| Summary: | 碩士 === 國立成功大學 === 微電子工程研究所碩博士班 === 97 === In this thesis, device characteristics and hot carrier reliability of n-type LDMOS transistors with different device dimension are investigated. The device used in this thesis has four main layout parameters: channel length, accumulation length, length of drift region with gate control and length of drift region without gate control.
As for device characteristics, the effect of parameters of channel length and accumulation length are more significant than that of parameters of drift region with gate control and length of drift region without gate control. The unexpected connection between Ron, BVoff and accumulation length can be explained by TCAD Simulation. Then we choose a standard device dimension to perform constant voltage hot carrier stress and discuss the hot carrier degradation phenomenon and mechanism. The degradation of Ron reveals different power index of degradation for different stressed bias. By means of TCAD simulation and charge pumping analysis, the phenomenon of anomalous degradation can be discussed and explained in detail.
Besides, effects of device dimension on Ron lifetime are investigated. Among prodigious enhancement of lifetime is certain as accumulation length increased. So, accumulation length is reduced and the effect of this change on Ron and Idsat are discussed. Charge pumping analysis and TCAD simulation are used to evidence for the stress experimental results.
Finally, compare with device characteristics and hot carrier stressed experiments. We can conclude that accumulation length is an important concern in this device when considering both device performance and hot carrier reliability. Such an analysis can provide useful feedback in designing LDMOS devices.
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