Low-frequency noise and stress-induced degradation in LDMOS

Statistical charge-based modeling of 1/f noise in standard and high-voltage MOS transistors

“…Despite the fact that until recently, 1/f noise models of standard LV CMOS devices were used to model 1/f noise in HV devices, LDMOS do not follow such models especially under conditions where flicker noise being contributed by drift region becomes significant. This noise source arising from drift region and especially from the extension of gate oxide which overlaps with drift region superficially, was recently experimentally observed [193,194,196]. In more detail, carrier fluctuations due to trapping/detrapping mechanism in the S i /S i O 2 interface occur not only in channel part as was expected but also in the overlap region in drift extension.…”

“…The same conclusions as above can be extracted following a different approach using DC stress measurements [193,194,197]. In the work from this group, the effect of DC stress on flicker noise was examined while a model for flicker noise in LDMOS was proposed [196,198].…”

“…This increase is obtained in the inherent noise of the extended drain, due to degradation in the extended drain region under the gate oxide region. Highvoltage stressing causes an increase in the interface traps, thus increasing 1/f noise due to more intense trapping/detrapping mechanism [193]. The group has demonstrated that the relative percentage of degradation with stressing time in 1/f noise is much higher and occurs much earlier than that for the DC parameters.…”

“…Until nowadays LV 1/f noise models were used to describe 1/f noise at HV-MOSFETs since there was the belief that LV channel part was the only contributor to 1/f noise in these devices. Recent work has shown that this is not the case since the characteristics of 1/f noise in LDMOS are significantly different than standard LV-MOSFETs due to additional noise mechanisms which arise in the extended drain region and more specifically in the extension of gate oxide in the drift region [193,194]. Scope of our work was to develop a new complete compact 1/f noise model for LDMOS transistors for the first time and this task was accomplished [27].…”

“…After this introduction, the fundamental physical procedure that generates 1/f noise in LDMOS is presented [193,194,195] with giving attention to the lack of complete compact models [196,197,198]. After that, the 1/f noise measurement setup as well as the devices under test are presented thoroughly and then we focus on the development of our complete 1/f noise compact model for LDMOSFETs [27] which is charge-based in agreement with EKV3 formulation.…”