TSV Alignment Marks for Substrate Misalignment

The patent combines the formation of functional TSVs and alignment-mark TSVs into a single integrated process. Both types of TSVs are formed simultaneously through the substrate using the same via formation steps, eliminating the need for separate alignment mark formation processes. This merging approach reduces manufacturing complexity while maintaining alignment accuracy, as the alignment marks are created as an inherent part of the TSV fabrication rather than as a separate post-processing step.

The patent creates alignment-mark TSVs that are precise copies of the functional TSVs in terms of formation process and structural characteristics. These alignment-mark TSVs serve as exact replicas that can be reliably detected by the infrared alignment system, providing known reference positions that compensate for the system's inherent accuracy limitations. The copying approach ensures that alignment marks have the same optical and physical properties as functional TSVs, enabling accurate alignment despite substrate thickness variations.

The patent introduces alignment-mark TSVs as intermediary reference structures that mediate between the physical substrate and the alignment measurement system. These intermediary markers provide stable, detectable reference points that are less sensitive to substrate thickness variations than direct TSV measurements. The alignment-mark TSVs act as buffer elements that translate the physical geometry into reliable alignment signals, compensating for the imprecision introduced by thinned substrate variations.