For Integrated Circuit (IC) wafer backend development, process developers have to design robust backend structures that guarantee both the functionality and reliability during waferfab processes, packaging, qualification tests and usage. Among many other possible failure modes, it is found that thermo-mechanical (thermal, mechanical and thermo-mechanical) related failures account for a large part of total failures of backend structures. Due to the rapid development of Cu/Low-k technologies and the inherited weakness of thermo-mechanical properties of Cu/Low-k stacks, thermo-mechanical reliability is becoming one of the major bottlenecks. The solutions of this problem relied on, among others, the development and implementation of innovative and integrated thermomechanical design and qualification methods. This paper summarises parts of our research results of developing methodologies, models and tools that can be used to design and qualify the wafer backend structures by integrating the design targets and requirements from both waferfab backend processes and packaging parameters.
['G.Q. Zhang', 'J. Bisschop']
Integrated thermo-mechanical design and qualification of wafer backend structures