Advanced Adaptive Test
Overview
Until OptimalTest combined adaptive testing techniques with …
- Modern database technology
- Real-time software tools
- Seamless networking
… many viewed adaptive testing only as a way to reduce test time. But with OptimalTest's comprehensive, innovative test management solutions, adaptive testing also:
- Significantly improves yield learning, yield reclamation, reliability and quality
- Achieves these improvements in real time so that data becomes immediately actionable so products and operations can evolve
- Processes more data with more automation and higher data integrity while enhancing its value as useful, accessible information
Modern testing has progressed beyond separating good chips from bad. The multiple disciplines of design, fab, test, quality and reliability all put unique demands on the effectiveness of the test program. In the past, these demands were prohibited by cost and the lack of real-time data to differentiate one chip from another. Therefore, traditional testing applied the same, compromised test program to all chips. However OptimalTest’s application of adaptive testing encompasses enterprise-wide networks, modern databases and the advantages of real-time results -- as well as two innovative methodologies for establishing reference dies and flexible rules – to unleash the power of leveraging data across the enterprise.
OptimalTest’s advanced integrated infrastructure and centralized database management gives you the ability to capture data anywhere in the design-fab-test process, as well as anywhere globally, and to overlay and mine it for its value content to drive adaptive testing.
Benefits
OptimalEnterprise – A Platform for Advanced Adaptive Test [read more]
OptimalEnterprise, its database, OT-Portal and OT-Rules together provide a complete platform for created, deploying, managing and monitoring the performance of Advanced Adaptive rules. This process includes:
- Analysis of data
- Creation and modification of rules
- Automatic publication of adaptive test rules from design centers to test floors (even in disconnected scenarios such as fabless / subcon)
- Rule execution
- Email alert generation
- Collection of detailed rule performance data for analysis OptimalEnterprise is the ONLY solution to cover the entire process from design through execution and to reporting and analysis. It is also the ONLY solution specifically designed to support global operations.
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Adaptive TTR
OptimalTest’s patented adaptive Test Time Reduction (TTR) methodology lets you reduce the number of tests being performed on each part or dice without losing control of quality.
The TTR analysis and simulation tools provide test engineers with detailed information about the performance of each test in the test program over hundreds of thousands of parts. Using this data, the simulator guides the user through the process of determining which tests can be safely removed and the potential resulting impact on DPM (Defects per Million). Often, tests can be flagged for removal without impacting DPM because historically they never fail.
The beauty of performing adaptive TTR is that the tests are not physically removed from the test program. Instead, OT-Proxy enables or disables the tests during testing depending on the health of the material and equipment. For the first parts, dice or wafers under test, OT-Proxy will leave the tests enabled and gather sampling data to ensure that the tests are behaving normally. Additionally, the user can specify that once TTR has started, every few dice or parts the tests are sampled again.
Reference Dice [read more]
Adaptive TTR is also geographically aware – it takes into account the current probing location on a wafer so edge dice can be tested more intensively than the rest of the wafer and it uses reference dice to further validate the quality of a wafer before testing.
Reference dice on a wafer were tested first before regular probing started When the patented reference dice methodology is selected, probing starts with a number of touchdowns strategically located in different places around the wafer. In these touchdowns, all tests are executed and TTR is not performed. Instead, the results are used to verify process stability before probing continues on the rest of the wafer.
Quality Augmentation [read more]
Using the TTR engine it is also possible to perform quality augmentation by adding tests. With this technique, long-running tests that have a significant impact on test time can be run in sampling mode while the rest of the test program runs for the entire wafer or lot. Combining this with reference dice provides you with even higher quality.
See the presentation Advanced Adaptive Testing for more information on reference dice and quality augmentation techniques.
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Outlier Detection
OptimalEnterprise constitutes a platform for higher quality testing. One family of algorithms implemented by the platform is specifically designed to “kill” marginal dice that received a passing bin during wafer test.
Outlier detection is integrated into the wafer test process. Once testing is complete, the algorithm is run and a new inkless wafer map is issued for the tested wafers with the corrected bin results.
