Single-Port SRAM Cell Layout With Continuous Active Regions
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Solution Overview
Problem
Existing SRAM cell designs face challenges in scaling down due to discontinuous active regions and densely packed metal lines, leading to leakage and resistive-capacitive delay, which affect processing complexity and efficiency.
Innovation Solution
A single-port SRAM cell design with continuous active regions and spaced-out metal lines, utilizing planar or multi-gate FETs, such as FinFETs or MBC FETs, to reduce RC delay and enhance transistor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active regions are patterned into segments having different lengths, then SRAM cell functionality is achieved, but leakage increases
Solution Approach 1:
The active region is segmented into multiple fins with uniform lengths, where each fin acts as an independent transistor channel. This segmentation allows each fin to be fully controlled by gate structures, eliminating the leakage issues associated with discontinuous active regions of different lengths while maintaining SRAM cell functionality.
Solution Approach 2:
Each fin is equipped with its own gate structure (FG for first gate, SG for second gate) that provides localized control over the active region. This local quality enhancement ensures uniform electrical characteristics across all fins, preventing leakage paths that would occur in designs with discontinuous active regions.
2Productivity
If metal lines are densely packed, then functional density increases, but resistive-capacitive delay increases
Solution Approach 1:
The design transitions from planar metal line routing to three-dimensional vertical stacking with multiple metal layers (M1, M2, M3). This dimensional change allows metal lines to be spaced out within the vertical dimension while maintaining high functional density through layered interconnect structures, thereby reducing RC delay.
Solution Approach 2:
Multiple metal layers are nested vertically above each other, with each layer providing additional routing capacity. This nesting approach allows dense interconnect functionality while maintaining adequate spacing between lines on each individual layer, reducing resistive-capacitive effects.
3Productivity
If geometry size is decreased, then production efficiency increases and costs decrease, but processing complexity increases
Solution Approach 1:
The fin-based active region structure serves multiple functions simultaneously: it provides the transistor channel, defines the active area, and enables scalable geometry reduction. This universal structure simplifies processing by eliminating the need for complex patterning of discontinuous active regions while maintaining scalability to smaller geometries.
Solution Approach 2:
The design uses uniform fin length as a consistent geometric parameter that can be easily scaled. By changing the fin length parameter uniformly across all fins in the structure, the design achieves scalability to smaller geometries without increasing processing complexity, as the same fabrication processes can be applied regardless of the specific dimension.
Data Source
AI summary
Memory devices are provided. A memory device according to the present disclosure includes a first pull-down device (PD-1), a second pull-down device (PD-2), a first pass-gate device (PG-1), and a second pass-gate device (PG-2) disposed in a first p-well on a substrate, and a first pull-up device (PU-1), a second pull-up device (PU-2), a first isolation device (IS-1), and a second isolation device (IS-2) disposed in an n-well adjacent the first p-well. The PD-1, the PD-2, the PG-1, and the PG-2 share a first active region. The PU-1, the PU-2, the IS-1, and the IS-2 share a second active region. A first gate of the IS-1 and a second gate of the IS-2 are coupled to a positive supply voltage. A drain of the PU-1 and a drain of the PU-2 are coupled to the positive supply voltage (CVdd).