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Testing of High-Power IGBT, Power Transistor, Power Diode, and MOSFET Semiconductor Devices

There’s an art to semiconductor development and testing thanks to the competing constraints imposed by time, money, precision, repeatability, and test coverage.  Teams that are able to leverage accelerated lifetime testing and failure diagnosis gain a valuable advantage over their more traditional competitors.  This type of testing can provide die, packaging, and process engineers a deep and broad understanding of their products while building confidence in their design and production processes.  Critical aspects of this understanding include high-level functional testing and low-level, layer-by-layer characterization of the semiconductor substrates.

Challenges:

  • Estimation of high-power semiconductor product lifetimes
  • Identification of high-power semiconductor package defects

Values:

  • Accurate layer-by-layer characterization of a semiconductor stackup
  • Increased understanding of semiconductor designs and processes
High-level failure mode characterization throughout a device’s lifetime requires testing methods that approximate end-use applications of the device in terms of cooling, environment, and cycling.  This may mean powering through thousands or potentially millions of cycles.  It may mean cooling the device in the same way it will be cooled in end-use applications.  It may mean elevating the ambient temperature of the end-use application.  It may mean characterizing the thermal resistance and capacitance of every layer within the semiconductor package from die to heatsink.  For a thorough and realistic test, it likely means all of the above, and ideally it means all of the above at the same time.
 
Recent developments in semiconductor test capabilities mean that all of these aspects can be addressed in a single suite of tests without having to remove the device during the testing process.  This is no mean feat, as low-level layer-by-layer performance, for instance, requires high-precision and sensitive instrumentation while active cycling can require tens of kilowatts of power.  Transient thermal resistance measurements are typically performed at low power, for instance, while reliability testing is performed at high power.  Testing is applicable to laboratory environments during design/development but also to production environments where batch testing can identify process defects before parts reach customers.
 
Repeatability is also of critical importance when characterizing a set of devices, and indeed the latest test methodologies do not rely on thermocouples or other physical instrumentation that are prone to small variations in test setup between tests.  Instead, current, voltage, and even die temperature are captured in terms of precise measurement of electrical power flowing through the device.  One such non-invasive method of measurement is described in JEDEC standard and JESD51-1 where die heating and die temperature sensing are performed without traditional temperature measurement equipment.
 

 

Annotated plot of thermal resistance vs thermal capacitance with cutaway view of the semiconductor stackup.

 

 
Applications and potential users of high-power semiconductor testing are wide-ranging and include the following:
  • Aerospace and defense: aircraft power electronics for propulsion, flight surface control, high power RF systems, component suppliers, digital electronics for flight systems, naval weapons, electric propulsion power system and control electronics.
  • Automotive and transportation: power electronics between battery and motors in EV, HEV, PHEV.  Motor control for rail traction, digital electronics for driver assistance, navigation, and infotainment.
  • Electronics: power electronics component vendors and packaging house for design validation in package and product development, manufacturing process qualification, reliability testing, creation and calibration of thermal models for the supply chain and for thermal design verification, inbound component inspection, and more.

Within those applications (and beyond), modern testing can help calibrate and validate analytic models to better match the real world.  Indeed, designers may even find that there is much value in evaluating existing designs before moving on to new designs.  Stackup tolerances, thermal interface material performance, packaging imperfections, and even PCB mounting variation in existing products can all contribute negatively to overall device functionality.  Understanding the real-world impacts of these existing product variations via testing can inform future designs and help squeeze valuable performance out of those designs.

We’ll explore the details of how the testing described in this technical blog post can be achieved in a future post.  In the meantime, if you’d like to get more information regarding M4’s in-house semiconductor testing capabilities, feel free to reach out to Brian Rotty at brotty@m4-engineering.com or (562) 357-7975.

Brian RottyWritten by Brian Rotty

Brian Rotty is a senior engineer at M4 with a focus on technical program management and embedded systems development.

 
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