Testability enhancement of a basic set of CMOS cells

Testing should be evaluated as the ability of the test patterns to cover realistic faults, and high quality IC products demand high quality testing. We use a test strategy based on physical design for testability (to discover both open and short faults, which are difficult or even impossible to detect). Consequentially, layout level design for testability (LLDFT) rules have been developed, which prevent the faults, or at least reduce the chance of their appearing. The main purpose of this work is to apply a practical set of LLDFT rules to the library cells designed by the Centre Nacional de Microelectrònica (CNM) and obtain a highly testable cell library. The main results of the application of the LLDFT rules (area overheads and performance degradation) are summarized and the results are significant since IC design is highly repetitive; a small effort to improve cell layout can bring about great improvement in design

Layout level design for testability strategy applied to a CMOS cell library

The layout level design for testability (LLDFT) rules used here allow to avoid some hard to detect faults or even undetectable faults on a cell library by modifying the cell layout without changing their behavior and achieving a good level of reliability. These rules avoid some open faults or reduce their appearance probability. The main purpose has been to apply that set of LLDFT rules on the cells of the library designed at the Centre Nacional de Microelectronica (CNM) in order to obtain a highly testable cell library. The authors summarize the main results (area overhead and performance degradation) of the application of the LLDFT rules on the cell

Interconnect yield analysis and fault tolerance for field programmable gate arrays

Imperial Users onl

Cost modelling and concurrent engineering for testable design

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.As integrated circuits and printed circuit boards increase in complexity, testing becomes a major cost factor of the design and production of the complex devices. Testability has to be considered during the design of complex electronic systems, and automatic test systems have to be used in order to facilitate the test. This fact is now widely accepted in industry. Both design for testability and the usage of automatic test systems aim at reducing the cost of production testing or, sometimes, making it possible at all. Many design for testability methods and test systems are available which can be configured into a production test strategy, in order to achieve high quality of the final product. The designer has to select from the various options for creating a test strategy, by maximising the quality and minimising the total cost for the electronic system. This thesis presents a methodology for test strategy generation which is based on consideration of the economics during the life cycle of the electronic system. This methodology is a concurrent engineering approach which takes into account all effects of a test strategy on the electronic system during its life cycle by evaluating its related cost. This objective methodology is used in an original test strategy planning advisory system, which allows for test strategy planning for VLSI circuits as well as for digital electronic systems. The cost models which are used for evaluating the economics of test strategies are described in detail and the test strategy planning system is presented. A methodology for making decisions which are based on estimated costing data is presented. Results of using the cost models and the test strategy planning system for evaluating the economics of test strategies for selected industrial designs are presented

Efficient Built In Self Repair Strategy for Embedded SRAM with selecteble redundancy

Built-in self -test (BIST) refers to those testing techniques where additional hardware is added to a design so that testing is accomplished without the aid of external hardware. Usually, a pseudo-random generator is used to apply test vectors to the circuit under test and a data compactor is used to produce a signature. To increase the reliability and yield of embedded memories, many redundancy mechanisms have been proposed. All the redundancy mechanisms bring penalty of area and complexity to embedded memories design. Considered that compiler is used to configure SRAM for different needs, the BISR had better bring no change to other modules in SRAM. To solve the problem, a new redundancy scheme is proposed in this paper. Some normal words in embedded memories can be selected as redundancy instead of adding spare words, spare rows, spare columns or spare blocks. Built-In Self-Repair (BISR) with Redundancy is an effective yield-enhancement strategy for embedded memories. This paper proposes an efficient BISR strategy which consists of a Built-In Self-Test (BIST) module, a Built-In Address-Analysis (BIAA) module and a Multiplexer (MUX) module. The BISR is designed flexible that it can provide four operation modes to SRAM users. Each fault address can be saved only once is the feature of the proposed BISR strategy. In BIAA module, fault addresses and redundant ones form a one- to- one mapping to achieve a high repair speed. Besides, instead of adding spare words, rows, columns or blocks in the SRAMs, users can select normal words as redundancy

Testing a CMOS operational amplifier circuit using a combination of oscillation and IDDQ test methods

This work presents a case study, which attempts to improve the fault diagnosis and testability of the oscillation testing methodology applied to a typical two-stage CMOS operational amplifier. The proposed test method takes the advantage of good fault coverage through the use of a simple oscillation based test technique, which needs no test signal generation and combines it with quiescent supply current (IDDQ) testing to provide a fault confirmation. A built in current sensor (BICS), which introduces insignificant performance degradation of the circuit-under-test (CUT), has been utilized to monitor the power supply quiescent current changes in the CUT. The testability has also been enhanced in the testing procedure using a simple fault-injection technique. The approach is attractive for its simplicity, robustness and capability of built-in-self test (BIST) implementation. It can also be generalized to the oscillation based test structures of other CMOS analog and mixed-signal integrated circuits. The practical results and simulations confirm the functionality of the proposed test method

Course development in IC manufacturing

A traditional curriculum in electrical engineering separates semiconductor processing courses from courses in circuit design. As a result, manufacturing topics involving yield management and the study of random process variations impacting circuit behaviour are usually vaguely treated. The subject matter of this paper is to report a course developed at Texas A&M University, USA, to compensate for the aforementioned shortcoming. This course attempts to link technological process and circuit design domains by emphasizing aspects such as process disturbance modeling, yield modeling, and defect-induced fault modeling. In a rapidly changing environment where high-end technologies are evolving towards submicron features and towards high transistor integration, these aspects are key factors to design for manufacturability. The paper presents the course's syllabus, a description of its main topics, and results on selected project assignments carried out during a normal academic semeste