Infra-Red, In-Situ (IRIS) Inspection of Silicon
This paper introduces the Infra-Red, In Situ (IRIS) inspection method, which uses short-wave IR (SWIR) light to non-destructively "see through" the backside of chips and image them with lightly modified conventional digital CMOS cameras. With a 1050 nm light source, IRIS is capable of constraining macro- and meso-scale features of a chip. This hardens existing micro-scale self-test verification techniques by ruling out the existence of extra circuitry that can hide a hardware trojan with a test bypass. Thus, self-test techniques used in conjunction with IRIS can ensure the correct construction of security-critical hardware at all size scales.
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