Backside-Connected SRAM Layout for Latch-Up-Free Edge Shrink

The patent extracts and removes the tap cells from the edge region, eliminating the harmful P-N junctions that cause latch-up issues. Instead of including tap cells to prevent latch-up, the invention uses a different approach by forming the bit cell array directly on the substrate without requiring separate tap cell structures, thereby reducing geometry size while maintaining reliability

Instead of the conventional approach of adding tap cells to prevent latch-up (positive action), the patent inverts the approach by deliberately creating P-N junctions within the bit cell structure itself that serve the protective function, thereby eliminating the need for separate tap cells and reducing overall geometry size

The patent extracts tap cells from the edge region configuration, removing the structures that consume area without contributing to core memory functionality. By eliminating these non-functional elements and integrating latch-up protection directly into the bit cell structure, the functional density is improved as more of the chip area can be used for active memory cells

The patent makes the bit cell structure itself multi-functional by incorporating P-N junctions that simultaneously serve as part of the memory cell operation and as latch-up protection. This eliminates the need for separate dedicated protection structures, allowing the same area to serve both storage and protection functions, thereby increasing functional density