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Channel hot
electron (CHE) injection
occurs when
both the gate voltage and the drain voltage are significantly higher
than the source voltage, with VG≈VD. Channel carriers that travel
from the source to the drain are sometimes driven towards the gate oxide
even before they reach the drain because of the high gate voltage.
Figure 2.
CHE injection involves propelling of carriers in the
channel
toward the oxide even before they reach the drain area;
source: Hitachi Semiconductor Reliability Handbook
Substrate hot
electron (SHE) injection
occurs when
the substrate back bias is very positive or very negative, i.e.,
|VB|>>
0. Under this condition, carriers of one type in the substrate are
driven by the substrate field toward the Si-SiO2 interface. As they move
toward the substrate-oxide interface, they further gain kinetic energy
from the high field in surface depletion region. They eventually
overcome the surface energy barrier and get injected into the gate
oxide, where some of them are trapped.
Figure 3.
SHE injection involves trapping of carriers from the
substrate;
source: Hitachi Semiconductor Reliability Handbook
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See
Also:
Die Failures; Failure Analysis; Reliability Models
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