Dynamic Electroluminescence Imaging (DEI)

Electroluminescence is the light generated by the passage of electric current through a device. A LED is an example of this, but even the very small currents that flow, as CMOS devices switch, produce measurable luminescence. In collaboration with Carleton University, MuAnalysis hosts a microscope and a sensitive high gain photodetector to track individual photons in both space and time. Micrograph images are recorded as a function of time, typically with up to 100 picosecond resolution. In other words, DEI can make a movie of the operation of microelectronic devices.

Time integration of a movie showing a portion of a memory device. The boxes identify regions of the device, which have been extracted for the construction of timing diagrams.

Histogram of switching transients at locations identified above. The bar colours correspond to those of the boxes, and demonstrate the time characteristics of these regions.

Typical applications

Determination of root-cause failure through

• Time-resolved image analysis during operation of circuit or discrete device
• Waveform determination without physical contact

Design verification
IP (Intellectual Property) validation

Equipment

Quantar Technology Mepsicron-II^TM single photon imaging detector system, with data analysis Karl Süss PM-8 probe station

The Mepsicron-II^TM system is functionally equivalent to a circular array of single photon counting photomultiplier tubes of size 60 X 60 micron, each with a dark count of < 10^-2 counts per second, spectral range of 200 to 1000 nm, quantum yield approaching 10% and 100 picosecond time resolution. With the detector mounted on the microscope of a probe station, MuAnalysis can analyze the luminescence image of an operating device or circuit with the resolution described above. The instrument is sufficiently sensitive that luminescence microscopy images can be observed in real time. This makes alignment and searches over an exposed die particularly easy.

A special feature of DEI is the ability to dissect a time-resolved luminescence image stream. In this way timing diagrams for particular regions of interest can be constructed.

DEI can be performed from the back side of devices, minimizing sample preparation time for complex circuits covered by many levels of metallization.