4CPP FinFET SRAM Layout for Decongested Bit Line Routing

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Solution Overview

Problem

Traditional 4Cpp FinFET SRAM architectures face congestion in metal layers due to bit lines and complementary bit lines running in the same track, requiring additional processing steps to resolve routing issues, and involve fin cuts and shared contacts that complicate manufacturing.

Innovation Solution

A 4Cpp FinFET SRAM architecture that eliminates fin cuts and shared contacts, allowing bit lines and complementary bit lines to be in separate tracks, simplifying metal layer routing and reducing processing complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If bit lines and complementary bit lines are routed in the same track in traditional 4Cpp FinFET SRAM architecture, then metal layer routing density is improved, but metal layer congestion increases and requires extra processing steps

Engineering Contradiction:

Improvemetal layer routing densityVSAvoidmetal layer congestion and processing complexity

Core Design Contradiction:

Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent separates bit lines and complementary bit lines into different metal layer tracks, transitioning from a single-track routing approach to a multi-track approach. This dimensional separation in the metal layer structure eliminates routing congestion and removes the need for additional processing steps to resolve conflicts, while still achieving high routing density through organized multi-layer utilization

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If fin cuts and shared contacts are implemented in 4Cpp FinFET architecture, then transistor integration is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvetransistor integration efficiencyVSAvoidmanufacturing process complexity

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent eliminates the need for fin cuts and shared contacts by extracting these complex manufacturing requirements from the process. The design achieves high transistor integration through alternative structural arrangements that maintain manufacturability, removing the disturbing elements (fin cuts and shared contacts) that complicated the manufacturing process

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS12520470B24CPP SRAM cell and array

Publication Date: 2026.01.06 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A static random access memory (SRAM) cell includes a four-contact polysilicon pitch (4Cpp) fin field effect transistor (FinFET) architecture including a first bit-cell and a second bit cell. The SRAM cell includes a first bit line and a first complementary bit line, wherein the first bit line and the first complementary bit line are shared by the first and second bit-cells of the SRAM cell. The SRAM cell includes a first word line connected to the first bit cell, and a second word line connected to the second bit cell.