Redistribution Layer Buffer Structure for MIM Capacitor Reliability

The patent segments the passivation layer into multiple layers (first passivation layer and second passivation layer) with different materials and stress properties. This segmentation allows each layer to perform specific functions: the first passivation layer provides initial protection while the second passivation layer with compressive stress counteracts recess loading, thereby maintaining reliability as devices are scaled down and functional density increases.

The patent employs composite material structures by combining different dielectric materials with distinct stress characteristics. The first passivation layer and second passivation layer are made of different materials that, when combined, provide both mechanical protection and stress management. This composite approach enables the structure to withstand the increased recess loading that occurs during device scaling while maintaining dielectric integrity and preventing breakdown voltage failure.

The patent applies beforehand cushioning by forming the first passivation layer prior to the barrier layer removal process. This pre-formed passivation layer acts as a protective cushion during the aggressive etching process needed to remove the barrier layer and create the opening. It absorbs the mechanical stress and prevents direct damage to underlying structures, thereby enabling easy opening formation while maintaining passivation layer integrity.

The first passivation layer serves as an intermediary between the barrier layer removal process and the underlying structures. During the etching process that removes the barrier layer to form the opening, the first passivation layer mediates the mechanical stresses and protects the underlying electrode structures from damage. This intermediary layer enables the manufacturing process to proceed easily while preserving the integrity of critical underlying components.

The patent divides the passivation structure into segmented layers with distinct functions. The first passivation layer provides base protection and adhesion, while the second passivation layer with compressive stress specifically addresses stress management. This segmentation allows each layer to be optimized for its specific function, achieving superior adhesion and stress management without requiring excessive complexity in the overall device design.

The patent applies parameter changes by varying the stress state of different passivation layers. The first passivation layer has one stress characteristic while the second passivation layer is specifically designed with compressive stress. By changing the stress parameter between layers, the structure achieves effective stress management and enhanced adhesion, demonstrating how parameter variation can improve reliability without proportionally increasing device complexity.