Multilayer Passivation for SAW Electrodes With High k2

The passivation structure is divided into multiple layers with different materials and functions. The first passivation layer (silicon nitride) provides primary protection with higher hardness, while the second passivation layer (silicon oxide) provides additional protection with lower hardness. This segmentation allows each layer to be optimized for specific functions, achieving sufficient protection without requiring excessive total thickness that would degrade electromechanical coupling and thermal dissipation.

Different regions of the passivation structure have different properties. The first passivation layer has higher hardness for mechanical protection, while the second layer has lower hardness for stress management. The thicknesses are locally optimized - the first layer is thinner than the second layer - to balance protection needs with maintaining electromechanical coupling coefficient and thermal dissipation performance.

The passivation structure is segmented into multiple layers with different thermal properties. The first passivation layer (silicon nitride) and second passivation layer (silicon oxide) have different thermal conductivities and heat capacities. This segmentation allows heat to be managed more effectively through the layered structure, preventing excessive heat buildup while still providing adequate mechanical protection.

The passivation structure uses composite materials - silicon nitride and silicon oxide - which have different thermal and mechanical properties. This composite approach allows the structure to provide mechanical protection while managing thermal dissipation, as the different materials complement each other's properties to balance protection and heat management functions.