With rapid development in semiconductor technology, today's large and complex integrated circuits require a large amount of test data to achieve desired test coverage. Test cost, which is proportional to the size of the test set, can be reduced by generating a small number of highly effective test patterns. Automatic Test Pattern Generators (ATPGs) generate effective deterministic test patterns for different fault models and can achieve high test coverage. To reduce ATPG-produced test set size, design for test (DFT) methods can be used to further improve the ATPG process and apply generated test patterns in more efficient ways.
The first part of this dissertation introduces a test point insertion (TPI) technique that reduces the test pattern counts and test data volume of a design by adding additional hardware called control points. These dedicated control points are inserted at internal nodes of the design to resolve large internal conflicts during ATPG. Therefore, more faults can be detected by a single test pattern. To minimize silicon area needed to implement these control points, we propose a method that reuses some existing functional flip-flops as drivers of the control points, instead of inserting dedicated flip-flops for the control points. Experimental results on industrial designs indicate that the proposed technique can achieve significant test pattern reductions, similar to the control points using dedicated flip-flops.
The second part of this dissertation proposes a staggered ATPG scheme that produces deterministic test-per-clock-based staggered test patterns by using dedicated compactor scan chains to capture additional test responses during scan shift cycles that are used for regular scan cells to completely load each test pattern. These compactor scan chains are formed by dedicated capture-per-cycle observation test points inserted at suitable locations of the design. By leveraging this new scan infrastructure, more compacted test patterns can be generated, and more faults can also be systematically detected during the simulation process, thus reducing the overall test pattern count.
To meet the stringent test requirements for in-system test (especially for automotive test), a built-in self-test (BIST) approach, called Stellar BIST, is introduced in the last part of this dissertation. Stellar BIST employs a dedicated BIST infrastructure with additional on-system memory to store some parent test patterns (seeds). Derivative test patterns can be obtained by complementing selected bits of corresponding parent patterns through an on-chip Stellar BIST controller. A dedicated ATPG process is also proposed for generating a minimal set of test patterns that need to be stored and their effective derivative patterns that require short test application time. Furthermore, the proposed scheme can provide flexible trade-offs between stored test data volume and test application time.