In electron multiplying charge coupled device (EMCCD) image sensors, electron traps in the dielectric stack underneath charge multiplication electrodes may cause undesirable gain ageing. To reduce the gain ageing drift effect, a dielectric stack may be formed that does not include electron traps in regions underneath charge multiplication electrodes. To accomplish this, silicon nitride in the dielectric stack may be removed in regions underneath the charge multiplication electrodes. The EMCCD image sensors can thus be fabricated with a stable charge carrier multiplication gain during their operational lifetime.