The hot carrier (HC) reliability has been investigated in MOSFETs with ultra-thin SiO 2 gate-oxide ranging from T ox=3.5 to 1.2 nm and in high speed CMOS technologies in order to identify the worst-case of HC injections. Distinctions are obtained between the influence of the T ox thinning and the shrink of the gate-length with L G ranging from 0.25 to 0.1 μm. Results show that the worst-case of HC damage can be different from the bias condition of the maximum substrate current (IB) in N-channel devices and of the hot electron (HE) injections in P-channel devices with the T ox and L G margin. It is shown that the interface trap generation (Δ N it) has become the main damage mechanism at long term with the use of the correlation between charge pumping analysis and drain current reduction. We focus on the hole injection efficiency, the extension of the degraded region (Δ L) with the L G reduction and the influence of the carrier energy which all participate to the degradation of ultra-thin gate-oxide MOSFETs submitted to carrier injections.