Hydrogen desorption and diffusion in PECVD silicon nitride. Application to passivation of CMOS active pixel sensors

Presented either as a source or as a barrier to hydrogen, plasma deposited silicon nitride can impact microelectronic device performances. The objective of this paper is to clarify the hydrogen behavior in silicon nitride in order to optimize film characteristics for each microelectronic application. A design of experiments methodology was used to statistically discriminate films properties which govern hydrogen diffusion and desorption from PECVD silicon nitride. Finally, we confirm, thanks to trials on CMOS active pixel sensor devices and dark current measurements, the role of the SiN passivation layer on Si remaining defect and we propose an optimized passivation stack.