Mark Mckinnon’s scientific contributions

Heterogenous integration has led to the development of advanced semiconductor packages with better performance and smaller form factor. Such packages usually comprise of multiple dies and embedded components which are encapsulated with epoxy molding compounds (EMCs) to improve the reliability performance and to protect the die from external impact. However, this increases the difficulty of failure analysis (FA) as the defects may manifest in the embedded components that are covered by EMCs. Suitable sample preparation techniques and workflows are required to remove EMCs to reveal the defects to determine the root cause of failure. This paper explores the use of microwave induced plasma (MIP) etcher to remove EMCs. Tool parameters are varied to understand their effects on the removal rate of EMCs such as underfill.

Advanced packages such as 2.5D will continue to grow in demand as performance increases are needed in various applications. Failure analysis must adapt to the changes in the interfaces, materials and structures being developed and now utilized. Traditional techniques and tools used for selectively removing materials to isolate and analyze defects need to evolve alongside these packages. A CF4-free Microwave Induced Plasma (MIP) process is used to remove underfill (UF) with minimal alteration of other materials on the samples, a process which has become more difficult on 2.5D modules. UF is removed using this MIP process to allow subsequent analysis on interposer interconnects and µbumps in cross-section. SEM inspection, Electron Beam Absorbed Current (EBAC), and FIB are techniques used post cross-sectional UF removal of these 2.5D structures. The benefits of the specific MIP process through case studies are presented. Specifically, the use of an automatic cleaning step and a CF4-free downstream O2 plasma allow easy removal of UF without damaging other structures of interest with little tool recipe development.