Photostimulated evaporation of SiO2 films by synchrotron radiation

Akazawa, Housei; Utsumi, Yuichi; Takahashi, Junichi; Urisu, Tsuneo

doi:10.1063/1.104167

Cited by 57 publications

(20 citation statements)

References 10 publications

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“…However, in previous studies using synchrotron radiation, direct etching at room temperature proved impossible, and it was necessary either to heat the workpiece [14-16, 19, 21] or to use reactive gases [12,17,18,20,22]. In the former case, the etching rate improves as the temperature is raised to about 700 °C [16,19,21]. Thus, etching of SiO 2 and Si is possible using synchrotron radiation.…”

Section: Micromachining Of Transparent Materialsmentioning

confidence: 96%

Ablation of silica glass induced by laser plasma soft X‐ray irradiation

Makimura

Fujimori

Torii

et al. 2011

Elect Comm in Japan

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SUMMARYSilica glass can be ablated using focused laser plasma soft X-rays. The ablation technique enables us to fabricate trenches with a width as narrow as 50 nm. In the present paper, we have investigated the nano-ablation process. The soft X-ray irradiation causes a silica surface broken into almost atomic species. Ionic species have kinetic energies higher than that gained by heating to the boiling point. We measured the ablation depth as a function of the soft X-ray fluence. The depth analysis revealed that soft X-rays are absorbed in a silica surface with an effective absorption depth of 10 nm. The result indicates that the energy density of the soft X-rays per unit volume at the threshold fluence is comparable to that required for breaking silica glass into atomic species. Further, the results suggest that ablation occurs before diffusion of absorbed energy into the surrounding region. In addition to energy absorption, repulsive forces between ionic species may cause ablation of the silica surface by soft X-ray irradiation. These properties of soft X-ray ablation may make possible the nano-ablation of silica glass.

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Section: Micromachining Of Transparent Materialsmentioning

confidence: 96%

Ablation of silica glass induced by laser plasma soft X‐ray irradiation

Makimura

Fujimori

Torii

et al. 2011

Elect Comm in Japan

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“…However, in the previous studies using synchrotron radiation, direct etching at room temperature proved impossible; it was necessary either to heat up the workpiece [14-16, 19, 21], or to use reactive gases [12,17,18,20,22]. In the former case, the etching rate improves as the temperature is raised up to about 700 °C [16,19,21], and an activation energy of 0.7 eV is needed [21]. The etching rate of SiO 2 is more than an order of magnitude lower than that of Si [24], and therefore crystalline Si can be used as a mask for SiO 2 etching [19,21].…”

Section: Introductionmentioning

confidence: 97%

“…In the former case, the etching rate improves as the temperature is raised up to about 700 °C [16,19,21], and an activation energy of 0.7 eV is needed [21]. The etching rate of SiO 2 is more than an order of magnitude lower than that of Si [24], and therefore crystalline Si can be used as a mask for SiO 2 etching [19,21]. On the other hand, SiO 2 can be etched even at room temperature if synchrotron light is applied in an atmosphere of SF 6 or some other reactive gas.…”

Section: Introductionmentioning

confidence: 98%

Micromachining of inorganic materials using plasma soft x‐rays

Makimura

Uchida

Fujimori

et al. 2008

Elect Comm in Japan

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SUMMARYWe have investigated nanomachining of inorganic materials using laser plasma soft X-rays. The soft X-rays were generated by irradiating Ta targets with pulsed Nd:YAG laser light. The laser plasma soft X-rays were focused using an ellipsoidal mirror, which is designed so as to focus soft X-rays at around 10 nm efficiently. The focused soft X-rays were incident to the surfaces of inorganic materials such as silica glass, LiF, CaF 2 , and LiNbO 3 . It is found that these materials are ablated by soft X-ray irradiation. In particular, silica glass can be ablated at rates of 0.2 to 150 nm/shot, which can be controlled by the intensity of soft X-rays. It is remarkable that silica can be ablated smoothly with a roughness of 1 nm after 10 shots of soft X-ray irradiation at a rate of 50 nm/shot. In order to demonstrate nanomachining of silica glass, we used contact masks on top of silica glass plates fabricated by electron beam lithography technique. The silica glass plates were irradiated with laser plasma soft X-rays through the windows of the contact masks. We found that nanofabrication of trenches with a width of 70 nm was performed clearly.

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“…It should be noted that the increase in the sample temperature T s may play a considerable role in desorption to enhance the etching rate for the synchrotron radiation processing, but would not take over the role of the X-ray photons in the dissociation. The Arrhenius-like plot for the etching rate [mm (100 mA) À1 min À1 ] gave a slope of 0.1 eV in our case for PTFE, smaller than 0.7 eV in the case of the synchrotron radiation direct photo-etching of SiO 2 (Akazawa et al, 1990), and much smaller than 3.6 eV, the activation energy for vacuum pyrolysis of PTFE (Single et al, 1964). As mentioned above, mass spectrometric analysis in the case of PTFE has also provided evidence that the dissociation of PTFE during the synchrotron radiation process is completely different from thermal dissociation.…”

mentioning

confidence: 99%

“…For synchrotron radiation, however, there have been few cases of the direct photo-etching process. The ®rst synchrotron radiation direct etching (termed`evaporation') was carried on SiO 2 by heating the sample to 1073 K (Akazawa et al, 1990). The etching rate increased signi®cantly with the temperature rise, but was very small (less than 7 Â 10 À3 mm min À1 ).…”

Section: Introductionmentioning

confidence: 99%

Synchrotron radiation direct photo-etching of polymers and crystals for micromachining

Katoh

Zhang

1998

J Synchrotron Radiat

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Synchrotron radiation etching of polymers and optical crystals which are transparent throughout the spectral range from visible to ultraviolet has been carried out without using any chemicals, successfully creating high-aspect-ratio microstructures for micromachining. A detailed study of the etching rates by varying the synchrotron beam current, sample temperature, beam size and aspect ratio showed that this synchrotron radiation process is essentially different from laser ablation, while an in situ mass spectrometric analysis of gaseous etching products showed that the dissociation mechanism involved with the synchrotron radiation processing, even with heating, is completely different from the thermal dissociation of the laser ablation.

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Photostimulated evaporation of SiO2 films by synchrotron radiation

Cited by 57 publications

References 10 publications

Ablation of silica glass induced by laser plasma soft X‐ray irradiation

Ablation of silica glass induced by laser plasma soft X‐ray irradiation

Micromachining of inorganic materials using plasma soft x‐rays

Synchrotron radiation direct photo-etching of polymers and crystals for micromachining

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