This paper discusses the development of an extensible programmatic workflow that leverages evolving technologies in 2D/3D imaging, distributed instrument control, image processing, and automated mechanical/chemical deprocessing technology. Initial studies involve automated backside mechanical ultra-thinning of 65nm node IC processor chips in combination with SEM imaging and X-ray tomography. Areas as large as 800μm x 800μm were deprocessed using gas-assisted plasma FIB delayering. Ongoing work involves enhancing the workflow with “intelligent automation” by bridging FIB-SEM instrument control and near real-time data analysis to establish a computationally guided microscopy suite.
The visible approach of optical Contactless Fault Isolation (VIS-CFI) serves the perspective of application in FinFET technologies of 10 nm nodes and smaller. A solid immersion lens (SIL) is mandatory to obtain a proper resolution. A VISCFI setup with SIL requires a global polishing process for sub-10 µm silicon thickness. This work is the first to combine all these necessary components for high resolution VIS-CFI in one successful experiment. We demonstrate Laser Voltage Imaging and Probing (LVI, LVP) on 16/14 nm technology devices and investigate a focus depth dependence of the LVI/LVP measurement in FinFETs.
Anticipating the end of life for IR-based failure analysis techniques, a method of global backside preparation to ultra-thin remaining silicon thickness (RST) has been developed. Ultra-thin RST enables VIS light techniques such as laser voltage probing. In this work we investigate the lower RST limit due to sub-surface damage from grinding and a one-step polishing method to achieve 3 um RST (+/- 0.8 um) over 121 mm2 die (11 x 11 mm) test package as well as 5 um (+/- ) over 109.2 mm2 (8.0 x 13.7mm) active device.
Visible light laser voltage probing (LVP) for backside improved optical spatial resolution is demonstrated on ultrathinned bulk Si samples. A prototype system for data acquisition, a method to produce ultra-thinned bulk samples as well as LVP signal, imaging, and waveform acquisition are described on bulk Si devices. Spatial resolution and signal comparison with conventional, infrared LVP analysis is discussed.
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