of the surface. Optical and chemical analysis of the ECR etching shows that it clearly is a Low damage process relative to the more conventional dry etch methods.