Effect of Hydrogen Molecule Release on NBTI by Low-Temperature Pre-Treatment in P-Channel Power VDMOS Transistors

Hydrogen molecules in the SiO2 layer and the Si-SiO2 interface play a key role in the reliability of Si-based devices by affecting the formation of defects. This paper focuses on the effect of hydrogen molecule release on the negative bias temperature instability (NBTI) by low-temperature pre-treatment (LTPT) in p-channel power vertical-double-diffused metal-oxide-semiconductor field-effect transistor (VDMOSFET). The negative bias temperature stress (NBTS) and LTPT are observed to be able to shift the threshold voltage. The number of defects is separated by the subthreshold midgap technique (SMGT). The evolution of atoms at low temperature and the formation of defects during NBTS are verified through simulation and theoretical analysis, respectively. Additionally, it is also validated by a hydrogen-soaking pre-treatment (HSPT) experiment. The LTPT makes it easier for reactive hydrogen atoms to form hydrogen molecules. This process can promote the conversion of oxide charges to interface traps during NBTS and may even exacerbate the instability. Furthermore, although LTPT has been proven to improve device performance, it is not effective in mitigating instability during NBTS. Overall, this discovery points to a superior method of reducing NBTI by decreasing hydrogen-related impurities during the manufacturing and packaging processes of p-channel power VDMOS transistors.