Hot carrier effects in sub-micron lightly doped drain (LDD) n-channel
MOSFETs under static (DC) stress are studied in order to establish the degradation
mechanisms of such devices. Degradation is monitored as a function of time at various
gate voltages. Under accelerated aging conditions (i.e. large drain voltages) the gate
voltage for maximum degradation is found to be different than the gate voltage for
which the substrate current is maximum; this is in contrast to the results of previous
workers who found degradation and substrate current to be strongly correlated.
However, under normal operating conditions, degradation and substrate current are
found to be correlated. Furthermore, through the use of charge pumping
measurements it is shown that two primary mechanisms are accountable for the
degradation of these devices at small and large gate voltages. First, at large gate
voltages there is an increase in the degradation which is predominantly due to electron
injection and trapping in the oxide. An alternating static injection experiment shows
that this type of electron trapping degradation is recoverable. Second, at small gate
voltages degradation is mainly related to interface state generation near the drain LDD
region. Floating gate measurements demonstrate that electron and hole injection occurs
at large and small gate voltages, respectively. It is also shown that maximum interface
state creation occurs when electron and hole injection happens simultaneously. / Graduation date: 1994
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/36173 |
| Date | 18 June 1993 |
| Creators | Aminzadeh, Payman G. |
| Contributors | Wager, John F. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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