Integrated downstream solutions for TEOS silicon dioxide LPCVD system

TEOS (tetraethylorthosilicate, Si(OC/sub 2/H/sub 5/)/sub 4/) has been a popular source material for chemical vapor deposition of silicon dioxide (SiO/sub 2/) thin films because of its excellent trench and via filling capability and high film quality. However, rapid clogging of the pumping foreline has been a major issue for a TEOS LPCVD process as it leads to lower system flow conductance and higher particle level. This, in turn, leads to higher maintenance requirement, longer downtime, and lower process yield. A new integrated solution has been developed at MKS to solve this problem. This includes a nitrogen Virtual Wall installed at the furnace exit to reduce the solid deposition and particle generation, and an efficient trap to protect the downstream devices such as valves and vacuum pump. By utilizing this integrated downstream solutions, we have extended the PM cycle more than 5X and reduced particle level by over 20%. In addition, quartz tube life doubles, roots pump life significantly increases, maintenance on throttling and isolation valves is reduced, the cleaning process is dramatically simplified, and maintenance costs are significantly reduced.