Samenvatting
Thermo-mechanical reliability issues are major bottlenecks in the development of future microelectronic components. This is caused by the following technology and business trends: (1) increasing miniaturization, (2) introduction of new materials, (3) shorter time-to-market, (4) increasing design complexity and decreasing design margins, (5) shortened development and qualification times, (5) gap between technology and fundamental knowledge development [1]. It is now well established that for future CMOS-technologies (CMOS065 and beyond), low-k dielectric materials will be integrated in the back-end structures. However, bad thermal and mechanical integrity as well as weak interfacial adhesion result in major thermo-mechanical reliability issues. Especially the forces resulting from packaging related processes such as dicing, wire bonding, bumping and molding are critical and can easily induce cracking, delamination and chipping of the IC back-end structure when no appropriate development is performed [2]. Numerical modeling combined with experiments provides a way to gain more fundamental knowledge and ultimately, to understand, predict and prevent reliability issues. However, numerical methods and models that are readily available in commercial finite element packages are not adequate to model the mentioned phenomena accurately and efficiently. First, due to the inherent scale-difference between application ([cm] to [mm]) and smallest geometry ([μm] to [nm]), a multi-scale method should be used to cover these length-scale differences in an appropriate way. Second, delamination in three-dimensional multi-layered structures should be taken into account. Third, the three-dimensional geometry of the back-end is complex and the individual material and interface properties should be measured accurately. The scope of this paper is on the development of numerical models that are able to predict the failure sensitivity of complex three-dimensional multi-layered structures while taking into account the failure behavior at the local scale of the microelectronic components by means of a multi-scale method. For this purpose, an extended version of the Area Release Energy failure criterion, originally reported in [3, 4] has been developed in combination with a dedicated cohesive zone implementation at local back-end level, reported in [5]. Furthermore, four-point bending experiments have been conducted to obtain the interface strengths of all relevant material combinations. Thus, an efficient 3D damage sensitivity analysis at global, packaging level is performed, while the detailed local modeling results in the prediction of the actual crack initiation and subsequent propagation in the local back-end structures. By using the combined experimental-numerical techniques, crack initiation and propagation is predicted during the wire pull qualification test of Cu/low-k devices.
Originele taal-2 | Engels |
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Titel | Proceedings of the 1st International Congress on Microreliability and Nanoreliability in Key Technology Applications (MicroNanoReliability2007) |
Plaats van productie | Germany, Berlin |
Pagina's | 254-255 |
Status | Gepubliceerd - 2007 |