Physics Commons^™

Removal Versus Ablation In Krf Dry Laser Cleaning Of Polystyrene Particles From Silicon, Sergey I. Kudryashov, Susan D. Allen

Susan D. Allen

Direct absorption and melting of 0.2, 0.5 and 1.1 μm polystyrene particles on a Si substrate irradiated by 248 nm excimer laser radiation was found to contribute to their dry laser removal via a "hopping" mechanism at cleaning thresholds of 0.05, 0.1, and 0.16 J/cm ², respectively. Ablation of these particles, which starts near the beginning of substrate deceleration at fluences above 0.4-0.5 J/cm ², suppresses particle removal due to ablative recoil momentum. At fluences above a second cleaning threshold of 0.7 J/cm ² particles are completely evaporated without any visible surface damage of the Si substrate.

© …

Photoacoustic Study Of Krf Laser Heating Of Si: Implications For Laser Particle Removal, Sergey I. Kudryashov, Susan D. Allen

Susan D. Allen

A photoacoustic study of KrF laser heating of Si has revealed that the dominant mechanism of acoustic generation is thermoacoustic with a considerable contribution from the concentration-deformation mechanism at laser fluences below the Si melting threshold of 0.5 J/cm ². Upon Si melting the contraction of the molten material contributes significantly to acoustic generation. At fluences above 1.4 J/cm ² laser ablation of the molten layer enhances the amplitude of the compression pulse and diminishes that of the rarefaction pulse. The results of photoacoustic measurements allow optimization of experimental conditions for dry laser particle removal.

© 2002 American Institute …

Optical Transmission Measurements Of Explosive Boiling And Liftoff Of A Layer Of Micron-Scale Water Droplets From A Krf Laser-Heated Si Substrate, Sergey I. Kudryashov, Susan D. Allen

Susan D. Allen

Water plume velocities were measured in air by optical transmission as a function of laser fluence using a KrF laser for explosive boiling and liftoff of a layer of micron-scale waterdroplets from a laser-heated Si substrate of interest for laser particle removal. The thickness of the superheated water layer near the water/Si interface determines acceleration and removal of the waterdroplets from the Si substrate.

© 2003 American Institute of Physics

Analysis Of Adsorbed Contaminants Of Caf2 Surfaces By Infrared Laser Induced Desorption, Jinmei Fu, Yamini Surapaneni, Susan D. Allen

Susan D. Allen

157 nm photolithography technologies are currently under development and have been accepted as the leading candidate for fabrication of the next generation semiconductor devices after 193 nm. At this and shorter wavelengths, molecular contamination of surfaces becomes a serious problem as almost all molecules absorb at 157 nm and below. The light transmitted by a photolithographic tool can be significantly decreased by the presence of a few monolayers adsorbed on its many optical surfaces. We have developed a laser induced desorption, electron impact ionization, time-of-flight mass spectrometer (LID TOFMS) to study contaminants on 157nm and other ultraviolet optics, e.g., polished …

Parametric Generation Of Multimegahertz Acoustic Oscillations In Laser-Generated Multibubble System In Bulk Water, Sergey I. Kudryashov, Kevin Lyon, Susan D. Allen

Susan D. Allen

Using a nanosecond C O2 laser for explosive surface boiling of bulk water, oscillatory acoustic transients from steam bubbles were recorded using a contact photoacoustic technique. Multiple well-resolved, high-amplitude multimegahertz spectral features reflecting parametric interactions between oscillations of cavitating steam bubbles were revealed in the fast Fourier transformation spectra of these transients. A potential parametric generation mechanism for these oscillation modes of steam bubbles is discussed.

© 2006 American Institute of Physics.