BA 8

Bond aligners are used to bring patterned substrates into precise relative position before bonding. Bond aligners belong to the alignment and exposure-related part of microfabrication, where optical observation of alignment marks supports accurate registration between substrates. Bond aligners are typically used when wafer-to-wafer or substrate-to-substrate placement accuracy matters before a subsequent bonding step.

Bond aligners generally image alignment marks on opposing substrates and let an operator or control system bring those marks into registration before contact or transfer to a bonding stage. Infrared viewing is commonly used in this equipment class when alignment targets must be seen through materials that are not fully transparent in visible light. Top-side and bottom-side alignment modes support different stack orientations and target locations on the substrates.

In a typical process sequence, bond alignment comes after the substrates have already been prepared with films, patterns, or features that must be registered to each other. Bond alignment comes before the final bonding operation, where the aligned pair is joined by a chosen bonding method. The step is important in flows that stack functional layers or combine separately processed substrates into a single assembly.

Bond aligners are used in processes where features on separate substrates must be overlaid before permanent joining. Typical uses include stacked device construction, sensor integration, packaging flows, and microstructure assembly. The equipment class is relevant wherever alignment accuracy affects the final electrical, optical, mechanical, or fluidic relationship between bonded layers.