International Business Machines Corporation

Timothy J O'Gorman

Kimball M Watson

David Erin Moran

Jeffrey Scott Zimmerman

Steven W Mittl

Mark R Bilak

Joseph M Forbes

Michael D Maurice

Regis D Parent

Curt Guenther

Michael J Maloney

A method for creating a guardband that incorporates statistical models for test environment, system environment, tester-to-system offset and reliability into a model and then processes a final guardband by factoring manufacturing process variation and quality against yield loss.

Statistical guardband methodology

A method and system are provided for determining a guard band voltage differential for testing a microprocessor. The guard band voltage differential approximates microprocessor circuit propagation delay degradation expected to occur over the life of the microprocessor. The system and method are performed by first partitioning a microprocessor into a plurality of cones of n circuit level models. Timing simulation data and degradation data are created to represent, respectively, the timing operation for each of the circuit level model circuit paths, and the hot-electron effects on propagation delay degradation for each of the circuit level models. Propagation delay is identified using this data for each of the circuit paths for the circuit level models at times corresponding to the beginning-of-life and end-of-life of the microprocessor. Propagation delay degradation is calculated as the difference between the propagation delay at these times. A range of applied power supply voltages necessary to successfully perform a functional test of the microprocessor over a corresponding range of microprocessor cycle times is experimentally determined. Based on the calculated propagation delay degradation and on the range of applied power supply voltages, a guard band voltage differential for testing the microprocessor is determined.

Method to calculate hot-electron test voltage differential for assessing

A method of assessing the tolerance of a microprocessor to propagation time degradation caused by electromigration effects and hot electron effects is provided. Reference values for interconnection resistance (IR) degradation and drain current (DC) degradation are compute, at nominal fabrication process and microprocessor lifetime application conditions. These results may be tabulated for a plurality of output driver load capacitances. Test IR degradation and test DC degradation values are calculated by scaling the reference IR and DC degradation values, respectively, for actual test conditions. The circuit propagation time and the propagation delay degradation caused by both electromigration and hot electron effects are calculated at process and lifetime environmental conditions. A timing equation is evaluated using distinctly identified components of the propagation delay degradation caused by electromigration and hot electron effects, to assess the toleration of the microprocessor to electromigration and hot electron induced propagation delay degradation.

Method to assess electromigration and hot electron reliability for

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Williston, VT, United States of America

Timothy J O'Gorman