The Improvement Of Ammonia Corrosion On SOI Wafer Surface With Smart-Cut Technology

From Moore's law promoted,IC technology came to a higher ability on design and production.SOI(Silicon-On-Insulator),as the substrate choice of low power device,came to one of the main trend of the more Moore's law.The major kinds of process flow are SIMOX,SIMBOND,BESOI,Smartcut and so on.Smart-cut,as the combined of SIMOX and BESOI,comes to the promising method for SOI process.The ammonia corrosion in CMP process was troubling the process in the several years.The failure rate was near 1%-2% for whole production in the world level and 6% in China.This study found that ammonia corrosion was caused by the volatilization of slurry which storage in polish pad.After polishing operation finished,the volatile slurry from polish pad corroded the wafer surface and became corrosion layer.The study also found that with the polish pad life time lapses,the increasing of accumulated slurry in the pad will make the corrosion defect much obvious.Base on the research,the ammonia corrosion can be solved by increasing water polish time,reducing waiting time after main polish and decreasing the brush pressure.Through this optimization the corrosion defect quantity was reduced 600%,and monthly yield loss was controlled to minimal 0.13%.The mastery of this technology in China can reach the level of proficiency.