Impact of reducing shallow trench isolation mechanical stress on active length for 40nm n-type metal-oxide-semiconductor field-effect transistors

We report an improved densification annealing process for sub atmospheric chemical vapor deposition (SACVD)-based shallow trench isolation (STI) to enhance n-type metal-oxide-semiconductor field-effect transistor (nMOSFET) performance for 40nm node and beyond. Experimental results show that this improved STI densification process leads to lower compressive stress in the small active area compared with the standard STI process. This is beneficial to electron mobility and leads to an enhancement of on-current (I_ON). Moreover, comparable drain induced barrier lowering (DIBL) and subthreshold swing (SS) characteristics for both devices indicate that the improved densification process would no significant influences on process variations or dopant diffusions. Hence, the improved STI process can be adopted in 40nm complementary metal-oxide-semiconductor (CMOS) technology and beyond.