IDENTIFICATION AND REMOVAL OF TRACE ORGANIC CONTAMINATION ON SILICON-WAFERS STORED IN PLASTIC BOXES

As semiconductor device geometries continue to shrink, trace volatile organic contamination adsorbing on silicon surfaces has an increasingl y detrimental impact on product performance and yield. Therefore, it b ecomes important to identify the origin of the organic contaminants an d to eliminate them from the wafer. When wafers are stored in a plasti c box in order to protect them from airborne contaminants, volatile or ganics from the polymeric construction material adsorb onto the wafter surfaces. A very small quantity of additives in the plastic material are apt to adsorb onto the wafers more easily than the unpolymerized m onomers and oligomers outgassing in large quantities. As a result of t he evaluation of various wet cleaning solutions in terms of their abil ity to remove these trace organic contaminants, dilute HF as well as o zonized ultrapure water has been found to completely remove these orga nic contaminants adsorbing on the silicon surfaces. After wet cleaning , organic contaminants adsorb more easily on the ozonized water-treate d silicon surface than on the dilute HF-treated surface. Adsorption of the organic additives on the silicon surfaces can be inhibited by pre venting the native oxide growth in a nitrogen atmosphere after dilute HF cleaning. Possible explanations for these phenomena are considered.