Magnetic Microscopy for 3D Structures: Use of the Simulation Approach for the Precise Localization of Deep Buried Weak Currents

Abstract

With the innovations in packaging technologies which have taken place over the last decade, new assemblies often include an increasing number of dies inside a single package. This is exactly what was predicted by the More than Moore’s paradigm: as the integration of ICs increases, the heterogeneity of the devices found in a single package increases. As a result, the number of potential failures which can appear at assembly level has increased exponentially. At present, no technique has been able to precisely localize defects which are deep inside a complex package. For this reason, a new technique for failure localization for three-dimensional structures is needed. In this paper the technique proposed, based on the coupling of magnetic measurements and simulations, is applied to a three-dimensional structure to precisely localize the current path which is buried deep inside it. A new method, based on parameters fittings of magnetic simulations, is then applied in order to accurately evaluate the distance between the current and the sensor.

3D current path in stacked devices: Metrics and challenges

“…For the case of studying 3D stacked devices, the sensor chosen was the superconducting quantum interference device (SQUID), as the SQUID is very sensitive and can measure magnetic fields as low as 10 -15 T [3], which is critical in order to obtain a good z resolution, especially for deep buried weak currents that are far away from the sensor [5].…”

“…A simulation approach [5][6][7][8] has been used in complementary with MCI for failure localization in integrated circuits (ICs) and 3D devices. This approach uses an iterative algorithm; the current path is built segment by segment.…”