Structural Test Development Overview
Just a few years ago several manufacturers began making optimized structural testers that were more geared to processing Scan and BIST data and operations, as opposed to complex functional sequences. By doing this, the requirements on the ATE were significantly reduced and this in turn reduced the cost associated with the creation of the tester. The market that supports Scan and BIST techniques uses automatic test pattern generation (ATPG) and design-for-test (DFT) techniques to increase the quality metric and to reduce the time-to vectors. The goal here is more about "time-to-market" rather than "test cost."
DFT Case Studies
The Failure Analysis / Correlation Application
Definition - The use of the structural tester by the traditional test organizations - the test, product, and failure analysis engineer. The very small form-factor of the structural tester (desktop) allows the tester to be comfortably located in a cubicle, office, or (kiosk) engineering laboratory.
Purpose - To use the tester in an environment that is linked to a production tester. The structural tester provides a better response time, more flexibility and a lower-cost way to conduct test pattern validation, test program development, and debug-diagnosis or failure analysis that is related to fails on a production tester - commonly called yield-learning during ramp-to-volume.
Key Driver - Time-to-: Optimizations such as reduction of "time-to-market," "time-to-yield," and "time-to volume." The test engineer's goal is to validate vectors and develop the test program more rapidly; or to trace the root causes of systemic failures more quickly.
Focus - The main optimization is the direct link or connection to EDA vector generation (ATPG) software, which is also useful in the design space. The EDA-Link, as it is called, is the ability to create and directly use tool-created vectors without complex and error-prone translations; and for returning fail data directly from the tester's fail log to the diagnostic tools associated with the ATPG tools to rapidly find the gate level element responsible for the fails.
New Directions -- The direct import and export of patterns and vector sets between a desktop or laboratory machine and a production tester. This enables development of vectors in the "easy-access" test environment to be directly applied to the other "difficult production" environment - and for tests associated with failing behavior to easily be transferred from the production machine to the debug machine. Another area of activity is to directly connect and synchronize the desktop-sized structural test machines to e-beam probers and other diagnostic equipments.
Inovys Solutions for Failure Analysis
