Influence of organic contamination on silicon dioxide integrity

The influence of organic contamination before oxidation on 8-nm-thick silic on dioxide integrity was studied. Contamination results from the intentiona l adsorption of dioctyl phthalate (DOP) on silicon wafers. Metal-oxide semi conductor (MOS) capacitors were fabricated on the wafers to measure the ele ctrical characteristics of the oxide. A reduction in the dielectric breakdo wn field strength of the oxide was found to occur after DOP adsorption of m ore than 1 x 10(13) mol/cm(2). The flat-band voltage shift (Delta V-fb) and interface trap charge density (D-it) increased with an increase in the amo unt of DOP below 1 x 10(13) mol/cm(2) Positive charges arose from DOP in th e oxide during oxidation, which was determined from a negative Delta V-fb. Furthermore, with an increase in the DOP level from 1 x 10(13) to 1 x 10(15 ) mol/cm(2), D-it hardly increased whereas a Delta V-fb gradually increased . This suggests that positive changes at the silicon-oxide interface are fi xed. It is thought that an increase in the amount of positive charge in the oxide reduces the dielectric breakdown voltage. From infrared (IR) adsorpt ion measurement, we found that even after DOP decomposition due to oxidatio n, positive charges within DOP remained, and they degrade oxide integrity.