Superpolishing sapphire: A method to produce atomically flat and damage free surfaces

Hader, B.; Weis, O.

doi:10.1016/0039-6028(89)90466-4

Cited by 23 publications

(6 citation statements)

References 2 publications

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“…Aniline is an excellent probe molecule because its resonance enhanced two-photon laser ionization ͑REMPI͒ spectroscopy is accessible with simple laser dye mixtures. [9][10][11][12][13] Sapphire is an ideal insulator surface because it can be superpolished 14 to a very uniform flat surface and maintains a chemically homogeneous surface of hydroxyl groups. 15 Laser-induced thermal desorption has numerous applications and has been extensively studied; 16 however, few studies have explored the transfer of energy as desorbed molecules make the transition from surface-bound to gas-phase species.…”

Section: Introductionmentioning

confidence: 99%

Evidence for thermalization of surface-desorbed molecules at heating rates of 108 K/s

Maechling

Clemett

Engelke

et al. 1996

The Journal of Chemical Physics

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Articles you may be interested inOn the mechanism of C60 thin film laserinduced desorption Discharge flowtube studies of O(3 P)+N2H4 reaction: The rate coefficient values over the temperature range 252-423 K and the OH(X 2Π) product yield at 298 K Resonant laser ionization of thorium using continuous thermal heating and pulsed laser evaporation AIP Conf.Laser desorption of aniline-d7 from a single-crystal surface ͑0001͒ of sapphire ͑Al 2 O 3 ͒ at a heating rate on the order of 10 8 K/s was studied using pulsed infrared laser radiation for desorption and resonance enhanced multiphoton ionization ͑REMPI͒ for detection of the desorbed aniline molecules. On the basis of single-vibronic-level fluorescence ͑SVLF͒ spectra we unambigiously assign the 10b transition. REMPI spectroscopy provides vibrational temperatures and therefore describes the internal energy distribution, whereas the time-of-flight ͑TOF͒ profiles provide translational temperatures. All results are consistent with a thermal mechanism for desorption, i.e., pulsed heating of the sapphire surface on the nanosecond time scale leads to thermal desorption and rapid thermalization of the escaping molecules.

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Section: Introductionmentioning

confidence: 99%

Evidence for thermalization of surface-desorbed molecules at heating rates of 108 K/s

Maechling

Clemett

Engelke

et al. 1996

The Journal of Chemical Physics

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“…The effects of pH value on MRR and surface roughness were also discussed by other researchers (15)(16)(17)(18)(19)(20). It was agreed that higher MRR could be achieved in CMP of c-plane sapphire when the slurry pH value was over 10 regardless what type of slurry was used.…”

Section: Advances In Materials Removal Mechanismmentioning

confidence: 66%

“…It can be seen that MRR increases with the increase of pad rotation speed. Hader and Weis also studied the effects of pad rotation speed on MRR in CMP of c-plane sapphire (15). They found that there existed an optimal value for pad rotation speed.…”

Section: Pad Rotation Speedmentioning

confidence: 99%

An Overview of Recent Advances in Chemical Mechanical Polishing (CMP) of Sapphire Substrates

Zhang

Lin

2013

ECS Trans.

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Nowadays, sapphire substrates are widely employed for GaN light emitting diodes (LEDs) due to their comparatively low cost, large diameter, high quality, optical transparency, and high temperature stability etc. However, in spite of its commercial importance and extended history, the machining of sapphire remains a challenge. In the manufacture of sapphire, chemical mechanical polishing (CMP) has been widely used to obtain a mirror surface on the sapphire substrate and minimize the subsurface damages. In this paper, published literature in the past decade on CMP of sapphire substrates is summarized. Recent investigations into material removal mechanism of CMP of sapphire substrates are introduced and advances in experimental studies are reviewed in terms of abrasives, sapphire crystal orientations, pad materials, and other process parameters (such as polishing pressure, pad rotational speed, and temperature etc.). Possible topics for future research are also discussed.

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“…As Sapphire is extremely difficult to machine making delicate the realization of high-quality optical devices, one will also find interest in the accurate determination of the fluence levels required to modify the surface of Sapphire under a wide range of laser exposure conditions. Otherwise, the last step of fabrication of an optical component, consisting in the preparation of the material surface to provide the optics with optimal optical properties, is essential 9–11 . Indeed, the initial conditions of the surface, such as the roughness, topography and chemical and geometrical structure (contaminants, lattice deformation, inclusions), may have an influence on the absorption of the laser light, acting as absorption precursor or enhancement factor.…”

Section: Introductionmentioning

confidence: 99%

Importance of surface topography on pulsed laser-induced damage threshold of Sapphire crystals

Bussière

Sanner

Sentís

et al. 2017

Sci Rep

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We measure the laser-induced damage threshold (LIDT) fluence under single shot at the surface of Sapphire samples prepared following the standards of two methods yielding to different surface finish and used in optical and laser industry. We use AFM microscopy to measure the roughness parameter Ra and power spectral density (PSD) of the sample surface. We show that the quality of surface topography resulting from surface preparation affects the damage threshold of Sapphire crystals exposed to femtosecond, picosecond, and nanosecond laser conditions at visible and near-infrared wavelengths. We observe a higher resistance to laser damage or macroscopic modification when the surface finish presents a smooth and regular topography. We indeed measure a 1.4 to 2 times increase of the LIDT fluence in femtosecond and picosecond regimes and up to 5 times with nanosecond pulses. Using simple damage model and PSD data, we correlate the LIDT reduction of Sapphire samples of lower quality of surface finish with the high-frequency tail component of their PSD distribution corresponding to striations of the width of a fraction of the laser wavelength. This study emphasizes the importance of detailed assessment of surface topography for laser damage evaluation and understanding and for indicating directions of improvement.

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Superpolishing sapphire: A method to produce atomically flat and damage free surfaces

Cited by 23 publications

References 2 publications

Evidence for thermalization of surface-desorbed molecules at heating rates of 108 K/s

Evidence for thermalization of surface-desorbed molecules at heating rates of 108 K/s

An Overview of Recent Advances in Chemical Mechanical Polishing (CMP) of Sapphire Substrates

Importance of surface topography on pulsed laser-induced damage threshold of Sapphire crystals

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