Plasma damage reduction for high density plasma CVD phosphosilicate glass process

The high density plasma (HDP) CVD phosphosilicate glass (PSG) process applied on pre-metal dielectric layer has the plasma damage concern which can impact the device performance or reliability. A HDP CVD PSG process was developed to reduce the plasma damage and improve the electrical reliability by optimizing the process. The plasma damage was primarily monitored by corona-oxide-semiconductor (COS) charge measurements, and further, two advanced logic devices threshold voltage stability were tested. The COS results show the new improved HDP PSG process can obviously reduce the surface voltage (Vs), flat band voltage (Vfb) and interface trap density (Dit). The advanced logic device electrical reliability results also show significant reduction in Vt shifts for the improved HDP PSG process.