Studies Of The LDD Process For HCE Improvement

Hot carriers refer to the carriers that have gained high kinetic energy after being accelerated by a strong electric field in areas of high field or by impact ionization. Hot carriers possibly will inject into the gate oxide to generate interface states. And the charge trapping of this interface states should be the root cause of device degradation. The hot carrier effect has become more severe as the device size continues to scale down to submicron range. This aging phenomenon that threatens the circuit and product lifetimes warrants it to be considered as the key challenge in reliability. The most widely used device structure for improving the hot carrier reliability is the lightly doped drain (LDD). Studies on LDD engineering have been carried out for deep submicron technology to enhance device hot carrier immunity. The result shows 10 times improvement in hot carrier injection (HCI) DC lifetime from LDD implant optimization. This substantial improvement is attributed to the mechanisms of reduction and departure of high electrical field from the drain area.