Failure of reflective metal coatings by cracking

Zito, Richard R.

doi:10.1016/0040-6090(82)90575-2

Cited by 14 publications

(5 citation statements)

References 10 publications

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“…Single-shot direct laser ablation of 248 nm Cr film on fused silica substrate resulted in rupture of the Cr film at low fluence followed by melting and vaporization for increasing fluence [20]. Thermal cycling in air (293 to 594 to 293 K in 1 h) of 100-nm Cr film on soda-lime glass resulted in crack nucleation [21].…”

Section: Materials Alteratons In Nanofilms Under Thermomechanical mentioning

confidence: 98%

Onset of Material Alterations Due to Laser-Induced Plasma Exposure in Nanofilms Deposited on Photomasks

Varghese

Zhou

Peri

et al. 2009

IEEE Trans. Semicond. Manufact.

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Damage-free removal of sub-100 nm particles from photomasks with deposited nanofilms is a challenge in lithography. Laser-induced plasma (LIP) is an emerging noncontact, chemical-free, dry, and selective nanoparticle removal technique. Investigation of the onset of material alterations on bonded nanofilms for optimizing LIP particle removal process is the objective of this paper. Shockwave thermomechanical excitation and radiation heating from the plasma core are major potential sources of damage. Computational analyses reported here indicate radiation heating as the chief damage source. Damage thresholds for the critical nanofilm surface temperature rise and radial stress component have been identified for a given nanosecond pulsed laser.Index Terms-Cleaning of thin films, damage threshold, material alteration, nanofilm, nanoparticle removal, photomasks, radiation intensity from LIP, shockwave.

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Section: Materials Alteratons In Nanofilms Under Thermomechanical mentioning

confidence: 98%

Onset of Material Alterations Due to Laser-Induced Plasma Exposure in Nanofilms Deposited on Photomasks

Varghese

Zhou

Peri

et al. 2009

IEEE Trans. Semicond. Manufact.

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“…In general, damage is more probable in metal nanofilms compared to silicon wafers and substrates under thermal loading as thin metal films on substrates are more sensitive to rapid thermal loads. Cracks and nucleation of cracks have been observed on 100 nm chromium ͑Cr͒ film on soda-line glass when thermally cycled in air from 293 to 594 K, and then cooled back to 293 K in 1 h. 10 Thermal loading and consequent thermal expansion of thin films in nanosecond pulses is considered a probable source of damage concern for substrates with films. Mosaic patterned cracks, peeling-off, melting, and partial/complete removal has also been observed on thin Cr films under excimer laser ablation.…”

Section: Introductionmentioning

confidence: 99%

Thermal loading of laser induced plasma shockwaves on thin films in nanoparticle removal

Varghese

Zhou

Peri

et al. 2007

Journal of Applied Physics

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Damage concerns, such as substrate/film material alterations, damage, and delamination of thin films, have become a central problem in sub-100 nm particle removal applications. In the laser induced plasma (LIP) removal technique both LIP shockwave and radiation heating are potential sources of thermomechanical damage. The specific objective of current study is to conduct a computational investigation of the LIP shockwave effect on the thermoelastic response of a thin chromium (Cr) film deposited on a quartz substrate and to identify the conditions leading to the onset of plastic film deformations. The experimentally characterized shockwave pressure and temperature (approximated from gas dynamic relations) were prescribed as boundary conditions in the computational analysis. From the shockwave arrival times for different travel distances, the shockwave radius as well as the velocity were obtained as a function of the shockwave propagation time. Radial (and circumferential) stresses, caused by thermal expansion of the Cr film, were most dominant and, hence, of damage concern. It is determined that the resultant temperature rise utilizing a 1064 nm Nd:yttrium-aluminum-garnet (YAG) laser (450 mJ) due to the film-shockwave interactions was not sufficiently high to initiate film and/or substrate damage. No material alteration/damage of the Cr film is predicted due to the temperature and pressure of LIP shockwaves at the firing distance of 2 mm, with a high strain rate gain factor of two (minimum), though damage was observed experimentally for 1064 nm Nd:YAG laser at the pulse energy of 370 mJ. Reported results indicate that the leading cause of observed thin film damage during nanoparticle removal is almost certainly radiation heating from the LIP core.

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“…The alpha emissions from radioactive polonium-210 (half life 'r =138.3763 days = 1.2x107 sec) emerge with considerable energy, 210Po -> 206Pb (stable) + a (5.30 MeV) , (1) and some of these a particles are capable of spanning the gap between the ion-air gun nozzle and the surface to be cleaned. Range calculations for a particles can be difficult, but fortunately polonium-210 is an even-even member of the uranium series.…”

Section: Calculationsmentioning

confidence: 99%

Ion-air gun cleaning of substrates prior to thin film deposition

Zito

2005

SPIE Proceedings

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It is a common practice to give cleaned mirror substrates, and other optical surfaces, a final "dusting" with high pressure N2, or air, just prior to deposition of thin reflective coatings. The object of this procedure is to remove any particles that may have settled on the substrate since chemical cleaning and washing. Some types of "guns" used for blowing dust off a surface work well. However, other types, such as those containing a radioactive polonium source, can charge the substrate so that it attracts even more dust. In this report, the connection between electrostatic charge on a substrate and its dust "gettering" (dust collecting) ability is established. Also, test results are presented for the charging and discharging capabilities of various types, and manufacturers, of dusting guns.

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Failure of reflective metal coatings by cracking

Cited by 14 publications

References 10 publications

Onset of Material Alterations Due to Laser-Induced Plasma Exposure in Nanofilms Deposited on Photomasks

Onset of Material Alterations Due to Laser-Induced Plasma Exposure in Nanofilms Deposited on Photomasks

Thermal loading of laser induced plasma shockwaves on thin films in nanoparticle removal

Ion-air gun cleaning of substrates prior to thin film deposition

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