Consolidated Strap Cell Layout for Uniform SRAM Well Potential
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Solution Overview
Problem
Existing designs of strap cells and filler cells in semiconductor memory devices, such as SRAM, have not adequately addressed the challenges of uniform charge distribution and performance uniformity across memory cells, particularly at advanced technology nodes, leading to issues with scalability, manufacturability, reliability, power efficiency, and area density.
Innovation Solution
Incorporation of transition cells, including strap cells and edge cells, with well straps configured to stabilize well potential and facilitate uniform charge distribution, along with strategic consolidation of these cells to reduce the overall width of memory blocks, enhancing scalability and compliance with design rule check guidelines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If strap cells are added to stabilize well potential and achieve uniform charge distribution, then performance uniformity across memory cells is improved, but device complexity and area overhead increase
Solution Approach 1:
The patent combines multiple strap cells into a single consolidated strap cell structure that serves the same well potential stabilization function for multiple memory cell columns. This merging approach maintains the performance uniformity benefits while reducing the total number of individual strap cells required, thereby decreasing device complexity and area overhead
Solution Approach 2:
The consolidated strap cell is designed to serve multiple memory cell columns simultaneously, making it a multi-functional structure. This universal strap cell configuration allows a single structure to perform the well potential stabilization function for several columns, reducing overall device complexity while maintaining performance uniformity across all served columns
2Stability of the object's composition
If strap cells are added to facilitate uniform charge distribution, then charge distribution uniformity is improved, but area overhead increases
Solution Approach 1:
Multiple strap cells are merged into a single consolidated structure that provides charge distribution uniformity across multiple memory cell columns. This consolidation maintains the necessary charge distribution uniformity while occupying less total area than multiple separate strap cells would require
Solution Approach 2:
The strap cell structure is extended in the vertical dimension by incorporating multiple tiers of transistors stacked above each other. This three-dimensional configuration allows the single strap cell to serve multiple columns while minimizing the horizontal footprint, thereby reducing area overhead while maintaining charge distribution uniformity
3Productivity
If transition cells are strategically consolidated to reduce memory block width, then scalability is improved, but device complexity increases
Solution Approach 1:
The patent consolidates multiple transition cells (including strap cells and edge cells) into a single integrated structure at the boundary of memory blocks. This merging enables the reduced memory block width achievement while maintaining all necessary transition functions, thereby improving scalability without proportionally increasing device complexity
Solution Approach 2:
The consolidated transition cell structure is divided into functional segments, each handling specific transition functions for adjacent memory blocks. This segmentation allows the complex multi-functional structure to be organized into manageable modules, making the increased device complexity more tractable while maintaining scalability benefits
Data Source
AI summary
A memory device includes a first memory array disposed over a substrate, a second memory array disposed over the substrate and separated from the first memory array along a first direction, and a strap cell defined in the substrate and interposed between the first memory array and the second memory array. The strap cell includes a first boundary abutting the first memory array, a second boundary abutting the second memory array, a p-type well strap interposed between the first boundary and the second boundary along the first direction, and an n-type well strap spaced from the p-type well strap along the second direction. The first boundary and the second boundary extending along a second direction perpendicular to the first direction. The p-type well strap is coupled to a first power supply voltage, and the n-type well strap is coupled to a second power supply voltage.