A programmable BIST architecture for clusters of Multiple-Port SRAMs

This paper presents a BIST architecture, based on a single microprogrammable BIST processor and a set of memory wrappers, designed to simplify the test of a system containing many distributed multi-port SRAMs of different sizes (number of bits, number of words), access protocol (asynchronous, synchronous), and timin

Infrastructures and Algorithms for Testable and Dependable Systems-on-a-Chip

Every new node of semiconductor technologies provides further miniaturization and higher performances, increasing the number of advanced functions that electronic products can offer. Silicon area is now so cheap that industries can integrate in a single chip usually referred to as System-on-Chip (SoC), all the components and functions that historically were placed on a hardware board. Although adding such advanced functionality can benefit users, the manufacturing process is becoming finer and denser, making chips more susceptible to defects. Today’s very deep-submicron semiconductor technologies (0.13 micron and below) have reached susceptibility levels that put conventional semiconductor manufacturing at an impasse. Being able to rapidly develop, manufacture, test, diagnose and verify such complex new chips and products is crucial for the continued success of our economy at-large. This trend is expected to continue at least for the next ten years making possible the design and production of 100 million transistor chips. To speed up the research, the National Technology Roadmap for Semiconductors identified in 1997 a number of major hurdles to be overcome. Some of these hurdles are related to test and dependability. Test is one of the most critical tasks in the semiconductor production process where Integrated Circuits (ICs) are tested several times starting from the wafer probing to the end of production test. Test is not only necessary to assure fault free devices but it also plays a key role in analyzing defects in the manufacturing process. This last point has high relevance since increasing time-to-market pressure on semiconductor fabrication often forces foundries to start volume production on a given semiconductor technology node before reaching the defect densities, and hence yield levels, traditionally obtained at that stage. The feedback derived from test is the only way to analyze and isolate many of the defects in today’s processes and to increase process’s yield. With the increasing need of high quality electronic products, at each new physical assembly level, such as board and system assembly, test is used for debugging, diagnosing and repairing the sub-assemblies in their new environment. Similarly, the increasing reliability, availability and serviceability requirements, lead the users of high-end products performing periodic tests in the field throughout the full life cycle. To allow advancements in each one of the above scaling trends, fundamental changes are expected to emerge in different Integrated Circuits (ICs) realization disciplines such as IC design, packaging and silicon process. These changes have a direct impact on test methods, tools and equipment. Conventional test equipment and methodologies will be inadequate to assure high quality levels. On chip specialized block dedicated to test, usually referred to as Infrastructure IP (Intellectual Property), need to be developed and included in the new complex designs to assure that new chips will be adequately tested, diagnosed, measured, debugged and even sometimes repaired. In this thesis, some of the scaling trends in designing new complex SoCs will be analyzed one at a time, observing their implications on test and identifying the key hurdles/challenges to be addressed. The goal of the remaining of the thesis is the presentation of possible solutions. It is not sufficient to address just one of the challenges; all must be met at the same time to fulfill the market requirements

Innovative Techniques for Testing and Diagnosing SoCs

We rely upon the continued functioning of many electronic devices for our everyday welfare, usually embedding integrated circuits that are becoming even cheaper and smaller with improved features. Nowadays, microelectronics can integrate a working computer with CPU, memories, and even GPUs on a single die, namely System-On-Chip (SoC). SoCs are also employed on automotive safety-critical applications, but need to be tested thoroughly to comply with reliability standards, in particular the ISO26262 functional safety for road vehicles. The goal of this PhD. thesis is to improve SoC reliability by proposing innovative techniques for testing and diagnosing its internal modules: CPUs, memories, peripherals, and GPUs. The proposed approaches in the sequence appearing in this thesis are described as follows: 1. Embedded Memory Diagnosis: Memories are dense and complex circuits which are susceptible to design and manufacturing errors. Hence, it is important to understand the fault occurrence in the memory array. In practice, the logical and physical array representation differs due to an optimized design which adds enhancements to the device, namely scrambling. This part proposes an accurate memory diagnosis by showing the efforts of a software tool able to analyze test results, unscramble the memory array, map failing syndromes to cell locations, elaborate cumulative analysis, and elaborate a final fault model hypothesis. Several SRAM memory failing syndromes were analyzed as case studies gathered on an industrial automotive 32-bit SoC developed by STMicroelectronics. The tool displayed defects virtually, and results were confirmed by real photos taken from a microscope. 2. Functional Test Pattern Generation: The key for a successful test is the pattern applied to the device. They can be structural or functional; the former usually benefits from embedded test modules targeting manufacturing errors and is only effective before shipping the component to the client. The latter, on the other hand, can be applied during mission minimally impacting on performance but is penalized due to high generation time. However, functional test patterns may benefit for having different goals in functional mission mode. Part III of this PhD thesis proposes three different functional test pattern generation methods for CPU cores embedded in SoCs, targeting different test purposes, described as follows: a. Functional Stress Patterns: Are suitable for optimizing functional stress during I Operational-life Tests and Burn-in Screening for an optimal device reliability characterization b. Functional Power Hungry Patterns: Are suitable for determining functional peak power for strictly limiting the power of structural patterns during manufacturing tests, thus reducing premature device over-kill while delivering high test coverage c. Software-Based Self-Test Patterns: Combines the potentiality of structural patterns with functional ones, allowing its execution periodically during mission. In addition, an external hardware communicating with a devised SBST was proposed. It helps increasing in 3% the fault coverage by testing critical Hardly Functionally Testable Faults not covered by conventional SBST patterns. An automatic functional test pattern generation exploiting an evolutionary algorithm maximizing metrics related to stress, power, and fault coverage was employed in the above-mentioned approaches to quickly generate the desired patterns. The approaches were evaluated on two industrial cases developed by STMicroelectronics; 8051-based and a 32-bit Power Architecture SoCs. Results show that generation time was reduced upto 75% in comparison to older methodologies while increasing significantly the desired metrics. 3. Fault Injection in GPGPU: Fault injection mechanisms in semiconductor devices are suitable for generating structural patterns, testing and activating mitigation techniques, and validating robust hardware and software applications. GPGPUs are known for fast parallel computation used in high performance computing and advanced driver assistance where reliability is the key point. Moreover, GPGPU manufacturers do not provide design description code due to content secrecy. Therefore, commercial fault injectors using the GPGPU model is unfeasible, making radiation tests the only resource available, but are costly. In the last part of this thesis, we propose a software implemented fault injector able to inject bit-flip in memory elements of a real GPGPU. It exploits a software debugger tool and combines the C-CUDA grammar to wisely determine fault spots and apply bit-flip operations in program variables. The goal is to validate robust parallel algorithms by studying fault propagation or activating redundancy mechanisms they possibly embed. The effectiveness of the tool was evaluated on two robust applications: redundant parallel matrix multiplication and floating point Fast Fourier Transform

