| CPC G01R 31/311 (2013.01) [H01S 3/06716 (2013.01); H01S 3/09 (2013.01)] | 13 Claims |

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1. An integrated circuit (IC) wafer or chip imaging method comprising:
applying a pulsed optical beam having pulse duration of 900 femtoseconds or lower on a backside of a substrate of the IC wafer or chip;
focusing the pulsed optical beam at a focal point in an active layer disposed on a frontside of the substrate, wherein a photon energy of the pulsed optical beam is lower than a bandgap of the substrate and is lower than a bandgap of the active layer, and wherein photons of the optical beam are absorbed at the focal point in the active layer by nonlinear optical interaction to generate carriers at the focal point in the active layer; and
measuring an output signal produced by the IC wafer or chip in response to the carriers injected at the focal point in the active layer;
repeating the applying of the pulsed optical beam and the focusing of the pulsed optical beam at a focal point and the measuring of the output signal for each focal point in the active layer of a grid of focal points in the active layer; and
generating an image of the IC wafer or chip from the output signals measured at the focal points of the grid of focal points.
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