Effect of High Temperature on Recovery of Hot Carrier Degradation of scaled nMOSFETs in DRAM

Abstract

Recovery mechanism of hot carrier degradation of nMOSFETs in DRAM under a high temperature environment was investigated. Hot carrier injection was tested under the high temperature (125°C), and the devices were stored under the room temperature to high temperature environment (25°C~280°C). The device stored under the room temperature showed non-recoverable damages. On the other hand, the device stored under high temperature over 120°C showed recovery characteristics for 64~70% of Idsat, 71% of Vth. To confirm a fast recovery effect, the fast (1μs) measurement method was used, and it confirmed that there was no fast recovery. In addition, the hot carrier stress was applied after confirming recovery characteristics, and it showed same degradation percentile change as before the recovery test. These results indicate that hot carrier lifetime estimation should be carefully evaluated by concerning not only temperature effect but also recovery effect.