Semiconductors

Migrating Industrial DfM into IC Manufacturing 53

calculated based on the actual operating conditions. As a rule of thumb, the

nominal DC lifetime can be multiplied by a factor of 10 to reect time-dependent

bias. But, for many product applications, it is critical to extract the age distribu-

tion of all MOSFETs on a chip and use geometry derating to ensure reliability

of the critical ones.

The oxide failure mechanism related to both high gate voltage and operat-

ing temperature, the negative bias temperature instability (NBTI), mainly

occurs in pMOS devices stressed with negative gate voltage, at 100−250°C

and an oxide electric eld bet