FIR Sensor Via Formation on Thinned Substrates Without Breakage

The substrate is thinned before via formation, but the critical strengthening action (forming the inverted T-shape by selective cap layer removal) is performed after bonding to provide structural support during the subsequent via etching process. This preliminary thinning followed by post-bonding structural reinforcement resolves the contradiction by enabling fast etching while preventing substrate damage through timing the structural strengthening after bonding.

The cap layer acts as an intermediary structural element that provides mechanical support to the substrate. By selectively removing portions of the cap layer to form the inverted T-shape, the substrate gains structural reinforcement at critical locations, allowing the thinned substrate to withstand the via etching process without damage.

The substrate thinning is performed as a preliminary step before bonding, establishing the optimal thickness for via etching reliability. The structural reinforcement through selective cap layer removal is then performed after bonding to protect the thinned substrate from damage during subsequent processing, resolving the contradiction between achieving reliable via etching and preventing substrate damage.

The inverted T-shape structure formed by selective cap layer removal serves as a protective cushion or reinforcement structure that prevents substrate damage. This structural reinforcement is established before the via etching process, cushioning the thinned substrate against potential damage while maintaining high via etching reliability.

The cap layer is segmented or selectively removed in specific regions to form the inverted T-shape, rather than uniformly thinning the entire cap layer. This segmentation approach achieves the sealing capability by creating the necessary geometric shape while using standard photolithography and etching processes, thereby limiting the increase in manufacturing complexity to routine patterning operations.

The cap layer is selectively thinned only in the peripheral regions to form the inverted T-shape, while the central window region maintains its original thickness. This local quality approach provides sealing capability where needed (at the periphery) without unnecessarily complicating the manufacturing of the entire device, as only specific regions require selective removal.

The substrate is thinned before via formation, and the inverted T-shape structure is formed by selective cap layer removal before via etching. These preliminary actions establish precise geometric references and control the substrate properties, enabling accurate via placement with standard manufacturing precision. The preliminary structuring reduces the tolerance requirements for subsequent via formation.

The substrate thickness is changed by thinning it to an optimized value that balances via etching speed with structural integrity. This parameter change (thickness control) enables precise via placement and formation by creating optimal etching conditions, thereby achieving backside contact integration with manageable manufacturing precision requirements while maintaining compact device footprint.