Hybrid bonding is a revolutionary semiconductor packaging technology that enables direct bonding between two wafers or chips. This process simultaneously bonds both metal interconnects and dielectric materials, creating high-density connections with excellent electrical and mechanical properties.
Surface preparation is critical for successful hybrid bonding. The process begins with chemical mechanical polishing, or CMP, which removes surface irregularities and creates an atomically smooth surface. This is followed by thorough chemical cleaning to remove any contaminants or particles that could interfere with the bonding process.
The alignment and bonding process requires extreme precision. First, the wafers are aligned using optical alignment markers with nanometer accuracy. Once properly aligned, controlled pressure and heat are applied simultaneously. This creates both mechanical contact and activates the bonding mechanisms between metal pads and dielectric layers.
The hybrid bonding process involves two distinct but simultaneous bonding mechanisms. First, metal-to-metal diffusion bonding occurs between the copper pads, where atoms diffuse across the interface under heat and pressure. Second, oxide-to-oxide covalent bonding forms strong chemical bonds between the dielectric layers. These dual mechanisms create both electrical connectivity and mechanical strength.