Investigation of Negative Bias Temperature Instability Effect in Partially Depleted SOI pMOSFET

Abstract

The negative bias temperature instability (NBTI) mechanisms for Core and input/output (I/O) devices from a 130 nm partially-depleted silicon on insulator (PDSOI) technology are investigated. The I/O device degrades more than the Core device under the same stress electric field due to the different gate oxide processes in these two types of devices. Both the oxide trap charge and interface trap lead to the transfer characteristics degradations of the device after NBTI. While the near interfacial traps result in the increase of low frequency noise (LFN). The trap densities near the silicon/gate oxide interface introduced by stress are extracted using the LFN method. NBTI-induced gate current increase is observed for Core device, but not for I/O device. It is result from the enhanced tunneling process, which is induced by the increase of electric field in the gate oxide after charge trapping at or near the channel interface. The gate width and length dependences of NBTI are observed. The enhanced NBTI degradation observed in short channel and narrow channel device is result from the enhanced NBTI effect at channel edge regions. The larger hole concentration is a main cause of the more serious NBTI degradation at the channel edge regions, including the nearby region of STI sidewall along the channel width direction and the gate edge region along the channel length direction. This conclusion is also verified by the TCAD simulations.

Keywords

• Low frequency noise
• negative bias temperature instability
• silicon on insulator
• TCAD simulation