What is the Path to Fast Fault Simulation?

Motivated by the recent advances in fast fault simulation techniques for large combinational circuits, a panel discussion has been organized for the 1988 International Test Conference. This paper is a collective account of the position statements offered by the panelists

An effective distributed BIST architecture for RAMs

The present paper proposes a solution to the problem of testing a system containing many distributed memories of different sizes. The proposed solution relies in the development of a BIST architecture characterized by a single BIST processor, implemented as a microprogrammable machine and able to execute different test algorithms, a wrapper for each SRAM including standard memory BIST modules, and an interface block to manage the communications between the SRAM and the BIST processor. Both area overhead and routing costs are minimized, and a scan-based approach allows full diagnostic capabilities of the faults possibly detected in the memories under test

FPGA ARCHITECTURE AND VERIFICATION OF BUILT IN SELF-TEST (BIST) FOR 32-BIT ADDER/SUBTRACTER USING DE0-NANO FPGA AND ANALOG DISCOVERY 2 HARDWARE

The integrated circuit (IC) is an integral part of everyday modern technology, and its application is very attractive to hardware and software design engineers because of its versatility, integration, power consumption, cost, and board area reduction. IC is available in various types such as Field Programming Gate Array (FPGA), Application Specific Integrated Circuit (ASIC), System on Chip (SoC) architecture, Digital Signal Processing (DSP), microcontrollers (μC), and many more. With technology demand focused on faster, low power consumption, efficient IC application, design engineers are facing tremendous challenges in developing and testing integrated circuits that guaranty functionality, high fault coverage, and reliability as the transistor technology is shrinking to the point where manufacturing defects of ICs are affecting yield which associates with the increased cost of the part. The competitive IC market is pressuring manufactures of ICs to develop and market IC in a relatively quick turnaround which in return requires design and verification engineers to develop an integrated self-test structure that would ensure fault-free and the quality product is delivered on the market. 70-80% of IC design is spent on verification and testing to ensure high quality and reliability for the enduser. To test complex and sophisticated IC designs, the verification engineers must produce laborious and costly test fixtures which affect the cost of the part on the competitive market. To avoid increasing the part cost due to yield and test time to the end-user and to keep up with the competitive market many IC design engineers are deviating from complex external test fixture approach and are focusing on integrating Built-in Self-Test (BIST) or Design for Test (DFT) techniques onto IC’s which would reduce time to market but still guarantee high coverage for the product. Understanding the BIST, the architecture, as well as the application of IC, must be understood before developing IC. The architecture of FPGA is elaborated in this paper followed by several BIST techniques and applications of those BIST relative to FPGA, SoC, analog to digital (ADC), or digital to analog converters (DAC) that are integrated on IC. Paper is concluded with verification of BIST for the 32-bit adder/subtracter designed in Quartus II software using the Analog Discovery 2 module as stimulus and DE0-NANO FPGA board for verification

On-Line Dependability Enhancement of Multiprocessor SoCs by Resource Management

This paper describes a new approach towards dependable design of homogeneous multi-processor SoCs in an example satellite-navigation application. First, the NoC dependability is functionally verified via embedded software. Then the Xentium processor tiles are periodically verified via on-line self-testing techniques, by using a new IIP Dependability Manager. Based on the Dependability Manager results, faulty tiles are electronically excluded and replaced by fault-free spare tiles via on-line resource management. This integrated approach enables fast electronic fault detection/diagnosis and repair, and hence a high system availability. The dependability application runs in parallel with the actual application, resulting in a very dependable system. All parts have been verified by simulation