Novel Characterization Method of Chip Level Hybrid Bonding Strength

Abstract

A new characterization method for interfacial adhesion between die to die hybrid bonding interface at chip level is developed to evaluate and analyze the adhesion strength. Die to wafer or die to die hybrid bonding and stacking is very promising scheme for the next 2.5D and 3DIC Heterogeneous. However, there is no proven methodology or guideline to characterize the die level hybrid bonding strength which is very much dependent on the surface treatment process parameters, the physical and chemical characteristics of the bonding interfaces and particles and so on. To improve the quality and reliability of the die level hybrid bonding interface, it is crucial to identify well defined characterization methodology, especially for the thin die case which is no more applicable by using conventionally used die shear test method. In this paper, the authors developed novel characterization method of die level hybrid bonded interface strength by applying the single cantilever method using thin die with a thickness of $100\ \mu\mathrm{m}$. To optimize the test specimen design and testing condition, the finite element analysis (FEA) is performed. Using the optimized methodology, a series of experiments for characterizing the die to die bonding strength are conducted at various load-point lengths, bonding lengths and annealing temperatures. Based on the FEA and experimental data, the limitations and prospects of the developed characterization method are discussed in detail.