DBI Wafer-to-Wafer Hybrid Bonding

During processing, industry-standard dielectrics surfaces such as silicon oxide and silicon carbide nitride, with embedded metal bond pads that are typically of copper or nickel, are polished to achieve minimal surface roughness. Simultaneously, the metal bond pads are slightly dished. Polishing and dishing are readily achieved using standard chemical mechanical polishing (CMP) tools. Nitrogen-based chemistries are applied through conventional plasma etch tools. Prepared wafers can then be simply aligned and placed together, resulting in the spontaneous formation of strong chemical bonds between the prepared surfaces. After a moderate batch anneal, the DBI bond pads expand together to form a homogeneous metallic interconnect with grain growth across the bond interface. The chemical bond between oxides is significantly strengthened, ensuring high reliability without requiring underfill.