Passive Modeling – Wire Resistance Test Automation
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The document details the development of an automated wire resistance testing method aimed at design kit verification. It discusses creating a test definition that can be utilized across technologies, using a simple model to compute wire resistance based on device geometry. Results indicated excellent agreement between measurements and models for both thin and thick metal resistance, ensuring low measurement uncertainty.
Passive Modeling – Wire Resistance Test Automation
- 1. Passive Modeling – Wire Resistance Test Automation Phillip Corson August 2013 August 20131
- 2. ∗ Goal ∗ Background ∗ Development ∗ Results ∗ Summary August 20132 Agenda
- 3. ∗ Automate the I/V testing of wires for design kit verification ∗ Use device geometry and design level already available to the test executive at test time ∗ Create a test definition useable across technologies ∗ Test definition requires only a single definition of technology specific parameters August 20133 Goal
- 4. ∗ Wire resistance dependent on level, width, and device length and space ∗ Current must not create self heating ∗ Testing done with current in 1 – 2 – 5 steps ∗ Net: forced current can be different on each device with hundreds of devices to test August 20134 Background
- 5. ∗ Need “simple model” for wire resistance ∗ Start with a table of resistance values from the technology definition derived from all the process factors that influence wire resistance August 20135 Development - model for test Level on-wafer line width line resistance per unit length 1 M1 0.40 18.3 2 M1 0.60 10.5 3 M1 0.80 7.0
- 6. ∗ Need “simple model” for wire resistance ∗ Direct fit is a power function – not desirable August 20136 Development - model for test (cont.) – Need function with less potential error, particularly at the range limits Wire Resistance y = 0.2826x -1.2615 R 2 = 0.9961 Line Width Resistance
- 7. ∗ Need “simple model” for wire resistance ∗ Solution: Transform line width to squares/unit length August 20137 Development – model for test (cont.) – Result: Well behaved second order polynomial with small coefficients and exceptional correlation Wire Resistance y = 0.0141x 2 + 0.3971x - 0.2421 R 2 = 0.9992 Squares/unit length Resistance
- 8. ∗ Use the “simple Model” for wire resistance combined with the known device width and length, and target voltage drop to compute target current ∗ Set the fitting coefficients from “simple model” and target voltage drop aspects in the test definition ∗ Set the number of points in the sweep ∗ Use high precision DVM to measure voltage across the Kelvin terminals ∗ Force currents set by the test script on a device instance basis ∗ DVM measurement and force current saved for each sweep point August 20138 Development – test script
- 9. August 20139 Results - wire resistance, thin metal Resistance Line Width Narrow Thin Metal Resistance Measurement Model Nominal Model Maximum Model Minimum ∗ Measurements and model in excellent agreement
- 10. ∗ Measurements and model in excellent agreement August 201310 Results - wire resistance, thick metal Resistance Line Width Wide Thick Metal Resistance Measurement Model Nominal Model Maximum Model Minimum
- 11. ∗ New test script process ∗ Single test definition customized with aspects ∗ Force values computed at test execution time for each device instance ∗ Low measurement uncertainty ∗ Excellent agreement between measurement and model for thin and thick metal August 201311 Summary