Scan chain fail diagnostics

US8006152B2 · kind B2 · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Samuel I. Ward · Austin, US
• Patrick R. Crosby · Austin, US
• William Ramsour · Pflugerville, US
• Bao G. Truong · Austin, US

Key dates

• Filing date: Jan 12, 2009
• Grant date: Aug 23, 2011
• Expiry date: Aug 15, 2029

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R31/318547
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A method comprises generating a test pattern for a device under test (DUT), wherein the DUT comprises a plurality of scan chains coupled to a plurality of multiple input shift registers (MISRs). The plurality of faults detected by a first MISR and by a second MISR are identified. In the event the plurality of faults detected by the first MISR does not include any of the plurality of faults detected by the second MISR and the plurality of faults detected by the second MISR does not include any of the plurality of faults detected by the first MISR, the first MISR and the second MISR are coupled as an independent MISR pair. The test pattern is applied to the DUT to generate a scan chain output. The independent MISR pair captures the scan chain output to generate a test signature. The test signature is compared with a known good signature.