Hk. Park et al., A PRACTICAL EXCIMER LASER-BASED CLEANING TOOL FOR REMOVAL OF SURFACE CONTAMINANTS, IEEE transactions on components, packaging, and manufacturing technology. Part A, 17(4), 1994, pp. 631-643
A laser-cleaning tool capable of removing surface contaminants such as
submicron-sized particulates and organic films has been constructed a
nd implemented in practical use. An industrial-grade KrF excimer laser
is utilized to irradiate the solid surface to be cleaned. The nanosec
ond-pulsed laser irradiation, shortly after the deposition of a thin l
iquid film on the surface, induces explosive vaporization of the liqui
d and removal of particulates (''steam cleaning''). The ultraviolet (U
V) irradiation also causes ablative photodecomposition of organic film
contaminants on the surface (''dry cleaning''). Hence, cleaning can b
est be done with the combination of these two laser-cleaning modes. Th
e excimer laser cleaning tool is constructed with an aim toward practi
cal use: It includes a computer-controlled laser beam scanning system
and a stable liquid film deposition unit, providing a cleaning rate of
over 200 cm(2)/min. Semiconductor, metal, and ceramic sample surfaces
, contaminated with 1-mu m sized alumina particles and micron-thick ep
oxy films, are tested by laser cleaning. The effectiveness of laser cl
eaning is compared with ultrasonic technique. The cleaning strategy an
d the probability of thermal damage due to laser cleaning are discusse
d.