Vertical Memory Array Gate-Last Formation

The patent applies preliminary action by forming sacrificial materials (first and second sacrificial materials) in advance during the stack formation process, before the actual gate and charge-blocking regions are created. These pre-positioned sacrificial materials guide subsequent selective deposition and etching steps, enabling precise control over the final gate structures and charge-blocking regions without requiring complex direct patterning at those stages.

The patent uses sacrificial materials as intermediary elements that facilitate the formation of precise gate structures and charge-blocking regions. These intermediaries are deposited selectively on specific tiers of the stack, then removed to create the desired structures. The sacrificial materials act as temporary mediators that enable precise spatial control during manufacturing, which is then removed after serving its purpose.

The patent segments the memory array formation process into distinct stages with different sacrificial materials for different functions. First sacrificial materials are used for one purpose (forming initial structures), then second sacrificial materials are used for another purpose (forming charge-blocking regions). This segmentation allows each material and process step to be optimized independently, improving control over charge-blocking and charge-storage regions while organizing the complexity into manageable segments.

The patent applies local quality by using different sacrificial materials with different properties at different locations and tiers of the stack. Each sacrificial material is selectively deposited on specific tiers where its particular properties are needed, enabling precise local control over the formation of gate structures and charge-blocking regions without requiring uniform processing across the entire structure.