Stepped Gate SRAM Layout for Charge Dissipation and Short Circuit Prevention
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Solution Overview
Problem
Existing SRAM layouts face challenges with charge accumulation under gate structures, leading to electrical instability and reduced product yield due to close proximity of adjacent gates and potential short circuits.
Innovation Solution
The proposed SRAM layout pattern incorporates diffusion regions with opposite electrical properties adjacent to each other under the gate of each transistor, allowing charge accumulation to be released through these regions, and features a stepped gate structure design to avoid close gate proximity and reduce rounding errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gate structures are placed close together to increase integration density, then productivity is improved, but adjacent gates may short circuit and reliability deteriorates
Solution Approach 1:
The gate structure is segmented into two separate gates (first gate and second gate) with different orientations. The first gate extends in a first direction and the second gate extends in a second direction perpendicular to the first direction. This segmentation allows each gate to be independently formed and positioned, reducing the risk of short circuits while maintaining high integration density through orthogonal arrangement.
Solution Approach 2:
The patent transitions from a single-direction gate arrangement to a two-dimensional orthogonal gate configuration. By introducing gates that extend in perpendicular directions (first direction and second direction), the design utilizes additional spatial dimension to increase integration density without compromising reliability through close proximity in a single line.
2Ease of manufacture
If conventional gate layouts are used, then manufacturing is simpler, but charge accumulates under gates causing electrical instability
Solution Approach 1:
The patent extracts the charge accumulation problem by introducing separate diffusion regions (first diffusion region and second diffusion region) that are electrically connected to the substrate. These diffusion regions act as charge sinks, extracting accumulated charges from under the gate structures and dissipating them to the substrate, thereby eliminating electrical instability while maintaining manufacturing feasibility.
Solution Approach 2:
The diffusion regions serve as intermediary structures between the gate structures and the substrate. They provide a controlled path for charge dissipation, mediating the interaction between the gate electric fields and the substrate to prevent charge accumulation and electrical instability without complicating the manufacturing process.
Data Source
AI summary
The invention provides a layout pattern of static random-access memory (SRAM), which comprises a substrate, wherein a plurality of diffusion regions and a plurality of gate structures are located on the substrate to form a plurality of transistors, wherein the plurality of gate structures comprise a first gate structure, which has a stepped shape when viewed from a top view, and the first gate structure spans a first diffusion region and a second diffusion region to form a first access transistor (PG1), wherein the first diffusion region is adjacent to and in direct contact with the second diffusion region.