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8 April 1996 Beam optimization for dry cleaning processes
Todd E. Lizotte, Orest P. Ohar, Thomas J. Baker, Terence R. O'Keeffe
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Alternative cleaning and surface preparation methods have been gaining interest recently because of the restrictions on the use of chlorofluorocarbons, their inability to clean contaminants less than 0.5 micron in size, water and chemical consumption and the hazardous waste disposal. These factors have also led to economic hardships to US manufacturers who have to compete on a global scale with countries not currently imposing environmental restrictions. Work on an Excimer Laser based cleaning process has been looked at for some time. In 1991, Allen and Tam1 used this DUV laser in conjunction with water or isopropyl alcohol to create a hydrostatic shock, formed by extreme heating of this liquid. This shock would scatter the contaminant along the surface. Although useful, it had an inherent drawback in that it lacked preferential directionality and could re-contaminate cleaned areas. Engelsberg has demonstrated that using DUV photons in combination with an inert laminar flowing gas provides the directionality needed for the removal of surface contaminants. This is known as the Radiance ProcessSM. The process does not cause underlying molecular structure damage of the bulk material and it is a competitive cleaning process from both a pricing and speed perspective. The actual mechanism behind the Radiance ProcessSM is unclear. A contaminant is held to the surface by a number of bonds which include covalent, ionic, hydrogen, electrostatic, dipole-dipole or Van der Waals.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Todd E. Lizotte, Orest P. Ohar, Thomas J. Baker, and Terence R. O'Keeffe "Beam optimization for dry cleaning processes", Proc. SPIE 2703, Lasers as Tools for Manufacturing of Durable Goods and Microelectronics, (8 April 1996);

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