Discrete Active Area Patterning With Multi-Layer Mask Etching

The patent divides the formation of discrete active areas into multiple patterning steps using sequential mask layers. Instead of attempting to directly pattern small-sized discrete active areas in a single photolithography step, the method segments the process into forming continuous active areas first, then using multiple mask layers (second and third mask layers) to progressively divide and separate them into discrete regions. This segmentation approach allows each step to operate at larger, more controllable dimensions while achieving the final small feature sizes, thereby resolving the contradiction between increasing storage density and maintaining manufacturing precision.

The patent applies preliminary action by first forming continuous active areas using a first mask layer before introducing subsequent mask layers to create discrete regions. The second and third mask layers are designed with patterns that overlap and work together to define the final discrete active area locations. This preliminary formation of continuous structures simplifies the overall process by establishing a base pattern that guides subsequent patterning steps, reducing manufacturing complexity while achieving high storage density.

The patent transitions from two-dimensional planar patterning to three-dimensional multi-layer mask structuring. By introducing vertical stacking of multiple mask layers (first, second, and third mask layers) with overlapping patterns, the method achieves small feature size discrete active areas that cannot be obtained through conventional single-layer photolithography. This dimensional transition enables higher production capacity and storage density while maintaining process simplicity through systematic layer-by-layer fabrication.