RELIABILITY OF POLYSILICON THIN-FILM RESISTORS WITH IRREVERSIBLE RESISTANCE TRANSITION

In this paper, the results of reliability testing (life testing at 125 -degrees-C for 2000 h) and failure analysis of polysilicon thin film r esistors with irreversible resistance transition are presented and dis cussed. The results of the life test show that electrical parameters o f the polysilicon resistors (resistance before transition, transition voltage and resistance after transition) are satisfactorily stable dur ing the life test. Also, calculated values of the mean time before fai lure (MTBF) and the mean time to failure (MTTF) on the basis of the li fe test data confirm that the polysilicon resistors have a satisfactor y level of reliability for long-term applications. Finally, the result s of failure analysis show that typical failure modes of the polysilic on resistors are open, while the responsible failure mechanism is elec tromigration of aluminum during the life test at the contact between t he aluminum line and polysilicon film.