Mechanical stress and hydrogen effects on hot carrier injection

Short-channel length n-MOSFETs encapsulated by various passivation layers have been investigated from viewpoint of mechanical stress and hydrogen effects on hot-carrier injection. Device lifetime is strongly afected by passivation structure, thickness and composition. As the thickness decreases or the composition approaches to SiO structure, the device lifetime is remarkably improved It is found that the device lifetime is degraded by additive effects obtained by combining the hydrogen effect with the mechanical stress effect. We electrically stressed the encapsulated devices under mechanically induced compressive stress, and examined the device degradations. The p-SiN encapsulated devices subjected to uniaxial compresive stress of 2×10⁹dyne/cm²are degraded more rapidly by a factor of 3 to 5 compared to the devices without stress.