ST Microelectronics

Motivation:

Development of a Cost Effective Deep sub-micron (DSM) Test Strategy based on an optimal use of Scan, Functional and fast IDDQ tests

Project Objectives:

• Evaluate DSM IDDQ application within production test constraints
• Evaluate IDDQ test effectiveness
• Selection of an optimal IDDQ test strategy
• Compare IDDQ test strategy effectiveness
• Constraints:
  • Ease of application in a production test environment

Module and Test platform

• QD-1010 Advanced IDDQ measurement module.
• Teradyne Catalyst

Test Vehicles:

• Audio Product
  • 0.18µm CMOS – 395 K gates
  • Estimated max leakage: 80µA
  • Typical leakage < 10µA
  • 100 IDDQ strobes/die – 95.3% IDDQ Fault coverage
• Technology Test Chip
  • 0.35µm CMOS – 500K gates – 16Kx16 SRAM – BIST – Logic
  • Estimated Core leakage: < 1µA
  • 123 IDDQ strobes/die – 96% IDDQ Fault coverage

Measurement Module Validation Results:

• ATE (Catalyst) measurement resource specs:
  • matrix source – 2mA range, 14 bit
    • Nominal resolution: 250nA
  • Accuracy: + (0.1% measure + 1uA)
• QD-1010 module measurement specs:
  • multiple threshold programmable module
  • 1mA range, 16 bit – 4 samples,
    • better than 90nA measurement repeatability

To compare the two measurement instruments an experiment was run whereby measurements were taken on multiple vectors with both the ATE and the QD-1010. Each measurement was repeated 100 times
The graphs shows the standard deviation of the measurements for each vector. The IDDq_STOP measurements are the ATE measurements, the IDDq_FAST measurements are the QD-1010 measurements.

Results:>

The QD-1010, with a typical measurement time of 100µs per measurement, offers also a 10 times better measurement repeatability and resolution compared to the ATE, resulting in a considerable test time reduction, thereby reducing test costs and supporting product quality improvement at no extra cost.

A return of investment (ROI) was observed after testing 60K devices.

Conclusion:

ST-Microelectronics experienced significant test time reductions, leading to considerable cost savings combined with a short ROI when making use of Q-Star Tests high quality and high speed loadboard solutions.
The use of a loadboard measurement modules enables further test optimization and the QD-1010 measurement resolution and the on-board data processing capabilities support DSM IDDQ test strategies, making the module a standard part of the test setup.

References:

• Fudoli A., Ascagni A., Appello D., Manhaeve H. , A Practical Evaluation of IDDQ Test Strategies for Deep Submicron Production Test Application. Experiences and Targets from the Field. Proceedings of the 8th IEEE European Test Workshop ETW2003, pp. , 25-28 May 2003, Maastricht, The Netherlands.