Chemical Mechanical Polishing of Gallium Nitride with Colloidal Silica

Aida, Hideo; Koyama, Koji; Katakura, Haruji; Sunakawa, Kazuhiko; Doi, Toshiro

doi:10.1149/2.024112jes

Cited by 79 publications

(91 citation statements)

References 18 publications

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“…We achieve a macroscopically as well as atomically smooth surface, when the Ga-polar surface was polished with a silica based slurry after mechanical polishing. 13 polishing, ≈250 μm were removed to create an even surface. Afterwards, the surface features such as hillocks and facets were removed, but pits with reduced diameter are left, as their depth exceeds the thickness of the removed layer.…”

Section: Resultsmentioning

confidence: 99%

LEDs on HVPE grown GaN substrates: Influence of macroscopic surface features

et al. 2014

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We demonstrate the strong influence of GaN substrate surface morphology on optical properties and performance of light emitting devices grown on freestanding GaN. As-grown freestanding HVPE GaN substrates show excellent AFM RMS and XRD FWHM values over the whole area, but distinctive features were observed on the surface, such as macro-pits, hillocks and facets extending over several millimeters. Electroluminescence measurements reveal a strong correlation of the performance and peak emission wavelength of LEDs with each of these observed surface features. This results in multiple peaks and non-uniform optical output power for LEDs on as-grown freestanding GaN substrates. Removal of these surface features by chemical mechanical polishing results in highly uniform peak wavelength and improved output power over the whole wafer area.

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Section: Resultsmentioning

confidence: 99%

LEDs on HVPE grown GaN substrates: Influence of macroscopic surface features

et al. 2014

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“…The observation of the surfaces by these methods, however, does not guarantee a damage-free surface. (14) To evaluate the atomic arrangement of the surface, a certain type of diffraction method [e.g., reflection highenergy electron diffraction (RHEED)] must be utilized. Although RHEED can confirm the surface atomic arrangement, the usage of high vacuum impedes the high throughput.…”

Section: Issues In Wafer Processing Techniquesmentioning

confidence: 99%

Ammonothermal Bulk GaN Growth and Its Processing

2014

Sensors and Materials

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In this paper, we overview the current progress of ammonothermal GaN growth at SixPoint Materials, Inc. and discuss issues in wafer processing. Bulk GaN crystals grown in small prototype reactors present a high-quality microstructure as well as an improved transparency. The dislocation density of the crystal is on the order of 4.0 × 10 4 cm −2 . The optical absorption coefficient as low as 4 cm −1 at 450 nm is obtained. Wafer processing techniques, such as wire sawing and chemical mechanical polishing, are one of the challenges in realizing GaN wafers. Crystal cracks are the major and fundamental obstacle in achieving a high-quality surface during wire sawing. The surface quality after chemical mechanical polishing (CMP) is successfully evaluated using X-ray diffraction.

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“…Figure 11 shows time-dependent microscopy images of a GaN surface during colloidal silica polishing after diamond polishing as reported by Dr. Aida. (32) As shown in this figure, it took more than 100 h to obtain the final smooth surface, which is more than 100 times longer than in the case of Si. In GaN wafer polishing, more scratches appear even after the first layer of scratches vanishes.…”

Section: Wafer Processing Of Ganmentioning

confidence: 88%

“…This article reviewed innovative nonpolar/semipolar GaN devices, which will drive the demand for bulk GaN substrates, and discussed the current issues in manufacturing GaN substrates, focusing on substrate size expansion, growth method of bulk GaN, and processing of GaN wafers. (32) and (b) photographs of two-terminal GaN Schottky diode for gas sensing applications (packaged device). (33) (a) (b)…”

Section: Discussionmentioning

confidence: 99%

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Current Status and Future Prospects of GaN Substrates for Green Devices

2013

Sensors and Materials

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Recently, single-crystal substrates applied to optoelectronic devices, such as sapphire, GaN, and SiC, have been attracting much attention for use in green devices. At present, they are mainly used for the blue-violet semiconductor laser that is applied as the light source of Blu-ray disc equipment. In the near future, it is highly likely that they will be introduced into white LEDs used for lighting and LCD backlight, power transistors to be used for power converters, and also into power semiconductors such as power diodes, leading to the rapid growth of the green device market involving GaN, SiC and diamond. These single-crystal substrates are expected to serve as a trigger to realize a low-carbon and low-energy society, complying with the projected cutbacks of power and CO 2 emission by 70 billion kWh and 40 million tons per year, respectively. This is why they are referred to as "green devices". In this paper, we will discuss the recent approaches that are in progress to develop new devices, taking GaN substrates as an example. Furthermore, we will review current problems and future perspectives for the most critical issue of realizing large substrates, as well as for the crystal growth method and manufacturing process that affect crystal quality.

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Chemical Mechanical Polishing of Gallium Nitride with Colloidal Silica

Cited by 79 publications

References 18 publications

LEDs on HVPE grown GaN substrates: Influence of macroscopic surface features

LEDs on HVPE grown GaN substrates: Influence of macroscopic surface features

Ammonothermal Bulk GaN Growth and Its Processing

Current Status and Future Prospects of GaN Substrates for Green Devices

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