Analysis of GaN etching damage by capacitively coupled RF Ar plasma exposure

Kawakami, Retsuo; Inaoka, Takeshi; Minamoto, Shingo; Kikuhara, Y.

doi:10.1016/j.tsf.2007.08.019

Cited by 36 publications

(40 citation statements)

References 13 publications

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“…However, in the case of Ar plasma, the AlGaN surface profile was roughened significantly. The AlGaN surface profile etched with Ar plasma was similar to that observed for n-GaN etched with Ar plasma [8][9][10]. This indicates that the change in the AlGaN surface profile was related to UV light irradiation from the Ar plasma.…”

Section: Resultssupporting

confidence: 71%

“…The gas pressure of the plasma was varied between 10 and 100 mTorr. The duration of the plasma etching was varied from 5 to 100 min [8]. The spectrum of the ultraviolet (UV) light emitted from the plasmas was measured using a visibleultraviolet spectrometer (Ocean Optics, USB4000).…”

Section: Methodsmentioning

confidence: 99%

“…However, the mechanism and the related surface damage are not yet known. Previously, we investigated the effect of Ar plasma etching on n-GaN surfaces [8][9][10]. We reported that surface roughening clearly occurs in n-GaN by a synergistic effect between UV light irradiation from the plasma and ion bombardment of the sample surface [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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Surface Analysis of AlGaN Treated with CF<sub>4 </sub>and Ar Plasma Etching

Hirai

Niibe

Kawakami

et al. 2015

e-J. Surf. Sci. Nanotech.

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To understand the surface damage of AlGaN film caused by plasma etching in detail, we etched AlGaN film with CF4 and Ar plasmas. The intensity of ultraviolet (UV) light emitted from the CF4 plasma was very weak at each gas pressure investigated. However, in the case of Ar, a certain degree of UV intensity was observed at gas pressures between 50 and 100 mTorr. The surface etched with the CF4 plasma was as smooth as that of the as-grown film. In the case of Ar, surface roughening occurred at gas pressures between 50 and 100 mTorr. The Al/N and Ga/N ratios of the AlGaN surface etched with Ar plasma increased more significantly than those of the surface etched CF4 plasma, as determined by X-ray photoelectron spectroscopy (XPS). The peak shape of the near-edge X-ray absorption fine structure (NEXAFS) spectra in the N-K absorption edge was broadened by the plasma etching with increasing processing-time. The broadening observed in the case of Ar etching was greater than that during CF4 plasma etching. The observed changes in the surface morphology and crystalline structure of the AlGaN are considered to be caused by the synergistic effect of UV light irradiation from the plasma and ion bombardment of the sample surface. The changes in surface composition, surface roughening, and the disordering of the crystalline structure were found to occur within a shallow region from the surface, and did not occur in deeper regions of the sample. F atoms (ions) were found to penetrate the surface to a depth of about 10 nm in the AlGaN etched with CF4 plasma.

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Section: Resultssupporting

confidence: 71%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Surface Analysis of AlGaN Treated with CF<sub>4 </sub>and Ar Plasma Etching

Hirai

Niibe

Kawakami

et al. 2015

e-J. Surf. Sci. Nanotech.

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“…This happens because there is a similarity between the Xe and Ar plasma etching surface damages: the formation condition of surface defect by the Xe plasma etching is almost similar to that by the Ar plasma etching [4]. Namely, for the Xe and Ar plasma etchings, the surface defect tends to be formed at the high gas pressure and long etching time (for 50 mTorr, at more than 100 min or at least 200 min there occurs the synergy effect).…”

Section: Etch Surface Damage and Modificationmentioning

confidence: 98%

“…Until nowadays, GaN etch surface damage/modification by capacitively coupled RF Ar and Kr plasmas has been studied by the authors, in order to clearly elucidate the correlation between the discharge plasma behavior and the surface damage/modification properties [4][5][6][7]. That study clarified a fascinating result: for the Ar plasma etching, there are many types of defects or pits on the etched surface, whereas for the Kr plasma etching, there is no defect on the etched surface, which is almost similar to that of the as-grown GaN surface.…”

Section: Introductionmentioning

confidence: 99%

Synergy Effect of Xenon Plasma Ions and Ultraviolet Lights on GaN Etch Surface Damage and Modification

Kawakami

Inaoka

Tominaga

et al. 2011

Trans. Mat. Res. Soc. Japan

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Surface damage/modification of n-GaN by Xe plasma etching has been investigated for a variety of gas pressures and etching times, using an experiment and a simulation. The result has been compared with that for the Kr plasma etching. The surface morphology etched by the Xe plasma is dependent on gas pressure and etching time. At a low gas pressure (10 mTorr), where there is no UV light emission from the plasma, the surface morphology is observed to be as smooth as that of the as-grown surface, and is independent of etching time. At a high gas pressure (50 mTorr), where there is the UV radiation emission resulting from XeII, there are defects on the etched surface when the etching time increases (200 min), which would probably result from synergy effect of the Xe plasma ions and UV radiations. This result is significantly different from that etched by the Kr plasma which does not change from that of the as-grown surface. The simulation also shows that the Ga/N ratio at the surface etched by the Xe plasma is lower than that by the Kr plasma, which would be related to the difference between the surface morphologies by these two plasmas.

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Neutral beam etching for device isolation in AlGaN/GaN HEMTs

Hemmi

Clifford

Lai

et al. 2016

Physica Status Solidi (a)

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In this article, we report a suppression of leakage current and an improvement of isolation breakdown voltage on GaN‐based high electron mobility transistors (HEMTs) by means of neutral beam (NB) etching. The plasma damage during dry etching process is one of the key reasons for an isolation leakage current, gate leakage current, and current collapse in GaN HEMTs. Since NB etching is virtually free from electrical charges and has few UV photons, it is possible to reduce plasma damage on an etched surface and improve device characteristics. In this work, we introduced NB etching to the device isolation process of GaN HEMTs and characterized isolation leakage currents at DC and step‐stress bias conditions. We also measured the breakdown voltages on two‐terminal test element arrays. We compared the characteristics with samples etched by conventional plasma‐like beam (PB) etching. Our results suggest that NB etching reduces the leakage current through the etched surface of the mesa isolation, which results in superior breakdown voltages.

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Analysis of GaN etching damage by capacitively coupled RF Ar plasma exposure

Cited by 36 publications

References 13 publications

Surface Analysis of AlGaN Treated with CF<sub>4 </sub>and Ar Plasma Etching

Surface Analysis of AlGaN Treated with CF<sub>4 </sub>and Ar Plasma Etching

Synergy Effect of Xenon Plasma Ions and Ultraviolet Lights on GaN Etch Surface Damage and Modification

Neutral beam etching for device isolation in AlGaN/GaN HEMTs

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