System and method for measuring circuit performance degradation due to PFET negative bias temperature instability (NBTI)
AssigneeInternational Business Machines Corporation
InventorsWagdi William Abadeer, Wayne Frederick Ellis, Patrick R. Hansen, Jonathan M. McKenna
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Abstract
A ring oscillator (and test circuit incorporating the ring oscillator and test method therefor) includes an odd number of elements interconnected in a serially-connected infinite loop, each oscillator element having an associated programmable delay feature. The circuit can be used to measure effects of Negative Bias Temperature Instability (NBTI) in p-channel MOSFETs (PFETs).
Claims20
A ring oscillator comprising an odd number of elements interconnected in a serially-connected infinite loop, each said element having an associated delay unit, each said delay unit having a programmable delay.
A test circuit to measure a Negative Bias Temperature Instability (NBTI) effect for PFETs (p-channel MOSFET) by stressing a target PFET component with at least one stress condition, said target PFET component being integrated as a component into said test circuit, said target PFET component having a source, a drain, and a gate, said test circuit comprising:
- a ring oscillator comprising an odd number of oscillator elements interconnected serially in an infinite loop, wherein at least one said target PFET component is integrated into said ring oscillator, said target PFET being integrated into said ring oscillator in such configuration that hot carrier effects from other components in said test circuit do not affect said NBTI effect;
- and
- a test output providing a point to measure at least one parameter of said ring oscillator.
A method of testing a PFET (p-channel field effect transistor), comprising:
- incorporating a target PFET into a ring oscillator having an odd number of elements;
- performing at least one stress test on said PFET;
- and
- measuring at least one characteristic of said ring oscillator based on independently controlling both a frequency parameter and a duty factor parameter of said ring oscillator.
Dependencies are inferred from the claim text.