Chemical dry etching of GaAs and InP by Cl2 using a new ultrahigh-vacuum dry-etching molecular-beam-epitaxy system

Furuhata, Naoki; Miyata, Hiroshi; Okamoto, Akihiko; Ohata, K.

doi:10.1063/1.342564

Cited by 52 publications

(19 citation statements)

References 10 publications

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“…[1][2][3][4] In contrast, little is known about the evolution of surface roughness during the etch. It was found early on by optical microscopy that the thermal chlorine etch leads to a smooth surface at a substrate temperature of 300°C, but at a lower (150°C) or higher temperature (500°C) the substrate becomes rough 5 . Scanning tunneling microscopy studies of GaAs͑110͒ surfaces show that halogen etching proceeds by formation of one layer deep etch patches.…”

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confidence: 99%

Kinetic roughening of GaAs(001) during thermalCl2etching

et al. 2002

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The surface morphology of Cl 2 -etched GaAs͑001͒ is measured as a function of etch time by atomic force microscopy and elastic light scattering. A flat surface is found to become rougher during the etch whereas a textured substrate becomes smoother. We have numerically simulated this behavior. It is found that the evolution of surface roughness at length scales between 50 nm and 5 m can be described with excellent accuracy by a continuum equation for the surface height h(x ជ ,t), which is given by dh/dtϭٌ 2 h Ϫ/2(ٌh) 2 ϪKٌ 4 hϩ, where is a random noise input.Typical processes in nanofabrication involve the patterning of surfaces by various etching techniques, and deposition or regrowth of thin films on these patterned substrates to create three-dimensional nanostructures. In the etching process, atoms on the surface chemically react and form volatile etch products. The chemical reactions and the removal of the etch products from the surface are inherently random processes, which are subject to fluctuations on the atomic scale. Surface roughness at mesoscopic length scales created by these fluctuations sets an ultimate limit to the precision with which nanostructures can be fabricated by chemical etching processes. It is, therefore, of great fundamental and practical importance to gain a quantitative understanding of this process.The reaction of GaAs͑001͒ with molecular chlorine is one of the most widely studied and employed etching processes. In recent years, much progress has been made in understanding the adsorption of halogens on semiconductor surfaces and in identifying the main reactions that are taking place on the surface. 1-4 In contrast, little is known about the evolution of surface roughness during the etch. It was found early on by optical microscopy that the thermal chlorine etch leads to a smooth surface at a substrate temperature of 300°C, but at a lower (150°C) or higher temperature (500°C) the substrate becomes rough 5 . Scanning tunneling microscopy studies of GaAs͑110͒ surfaces show that halogen etching proceeds by formation of one layer deep etch patches. 6 In this work, we report a quantitative description of the etched surface morphology using a continuum etch equation. In this approach, the discrete nature of the atoms on the surface is averaged out and the surface height is taken to be a continuous function h(x ជ ,t) whose time rate of change can be related to various spatial derivatives of h. Possible terms that can be included in a continuum equation have been derived within the framework of kinetic roughening theory. 7-9 Generally, in the limit of long times and large length scales, these equations lead to surfaces with characteristic scaling properties, and most experimental studies to date have concentrated on determining the relevant scaling coefficients for a given system. However, a sufficiently wide range of time and length scales to obtain reliable scaling exponents is often not accessible experimentally. In this work we demonstrate that the comparison of numerical simulations of...

