edfas.org 5 ELECTRONIC DEVICE FAILURE ANALYSIS | VOLUME 28 NO. 3 EBIRCH PHYSICAL MECHANISMS EBIRCH contrast arises from the interaction between an externally biased conductive path and a localized perturbation introduced by the electron beam. The applied bias establishes a steady-state current in the device under test (DUT), which serves as the measurement baseline. When the electron beam interacts with the DUT, it can induce localized changes in the electrical response, including: Local Heating. The beam deposits energy in highresistance regions or bottlenecks, raising the local temperature and modulating resistance via the temperature coefficient of resistance (TCR) or thermally activated conduction mechanisms. Thermoelectric (Seebeck) Effects. Voltages generated at interfaces between dissimilar materials can add to or subtract from the applied bias, producing apparent resistance changes that may depend on bias polarity. Carrier Generation and Local Charging. In semiconductor or dielectric regions, the electron beam can generate carriers or deposit charge, influencing the measured current or voltage. The resulting EBIRCH signal is a combination of these effects, and their relative contributions depend on the material, geometry, applied bias, and measurement setup. Consequently, the contrast highlights resistive bottlenecks, failures, or other electrical anomalies without assuming a single dominant mechanism.[3] In comparison, optically based techniques such as OBIRCH operate on a similar principle of perturbing a biased DUT, but in this case the laser directly generates local heating, increasing the temperature of the illuminated region and modulating its resistance. Differences between EBIRCH and OBIRCH are primarily in the nature and spatial distribution of energy deposition (electron beam vs laser) and achievable spatial resolution, rather than in the physical origin of the signal.[6] Practical considerations, such as amplifier resolution or signal-to-noise ratio, often dictate the bias level required for EBIRCH measurements; increasing the applied bias enhances the measurable response to localized perturbations without altering the underlying physical mechanisms. EXPERIMENTAL SETUP All experiments reported in this work were conducted on a Kleindiek Nanotechnik (KN) prober shuttle including EBIC amplifier loaded into Zeiss GSEM 460NP and 300 field-emission scanning electron microscopes.[7] The overall system allows simultaneous electrical and electron-beam stimulation through nanomanipulated tungsten probe needles mounted on a KN prober shuttle (PS8). The electrical measurements were performed using either the integrated KN Live Contact Tester (LCT) for preliminary defect characterization up to 100 MΩ, or a Keithley 4200A-SCS parameter analyzer for precise I–V acquisition and bias control. The EBIRCH current was monitored via the EBIC amplifier, capable of detecting current variations from the sub-picoampere to microampere range. The system supports multiple probe configurations with full routing control via an integrated KN signal switching unit, all implemented on a standard 19-in. electronics rack, see Fig. 1. EBIRCH MEASUREMENT CONFIGURATION The experimental geometry employed was a twoneedle EBIRCH. Meaning, a voltage bias was applied to one probe, while the EBIC amplifier monitored the current Fig. 1 From left to right: Standard Kleindiek Nanotechnik rack including micromanipulator nanocontrollers and EBIC amplifier; KN Prober Shuttle 8; schematic of EBIC signal acquisition in the SEM;[6] and simultaneous secondary electron and EBIC signal acquisition.
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