Etching characteristics of GaN by plasma chemical vaporization machining

Nakahama, Yasuji; Kanetsuki, Norio; Funaki, Takeshi; Kadono, M.; Sano, Yasuhisa; Yamamura, Kazuya; Endo, Kazuhiko; Mori, Yojiro

doi:10.1002/sia.2955

Cited by 11 publications

(7 citation statements)

References 16 publications

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“…It enables high-efficiency etching with high-density neutral radicals and does not induce plasma ion damage on the work surface owing to the low kinetic energy of ions. Moreover, this method has demonstrated a high etching rate on hard-to-process materials such as SiC and GaN, (7) although it has difficulties in flattening the surface efficiently owing to isotropic etching by neutral radicals. Aiming at a few hundreds of atoms inside the diamond surface…”

Section: Proposed High-efficiency Process: Basic Conceptmentioning

confidence: 99%

Novel Chemical Mechanical Polishing/Plasma-Chemical Vaporization Machining (CMP/P-CVM) Combined Processing of Hard-to-Process Crystals Based on Innovative Concepts

2014

Sensors and Materials

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In this research, we aim to establish systematic knowledge of ultraprecision processing of hard-to-process crystal wafers for next-generation "green devices", and design and develop a high-efficiency, high-quality process to contribute to an early commercialization of SiC, GaN, and diamond-based devices demanded for a low-carbon society. Upon designing an ultrahigh-precision process for hard-to-process materials, we divided the process into two steps: a pretreatment step and a finishing step. In the pretreatment step, a pseudoradical area was formed by introducing ultrafine defects to control the surface condition suitable for finishing. In the finishing step, we attempted to combine the closed-chamber chemical mechanical polishing (CMP) and plasma-chemical vaporization machining (P-CVM) methods. To evaluate the concept of the second step, a fundamental study needed to design and prototype the machine was conducted. As a method of creating a pseudoradical area, femtosecond (fs) laser irradiation and coarse processing (grinding), which leaves a crystallographically disordered layer, were considered. Microindentation test, cross-sectional transmission electron microscopy (TEM) observation, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and reflection high-energy electron diffraction (RHEED) were used to confirm the 404 Sensors and Materials, Vol. 26, No. 6 (2014) pseudoradical area at the uppermost surface. Also, we studied the characteristics of the pseudoradical substrates subjected to CMP and P-CVM. P-CVM showed an increased processing rate for the pseudoradical substrates having microdefects. It will be necessary to optimize the degree and depth of crystallographic disorder in the pseudoradical area in the future. On the basis of the results presented here, we are starting to prototype the innovative CMP/P-CVM combined processing machine, which can selectively flatten the nanotopographies of hard-to-process materials by conducting CMP and P-CVM while continuously creating a pseudoradical area through an in situ physical effect such as polishing.

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Section: Proposed High-efficiency Process: Basic Conceptmentioning

confidence: 99%

Novel Chemical Mechanical Polishing/Plasma-Chemical Vaporization Machining (CMP/P-CVM) Combined Processing of Hard-to-Process Crystals Based on Innovative Concepts

2014

Sensors and Materials

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“…Kim et al [7] studied the ablation of GaN by ultrashort pulsed laser, and successfully demonstrated the controlled ablation. Nakahama et al [8] used plasma chemical vaporization machining (CVM) to observe the etching characteristics of GaN and reached the conclusion that less subsurface damage is caused by plasma CVM than RIE (reactive ion etching). Zhang et al [9] conducted molecular dynamics simulation to investigate the mechanism of subsurface damage during nano grinding process of GaN and provided an insight into low-damage processing of GaN by the subsurface damage mechanism.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Orthogonal Machining of Gallium Nitride via Smoothed Particle Hydrodynamics

Haseeb

Saeed

Ghumman

2022

NIJEC

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Gallium Nitride is one of the best candidates for upcoming industrial revolution due to itssuperior electrical properties over silicon. In the present work, we investigate the chipformation, cutting force and effective stress in diamond machining of gallium nitride bysmoothed particle hydrodynamics approach based on Mohr-Coulomb material model. Thecomparison of the effective stress as reported by molecular dynamics studies and thatpredicted by the smoothed particle hydrodynamics simulation demonstrates the effectivenessof the smoothed particle hydrodynamics model.

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“…A damage-free processed surface can also be obtained because of the very low amount of ion energy in the plasma due to the short mean free path of gas molecules (about 0.1 µm). Using P-CVM, a high removal rate of more than 1 µm/min has been observed even for SiC (Sano et al, 2009) and GaN substrates (Nakahama et al, 2008). However, the P-CVM etching is isotropic, and there are no means to planarize the surface.…”

Section: Introductionmentioning

confidence: 99%

High-efficiency planarization method combining mechanical polishing and atmospheric-pressure plasma etching for hard-to-machine semiconductor substrates

Sano

Shiozawa

Doi

et al. 2016

Mechanical Engineering Journal

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A high-efficiency planarization technique for preprocessing before final polishing is needed for hard-to-machine wide-band-gap semiconductors, such as silicon carbide (SiC), gallium nitride, and diamond. We proposed a novel planarization method that combines chemical mechanical polishing (CMP) and atmospheric-pressure plasma etching (plasma chemical vaporization machining [P-CVM]) and developed a prototype of the basic type CMP/P-CVM combined processing system. This prototype has a mechanical polishing part for introducing a damaged layer on the convex part of the sample surface and a P-CVM part for efficient etching of the damaged layer. Process conditions for plasma generation were determined in order to minimize the optical emission intensity ratio of nitrogen to helium because nitrogen comes from circumstance air and should not exist in the plasma region. Process conditions for mechanical polishing were determined in order to efficiently generate a damaged layer only on the convex part of the sample surface. The combined process was performed using a SiC substrate on which the mesa structure was fabricated as a sample. As a result, we found that the convex parts of the mesa structure were preferentially removed and the surface of the sample was planarized. We also found that the decreasing rate of the peak-to-valley value of the mesa structure obtained by CMP/P-CVM combined processing was approximately seven times greater than that during mechanical polishing.

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Etching characteristics of GaN by plasma chemical vaporization machining

Cited by 11 publications

References 16 publications

Novel Chemical Mechanical Polishing/Plasma-Chemical Vaporization Machining (CMP/P-CVM) Combined Processing of Hard-to-Process Crystals Based on Innovative Concepts

Novel Chemical Mechanical Polishing/Plasma-Chemical Vaporization Machining (CMP/P-CVM) Combined Processing of Hard-to-Process Crystals Based on Innovative Concepts

Numerical Simulation of Orthogonal Machining of Gallium Nitride via Smoothed Particle Hydrodynamics

High-efficiency planarization method combining mechanical polishing and atmospheric-pressure plasma etching for hard-to-machine semiconductor substrates

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