The Etching of Crystallographically Determined Orifices in Sapphire

Reisman, Arnold; Berkenblit, M.; Zirinsky, S.; Chan, S. A.

doi:10.1149/1.2129163

Cited by 9 publications

(5 citation statements)

References 2 publications

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“…However, in our case, A1 oxidized preferentially to Si and the rate of silicon oxidation, when 50% of the wafer was uniformly masked with A1, was a factor of approximately three less than that of an unmasked silicon wafer. This behavior indicates a large sticking coefficient on the A1 of the oxidizing species and is reminiscent of epitaxial growth behavior on Ge and ZnO reported previously by one of the authors (7)(8)(9). However, when MgO was used as a mask material, exposed Si areas oxidized at the same rate as that of a blanket silicon wafer.…”

Section: Masking Studiessupporting

confidence: 77%

The Formation of SiO2 in an RF Generated Oxygen Plasma: II . The Pressure Range Above 10 mTorr

Ray

Reisman

1981

J. Electrochem. Soc.

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This paper describes the formation of SiO~ in an rf generated oxygen plasma in the pressure range above 10 mTorr. The experimental setup used for this study is the same as that described in Part I of this study. Using the silicon-mask interface as a marker and examining the cross section of silicon wafers after oxide formation, it was concluded that the mechanism of oxide formation in the pressure range 10-100 mTorr is growth of SiO2. A unique and unexpected result of the plasma process conducted at pressures greater than 10 mTorr is that oxide growth occurs primarily on the surface of the wafer facing away from the plasma, in sharp distinction to the observations made at pressures less than 10 mTorr where the oxide forms only on the surface facing the plasma. A key experimental parameter is the confinement of the plasma by the wafer which was observed only at pressures greater than 10 mTorr and at generator frequencies from 0.5 to 3 MHz. Oxide growth rate was studied as a function of pressure, power, frequency of the a~plied field, and substrate parameters to determine the optimum growth conditions. The etch rate, refractive index, stress, fixed charge, interface states, and breakdown strength of plasma oxides grown at 500~ compare very favorably to thermal oxides grown at ll00~ * Electrochemical Society Active Member.

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Section: Masking Studiessupporting

confidence: 77%

The Formation of SiO2 in an RF Generated Oxygen Plasma: II . The Pressure Range Above 10 mTorr

Ray

Reisman

1981

J. Electrochem. Soc.

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“…The geometrical pulse-to-pulse overlap (OL) in percent mentioned in the paper is defined here as [11,53] (equation ( 1))…”

Section: Methodsmentioning

confidence: 99%

“…In case of anisotropic etching of crystalline sapphire, differences in the etching rates of (main) crystal planes appear to be related to the atomic arrangement [52]. The anisotropic etchant used in this study, a mixture of sulphuric and phosphoric acid, is selected for its known property of etching sapphire anisotropically [53], by means of which crystallographically determined structures can be created on/in sapphire. Aota et al [38] discussed the main etching mechanisms of anisotropic etching of sapphire when using this mixture for surface-texturing of substrates.…”

Section: Crystallographic Structure and Anisotropic Etching Of Sapphirementioning

confidence: 99%

“…The presence of a patterned mask layer results in concave corner etching (figures 1(b1) and (b2)), regardless of the presence/absence of laser irradiated spots/areas on the surface. Concave corner anisotropic etching is obtained if the surface of the substrate is protected (for example by a hard mask) and inhibits convex corner anisotropic etching on rims and edges [48,53]. If no hard mask is present, the (flat) surface of sapphire etches uniformly, as indicated by the black arrows in figure 1(b3)).…”

Section: Crystallographic Structure and Anisotropic Etching Of Sapphirementioning

confidence: 99%

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Fabrication of microstructures in the bulk and on the surface of sapphire by anisotropic selective wet etching of laser-affected volumes

Capuano

Berenschot²,

Tiggelaar³

et al. 2022

J. Micromech. Microeng.

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In this paper a processing technique for sapphire is presented which combines laser-induced amorphization and subsequent selective wet etching of amorphized sapphire as well as anisotropic wet etching of single-crystalline sapphire (α-Al2O3). Using this technique, microstructures can be realized on the surface and in the bulk of sapphire substrates. By focusing ultra-short laser pulses inside sapphire, its structure can be transformed from crystalline into amorphous. The modified material can be selectively removed using etchants, such as hydrofluoric acid (HF) or potassium hydroxide (KOH), solely dissolving the amorphized part. In this work, however, an etchant consisting of a standard solution of sulphuric acid and phosphoric acid (96 vol% H2SO4 : 85 vol% H3PO4, 3:1 vol%) at 180 °C is utilized. This method allows the realization of structures which are impossible to achieve when using conventional etchants which solely dissolve the amorphized sapphire. Ultrashort pulsed laser irradiation (230 fs) is used in this study as starting point for the subsequent anisotropic etching to form microstructures on the surface or in the bulk of sapphire that are terminated by characteristic crystal planes. In particular, the appearance of etching-induced patterns formed by stacks of rhombohedra is shown for structures below the surface, whereas triangular pits are achieved in surface processing.

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“…A slightly modified version of the process described by Reisman et al [4] was used to micro-machine 12 µm thick membranes with several geometries in r-plane sapphire using a front-and backside mask [5].…”

Section: Tes Bolometer Fabricationmentioning

confidence: 99%

Performance of a far-IR TES bolometer on monolithic sapphire membrane

2004

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The performance of a high Tc (~90 K) transition-edge superconducting (TES) bolometer on a monolithic sapphire membrane is presented and discussed. It is compared to the performance of a previous TES bolometer on non-monolithic sapphire substrate. The development and optimization of monolithic sapphire membranes is critical for the fabrication of 1 and 2-D arrays of TES bolometers. Moderately cooled and optimized TES bolometers are expected to be the replacements of choice for thermopiles and other room temperature thermal sensors on far IR instruments on future planetary missions.

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The Etching of Crystallographically Determined Orifices in Sapphire

Cited by 9 publications

References 2 publications

The Formation of SiO2 in an RF Generated Oxygen Plasma: II . The Pressure Range Above 10 mTorr

The Formation of SiO2 in an RF Generated Oxygen Plasma: II . The Pressure Range Above 10 mTorr

Fabrication of microstructures in the bulk and on the surface of sapphire by anisotropic selective wet etching of laser-affected volumes

Performance of a far-IR TES bolometer on monolithic sapphire membrane

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