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Kinetic roughening of GaAs(001) during thermalCl2etching

et al. 2002

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“…Here we suppose, that at an elevated temperature of 200°C the chlorides are not only removed by argon ions, but also desorb thermally. 8,13 Because of a small argon ion current in this experiments the CGE process presumably dominates. In this temperature regime the etch process is desorption limited and AsCl 3 desorbs faster than GaCl 3 which causes a rough surface.…”

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confidence: 98%

Characterization of in situ etched and molecular beam epitaxy regrown GaAs interfaces using capacitance–voltage measurements, far infrared spectroscopy, and magnetotransport measurements

Klein¹,

Kramp²,

Beyer³

et al. 2000

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…The reaction of GaAs with C12 has been studied previously using plasma [1], thermal- [3,7,8], ion- [2][3][4][5][6], and laser-excitation [9][10][11][12] to enhance the etching process. Those studies have led to a description of the etching mechanism that begins with a rapid chlorination of the surface, followed by a slower process in which the surface is more fully chlorinated.…”

Section: Etching Mechanismmentioning

confidence: 99%

“…This bottleneck can be overcome in a number of ways permitting etching to continue. Plasmas [1], bombardment by ion beams [2][3][4][5][6], thermal excitation [3,7,8], and laser excitation [9][10][11][12] have all been used to enhance the etching reaction. Laser-assisted etching with other chlorine containing species has also been observed [9,13].…”

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Laser-assisted etching of gallium arsenide in chlorine at 308 nm

Berman¹

1991

Appl. Phys. A

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Abstract. Xenon chloride (308 nm) excimer laser-assisted etching of GaAs (100) in C12 was demonstrated and characterized with respect to laser and gas parameters. The etch rate increased linearly with laser fluence from thresholds in the range of 50 to 75 mJ/cm 2 to the highest fluence studied, 650 mJ/cm 2. For a laser fluence of 370 mJ/cm 2, the etch rate varied with C12 pressure reaching a maximum at a C12 pressure of about 2 Torr. The etch rate decreased monotonically with Ar buffer gas pressure because of redeposition of GaC13 products into the etched channel. The redeposited GaC13 affected the etch rate and the etch morphology. The etch rate and morphology also varied with laser repetition rate. The mobility of chlorine on the surface also plays an important role in the etching mechanism.PACS: 81.60.C, 82.65.Y, 82.50The reaction of GaAs with C12 is often used in the anisotropic dry etching of GaAs. At room temperature, this reaction self-terminates almost immediately by forming a surface layer of GaC13 and negligible etching occurs. This bottleneck can be overcome in a number of ways permitting etching to continue. Plasmas [1], bombardment by ion beams [2-6], thermal excitation [3,7,8], and laser excitation [9][10][11][12] have all been used to enhance the etching reaction. Laser-assisted etching with other chlorine containing species has also been observed [9,13]. In excimer laser-assisted etching, deposition of chlorine onto the surface takes place at low substrate temperatures, while removal of etching products occurs during the short time in which the surface interacts with the laser pulse. Excimer laser-assisted etching can be used for projection or mask etching, and it avoids ion-induced damage to the GaAs lattice observed following irradiation by ion beams [14].Excimer laser-assisted etching of GaAs by chlorine has been previously studied with excitation at 193 and 248 nm [10,11]. In the present work, the etching reaction has been studied with 308-rim excitation from a XeC1 excimer laser. Comparing studies at different wavelengths helps determine the role of photon energy and photochemistry in the laser-assisted etching mechanisms. The use of longer wavelength irradiation in etching might also lessen damage to masks and other materials. In these experiments, etch rates were measured over a wide range of laser ftuence, Cla and buffer gas pressure, and laser repetition rate. Laser-assisted etching with chlorine was compared with laser ablation, the former displaying a much lower laser fluence threshold. This demonstrates the importance of the production of products that can easily be vaporized or otherwise removed by the laser pulse. Redeposition of etch products into the etched region was also determined to significantly affect both the etch rate and the etch morphology.

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Chemical dry etching of GaAs and InP by Cl2 using a new ultrahigh-vacuum dry-etching molecular-beam-epitaxy system

Cited by 52 publications

References 10 publications

Kinetic roughening of GaAs(001) during thermalCl2etching

Kinetic roughening of GaAs(001) during thermalCl2etching

Characterization of in situ etched and molecular beam epitaxy regrown GaAs interfaces using capacitance–voltage measurements, far infrared spectroscopy, and magnetotransport measurements

Laser-assisted etching of gallium arsenide in chlorine at 308 nm

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