Impact of Organic Contamination on Thin Gate Oxide Quality

The impact of organic contamination on the quality of 5-nm-thick gate oxide structures, both before and after gate oxidation, is studied. Sources of organic contamination are chemical surface modification (i.e. hexamethyldisilazane priming), wafer box storage and extended vacuum exposure. Gate oxide integrity is evaluated electrically. The origin and/or nature of the organic contamination is seen to have different effects on the electrical breakdown. Care should be taken when exposing silicon wafers to organic contamination prior to processing. Especially when contamination occurs at the SiO2/polysilicon interface, i.e. prior to a non-oxidizing process step, organics can be extremely deleterious.