Apparatus, and computer program product for implementing deterministic based broken scan chain diagnostics

Apparatus for implementing deterministic based broken scan chain diagnostics in a computer test system connected to a Physical Failure Analysis system comprising:

• a set of deterministic test patterns;
• said set of deterministic test patterns being generated using a base deterministic test pattern set generated by an Automatic Test Pattern Generation (ATPG) system in a computer test system;
• each of the deterministic test pattern being a predetermined Level Sensitive Scan Design (LSSD) pattern;
• a test control program utilizing all potential system functional paths and all system clocks on a device under test, loading a deterministic test pattern into each scan chain in the device under test in a system mode using lateral insertion of respective deterministic values of the deterministic test pattern into each of a plurality of latches of each said scan chain via system data ports and applying system clocks to capture the respective deterministic values in each of the plurality of latches of each said scan chain;
• unloading each scan chain and identifying a last switching latch in each scan chain;
• repeating the generating, loading, unloading and identifying a last switching latch in each said scan chain testing steps a selected number of times with the deterministic test pattern;
• and checking for consistent results of the identified last switching latch in each scan chain and responsive to consistent results being identified, sending the identified last switching latch in each scan chain to said Physical Failure Analysis system to localize a physical defect;
• and responsive to consistent results not being identified, selecting another deterministic test pattern.

A computer program product for implementing deterministic based broken scan chain diagnostics of a device under test in a computer test system connected to a Physical Failure Analysis system, said computer program product including instructions stored on a computer recording medium consisting one of a floppy disk, an optically read compact disk, a compact disk read only memory (CD-ROM), and a tape, wherein said instructions, when executed by the computer test system to cause the computer system to perform the steps of:

• generating a deterministic test pattern using a base deterministic test pattern set generated by an Automatic Test Pattern Generation (ATPG) system;
• the deterministic test pattern being a predetermined Level Sensitive Scan Design (LSSD) pattern;
• utilizing all potential system functional paths and all system clocks on a device under test, loading the deterministic test pattern into each scan chain in the device under test in a system mode using lateral insertion of respective deterministic values of the deterministic test pattern into each of a plurality of latches of each said scan chain via system data ports and applying system clocks to capture the respective deterministic values in each of the plurality of latches of each said scan chain;
• unloading each scan chain and identifying a last switching latch in each scan chain;
• repeating the generating, loading, unloading and identifying a last switching latch in each said scan chain testing steps a selected number of times with the deterministic test pattern;
• checking for consistent results of the identified last switching latch in each scan chain;
• and responsive to consistent results being identified with the deterministic test pattern, sending the identified last switching latch in each scan chain to said Physical Failure Analysis system to localize a physical defect;
• and
• responsive to consistent results not being identified, selecting another deterministic test pattern.