Hot-carrier degradation mechanism under AC stress in MOSFET´s

As device dimensions are scaled down. the hot-carrier(HC) effect is known as one of the most serious constraints to ULSI design. Up to now. hot-carrier degradation by static(DC) stress has been intensively studied. With regard to the degradation by dynamic(AC) stress. only two points have been reported. 1) HC degradation is strongly enhanced by AC stress, particularly when plasma nitride is used as a passivation layer¹⁾²⁾³⁾. 2) For a PSG passivation layer, however, τ AC is simply a linear function of duty ratio R; τ AC = DCR⁴⁾, However, the degradation mechanism under AC stress has not been clarified Physically.