Electrothermal Effects on Hot Carrier Injection Reliability of n-Type FinFETs in Ring Oscillators

The hot carrier injection (HCI) reliability of n-type FinFETs in ring oscillators (ROs) is investigated with consideration of the circuit-level time-varying electrothermal effects in the ROs. The oscillating voltages and electrical power in a nine-stage RO are captured by circuit simulation in Cadence with its layout that is designed and verified based on FreePDK15. Spatial temperature response is obtained by heat conduction simulation with finite element analysis in the 3-D integrated structure that is accordingly constructed from the layout of the RO, where the heat generation is extracted from the Cadence simulation. With the obtained ac stress voltages and transient temperature, the HCI-induced threshold voltage shift (TVS) of n-type FinFETs under the circuit-level time-varying electrothermal effects is successfully predicted. The impacts of electrical and thermal parameters of the RO, including the supply voltage and thermal surrounding, on the electrothermal response and HCI reliability of FinFETs are also revealed.