Process development and integration of hybrid bonding for wafers with multi-type bonding pads

Abstract

Hybrid bonding technology is widely concerned in the field of advanced packaging, due to its high density and short distance. Current research focuses on the implementation of wafers with only one type of pad. However, integrating multi-type pads on the same wafer introduces huge challenges in process control, especially ensuring tight concave variations across all copper pads during the CMP step. In this work, the novel hybrid bonding process for wafers featuring pads of various sizes and shapes has been developed and verified. Characterization techniques such as AFM, SEM, TEM and EDS were adopted to conduct in-depth analysis of the interest region before and after bonding, confirming the effectiveness of the strategy. These results can provide guidance for flexibilizing pad design, optimizing bonding process, and enhancing bonding quality under complex scenarios.