<i>In situ</i> monitoring of electron cyclotron resonance plasma processing of GaAs surfaces by optical reflection spectroscopy

Weegels, L. M.; Saitoh, Tadashi; Oohashi, H.; Katô, Hiroshi

doi:10.1063/1.111484

Cited by 10 publications

(6 citation statements)

References 12 publications

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“…[1][2][3][4][5] This method also holds promise in other technological processes where the cleanness of the surface or interface is of critical importance, e.g., in deposition of thin metal or dielectric films and an ion implantation. The atomic hydrogen cleaning has made it possible to obtain, under the conditions of ultrahigh vacuum, an atomically clean and atomically smooth surface showing a high degree of structural perfection and suitable for growing high-quality epitaxial layers.…”

Section: Introductionmentioning

confidence: 99%

In situ cleaning of GaAs and AlxGa1−xAs surfaces and production of ohmic contacts using an atomic hydrogen source based on a reflected arc discharge

Kagadei

Proskurovsky

1999

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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A method for the production of ohmic contacts to n-type GaAs and to n-type and p-type AlxGa1−xAs has been proposed where the surface cleaning in atomic hydrogen and the metal film deposition are performed in situ. A feature of the method is that it is realized in a system for vacuum deposition of metal films with the residual pressure kept equal to ∼5×10−4 or ∼(4–10)×10−5Pa when GaAs or AlxGa1−xAs structures, respectively, are cleaned. The atomic hydrogen flow was formed by a source whose operation is based on a reflected arc discharge with a hollow cathode and a self-heating electrode. In the process of cleaning the hydrogen pressure was 10−2 Pa and the temperature of the specimens and the time of their treatment were varied in the ranges from 300 to 400 °C and from 1 to 90 min, respectively. AuGe/GaAs interfaces with the contaminant content below the sensitivity threshold of the method of Auger electron spectroscopy (AES) have been produced. With some technological expedients, an AuGe/Al0.6Ga0.4As interface with the oxygen content <1% and the contents of other impurities below the sensitivity threshold of the AES method have been produced. A comparative investigation of the formation of an ohmic contact by the proposed method and by a conventional technology using “wet” chemical cleaning has shown that the contacts produced with the use of atomic hydrogen cleaning show a better morphology of the surface and a more even edge of the contact pad, high adhesion of the metal film to the semiconductor, and a low contact resistance. The technological process for the production of ohmic contacts is characterized by a high reproducibility. The application of the proposed method together with hydrogenation of the near-surface region of semiconductor structures used in the production of light diodes have raised the output power of the diodes by 30%–40%.

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Section: Introductionmentioning

confidence: 99%

In situ cleaning of GaAs and AlxGa1−xAs surfaces and production of ohmic contacts using an atomic hydrogen source based on a reflected arc discharge

Kagadei

Proskurovsky

1999

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…1 Weegels et al observed large changes in the in situ reflectivity spectrum during room temperature hydrogen ECR etching with bias, 13,14 which they interpreted with a model that had a damage layer containing amorphous and crystalline GaAs. Their results for Ar etching, like ours, showed much less change in critical point structure than the room temperature hydrogen etching.…”

Section: Gaas Etchingmentioning

confidence: 99%

Spectroscopic ellipsometric monitoring of electron cyclotron resonance plasma etching of GaAs and AlGaAs

Snyder

Ianno

Wigert

et al. 1995

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

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In situ real time spectroscopic ellipsometry measurements were made during electron cyclotron resonance plasma etching of radio frequency biased GaAs and AlGaAs samples. Gas mixtures used were CH 4 /H 2 /Ar, pure H 2 , and pure Ar. Ellipsometry provided information about damage to the surface region and AlGaAs epilayer thickness. For the methane mixture GaAs etch, damage appeared in the form of redshifted and broadened E 1 and E 1 ϩ⌬ 1 critical point features in a surface layer several tens of nm thick. The damage layer began forming within a few seconds after the start of etching, and stabilized within 1 min. Hydrogen etching caused a thicker damage layer with greater redshifting and broadening, while argon caused relatively little damage. Possible mechanisms for the redshifting are discussed. During etching of an AlGaAs/GaAs heterostructure with the methane mixture, the same redshifting and broadening effects were seen in the AlGaAs critical point structure. The AlGaAs thickness was determined from the real time data, from which an etch rate of about 20 nm/min was derived.

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“…Previously, we have demonstrated that this is a fast and highly sensitive technique for assessing the damage to and the alteration of the semiconductor surface during ECR plasma processing. 16 In particular, distinct differences were found between physical sputtering by argon ions and chemical cleaning by hydrogen ions. Here we investigate the cleaning process as a function of temperature and interpret our experiments by fitting a three-phase ambient-overlayer-substrate model to the experimental results.…”

mentioning

confidence: 99%

“…All spectra are normalized to the response of the surface just before plasma exposure. During plasma exposure the holder is negatively biased with respect to the vacuum chamber at Ϫ7.5 V. It is estimated that the kinetic energy of the ions is less than 30 eV at a flux of 5ϫ10 16 ions s Ϫ1 cm Ϫ2 .…”

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confidence: 99%

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Real-time investigations of GaAs surface cleaning with a hydrogen electron cyclotron resonance plasma by optical reflection spectroscopy

Weegels

Saitoh

Katô

1994

Applied Physics Letters

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The composition changes during GaAs oxide removal and the subsequent cleaning with a hydrogen electron cyclotron resonance plasma have been investigated with real-time optical reflection spectroscopy. It is found that the oxide is not completely removed at low temperatures, resulting in a thick damaged surface region. At moderate temperatures (300–500 °C) the plasma exposure is characterized by a two-step process: a removal of the native oxide in a few seconds followed by a gentle etch of the GaAs. In the latter step the plasma exposure leads to a surface region with little damage to the crystal.

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In situ monitoring of electron cyclotron resonance plasma processing of GaAs surfaces by optical reflection spectroscopy

Cited by 10 publications

References 12 publications

In situ cleaning of GaAs and AlxGa1−xAs surfaces and production of ohmic contacts using an atomic hydrogen source based on a reflected arc discharge

In situ cleaning of GaAs and AlxGa1−xAs surfaces and production of ohmic contacts using an atomic hydrogen source based on a reflected arc discharge

Spectroscopic ellipsometric monitoring of electron cyclotron resonance plasma etching of GaAs and AlGaAs

Real-time investigations of GaAs surface cleaning with a hydrogen electron cyclotron resonance plasma by optical reflection spectroscopy

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