Fully X-tolerant, very high scan compression scan test systems and techniques

US7979763B2 · kind B2 · utility

Assignee

• SYNOPSYS, INC. · US

Inventors

• Peter Wohl · Williston, US
• John A. Waicukauski · Tualatin, US
• Frederic J. Neuveux · Meylan, FR

Key dates

• Filing date: Jan 30, 2009
• Grant date: Jul 12, 2011
• Expiry date: Sep 20, 2029

Classification

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

Abstract

Scan testing and scan compression are key to realizing cost reduction and shipped quality. New defect types in ever more complex designs require increased compression. However, increased density of unknown (X) values reduces effective compression. A scan compression method can achieve very high compression and full coverage for any density of unknown values. The described techniques can be fully integrated in the design-for-test (DFT) and automatic test pattern generation (ATPG) flows. Results from using these techniques on industrial designs demonstrate consistent and predictable advantages over other methods.