Hot-carrier injection phenomena in submicron dimension NMOS transistors are studied by directly measuring gate current as low as 1×10-15 A. Experimental results show that two new types of injection, avalanche induced hot-hole (AHH) and hot-electron (AHE) injection, and secondary ionization induced substrate hot-electron (SIHE) injection occur in further scaled down devices with conventional structure.
Both injections, in addition to already reported “Channel Hot-Electron Injection”, cause long term degradation in device characteristics. Serious degradation of transconductance is induced by AHH injection. SIHE injection also induce significant threshold voltage shift, even when VDs<3 V. Thus, these injection phenomena can be stringent constraints for the design of a submicron NMOS transistor.