3D Memory Stack Separation Contacts for Higher Density

The patent transitions from two-dimensional planar memory cells to three-dimensional vertically stacked memory structures. Multiple memory cell layers are stacked in the vertical direction (third direction) above the substrate, enabling higher integration density without requiring finer lateral patterning. This dimensional transition allows achieving high density while avoiding the need for extremely expensive fine-patterning equipment.

The memory device is divided into multiple independent stack structures arranged in an array. Each stack structure contains multiple memory cell layers separated by intermediate layers. This segmentation allows parallel fabrication processes and reduces the complexity of forming fine patterns across the entire device, thereby lowering manufacturing costs while maintaining high integration density.

By moving to three-dimensional stacking, the patent reduces dependence on lateral pattern precision. The vertical stacking approach uses thicker layers and larger lateral dimensions that are easier to fabricate with standard precision equipment, while achieving high density through the third dimension rather than through extremely fine two-dimensional patterning.

The patent changes the critical dimensions from lateral (two-dimensional) to vertical (three-dimensional). The memory cell size is determined by vertical layer thickness and stack height rather than lateral feature size. This parameter change allows using larger, more easily manufactured dimensions while achieving equivalent or higher density, thereby reducing manufacturing precision requirements.