Research

Our research efforts pay special attention to topics related to test, reliability and fault tolerance of digital systems as well as innovative architectures for approximative and heterogeneous computing. A part of our work is done in cooperation with various partners coming both from national and international universities and from industry.

CA - Current Research Projects

An important problem in modern technology nodes in nano-electronics are early life failures, which often cause recalls of shipped products and incur high costs. An important root cause of such failures are marginal circuit structures, which pass a conventional manufacturing test, but are not able to cope with the later workload and stress in the field. Such structures can be identified on the basis of non-functional indicators, in particular by testing the timing behavior. For an effective and cost-efficient test of these indicators, the FAST project investigates novel scan designs and built-in self-test strategies for circuits, which can operate at frequencies beyond the functional specification to detect small deviations of the nominal timing behavior and thus potential early life failures.

since 02.2017, DFG-Project: WU 245/19-1

The project in detail:

State-of-the-art nanoscale technologies allow for the integration of billions of transistors with feature sizes of 14 nm or below into a single chip. This enables innovative approaches and solutions in many application domains, but it also comes along with fundamental challenges. Early life failures are particularly critical, as they can cause product recalls associated with a loss of billions of dollars. A major cause of early life failures are "weak" devices that operate correctly during manufacturing test, but cannot stand operational stress in the field. While other failure mechanisms, such as aging or external disturbances, to some extent, may be compensated by a robust design, potential early life failures must be detected by tests, and the respective systems have to be sorted out. This requires specific approaches far beyond today’s state-of-the-art.

As they work properly in the beginning, weak structures must be identified by analyzing the non-functional circuit behavior with the help of appropriate observables. Besides power consumption, the circuit timing is one of the most important reliability indicators. In particular, small delay faults may indicate marginal hardware that can degrade further under stress. However, they can be “hidden” at nominal frequency and only be detected at higher frequencies (“faster-than-at-speed test” / FAST). Therefore, conventional approaches for testing reach their limitations, and new methods must be investigated and developed in the following three domains:

  1. Specific techniques for „design for test“ (DFT) must be developed to deal with the challenges of testing beyond nominal frequency.
  2. Strategies for test scheduling must ensure that a maximum fault coverage is achieved with a minimum number of test frequencies and a short test time.
  3. Appropriate metrics are needed to quantify the coverage of weak devices. Here it is particularly challenging to distinguish the behavior of week devices from variations due to nanoscale integration.

Since FAST imposes extreme requirements on the automatic test equipment (ATE), it is very important to support an efficient implementation as a built-in self-test (BIST).

Within the framework of the project, strategies and solutions will be developed for the problems mentioned above. This way, the enormous cost of a traditional „burn-in“ test can be reduced, thus enabling the introduction of nanoscale technology to new application domains.

In the project „SHIVA: Secure Hardware for Information Processing“, coordinated by Prof. Dr. Wunderlich (Institut für Technische Informatik), novel design and verification methods are researched and developed to increase and assure the security of microelectronic hardware, used for instance in automobile, medical, or industrial applications. These methods will help to achieve increasing security requirements and prevent system manipulation, extraction of critical data or process information, and IP theft.

More information on our german website.

since 02.2016, Forschungsprogramm der Baden-Württemberg Stiftung
IKT-Sicherheit für weltweit vernetzte vertrauenswürdige Infrastrukturen

 

SEE GERMAN PAGES

VLSI designs incorporate specialized instrumentation for post-silicon validation and debug, volume test and diagnosis, as well as in-field system maintenance. Due to the increasing complexity, however, the embedded infrastructure and flexible access mechanisms such as Reconfigurable Scan Networks (RSNs) themselves become a dependability bottleneck.

While efficient verification, test, and diagnosis techniques exist for combinational and some classes of sequential circuits, Reconfigurable Scan Networks (RSNs) still pose a serious challenge. RSNs are controlled via a serial interface and exhibit deeply sequential behavior (cf. IJTAG, IEEE P1687). Due to complex combinational and sequential dependencies, RSNs are beyond the capabilities of existing algorithms for verification, test, and diagnosis which were developed for classical, non-reconfigurable scan networks. The goal of ACCESS is to establish a methodology for efficient verification, test and diagnosis of RSNs to meet stringent reliability, safety and security goals.

seit 08.2014, DFG-Projekt: WU 245/17-1

The project in detail:

VLSI designs incorporate specialized instrumentation for post-silicon validation and debug, volume test and diagnosis, as well as in-field system maintenance. Examples of instruments for efficient localization of silicon defects and design bugs include trace buffers, performance monitors, event counters, or scan chains. Test instrumentation includes test controllers, test wrappers, scan chains and structures for pattern decompression and compaction. Such instruments are used both in manufacturing test and for in-field test. Maintenance instrumentation is mainly used in regular system operation for monitoring, error detection, and reliability management. It includes, for instance, error monitors, memory repair controllers, and structures for system reprogramming and reconfiguration. Instruments for manufacturability, e.g. process monitors, facilitate the monitoring of chip performance and reliability. Due to the increasing complexity, however, the embedded infrastructure and access mechanisms themselves become a dependability bottleneck.

While efficient verification, test, and diagnosis techniques exist for combinational and some classes of sequential circuits, Reconfigurable Scan Networks (RSNs) still pose a serious challenge. RSNs are controlled via a serial interface and exhibit deeply sequential behavior (cf. IJTAG, IEEE Std 1687). Due to complex combinational and sequential dependencies, RSNs are beyond the capabilities of existing algorithms for verification, test, and diagnosis which were developed for classical, non-reconfigurable scan networks. The goal of ACCESS is to establish a methodology for efficient verification, test and diagnosis of RSNs to meet stringent reliability, safety and security goals. This comprises:

  • Unified RSN Modeling
  • Verification of Model Consistency
  • Formal Verification to guarantee operability, safety, and security
  • Efficient Test Generation and Fault Simulation
  • Post-Manufacture and In-Field Test
  • Diagnosis of Scan Infrastructure Faults
  • Robust Access to Faulty Scan Infrastructure

This work is supported by the German Research Foundation (DFG) under grant WU 245/17-1 (2014-2017).

Hans-Joachim Wunderlich (i.R.)
Prof. Dr. rer. nat. habil.

Hans-Joachim Wunderlich (i.R.)

Heading the Research Group Computer Architecture

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