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AbstractsThis work provides for the first time an experimental assessment of the impact of thermo-mechanically induced stresses by copper through-silicon vias, TSVs, on fully depleted Bulk FinFET devices. Both n and p type FinFETs are significantly affected by TSV proximity, exhibiting lower impact on drive current with respect to the planar devices. The obtained results are in agreement with the thermo-mechanical models for Cu-TSV and are supported by the 4 point bending stress calibration. Fig. 1: Cross sections of a through silicon via and a FinFET device at close proximity (a, b). The FinFET device has 40nm fin height, 20nm fin width, 1nm chemical oxide, followed by atomic layer deposition of 1.8nm HfO2 insulator and 5nm TiN work function metal gate (c,d)

3D die stacking is a promising technique to allow miniaturization and performance enhancement of electronic systems. Key technologies for realizing 3D interconnect schemes are the realization of vertical connections, either through the Si die or through the multilayer interconnections. The complexity of these structures combined with reduced thermal spreading in the thinned dies complicate the thermal analysis of a stacked die structure. In this paper a methodology is presented to perform a detailed thermal analysis of stacked die packages including the complete back end of line structure (BEOL), interconnection between the dies and the complete electrical design layout of all the stacked dies. The calculations are performed by 3D numerical techniques and the approach allows importing the full electrical design of all the dies in the stack. The methodology is demonstrated on a 2 stacked die structure in a BGA package. For this case the influence of through-Si vias (TSVs) on the temperature distribution is studied. The modeling results are experimentally validated with a dedicated test vehicle. A thermal test chip with integrated heaters and diodes as thermals sensors is used to successfully validate the detailed temperature profile of the hot spots in the top die of the die stack.

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