H. Morinaga et al., BEHAVIOR OF ULTRAFINE METALLIC PARTICLES ON SILICON-WAFER SURFACE, Journal of the Electrochemical Society, 142(3), 1995, pp. 966-970
The diameter of particles which adversely affects the yield has been s
hrinking as ULSI devices are more and more miniaturized. Ultrafine par
ticles with diameters of 0.1 mu m or less have become important recent
ly. Ultrafine particles of this type are expected to be difficult to r
emove. This study has established a method to evaluate ultrafine parti
cle removal efficiency. Ultrafine metallic particles with diameters of
several to several hundreds of nanometers were deposited on the Si su
rface using a gas deposition method. The removal efficiency of the ult
rafine particles using various cleaning solutions was investigated. AP
M (NH4OH-H2O2-H2O) cleaning can remove 150 nm Au particles, but cannot
remove ultrafine Au particles with a diameter less than several tens
of nanometers. In addition, the Si surface becomes rougher when a DHF-
H2O2 cleaning is performed to remove Au ultrafine particles. This is b
elieved to be because noble metals such as Au, Ag, and Cu, which featu
re a higher electronegativity than Si, attract electrons from Si facil
itating Si oxidation.