SRAM Body Contact Layout for Double-Channel Transistors

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Solution Overview

Problem

Conventional static RAM cells require a large number of transistors and consume significant semiconductor area, limiting their packing density and information density, especially when using double channel transistors which do not necessarily reduce area consumption compared to conventional designs.

Innovation Solution

A space-efficient layout is implemented by laterally positioning a body contact between double channel transistors to connect their body regions and source regions with a single contact element, reducing the overall area required for static RAM cells by approximately 50% compared to conventional designs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If conventional transistor architectures are used in static RAM cells, then the circuit functionality is achieved, but the semiconductor area consumption is significant and packing density is limited

Engineering Contradiction:
Improvesemiconductor area consumptionVSAvoidpacking density
Core Design Contradiction:
Area of stationary objectVSProductivity

Solution Approach 1:

The patent merges the body contacts of two adjacent double channel transistors into a single shared body contact structure. This consolidation reduces the total number of body contacts required, thereby decreasing semiconductor area consumption while maintaining proper electrical connection to both transistors' body regions, ultimately improving packing density

Inventive Principle:
Principle #5Merging (Combining)

2Device complexity

If double channel transistors are used to reduce the number of transistor elements, then the transistor count is reduced, but the area consumption does not necessarily decrease compared to conventional designs

Engineering Contradiction:
Improvetransistor element countVSAvoidarea consumption
Core Design Contradiction:
Device complexityVSArea of stationary object

Solution Approach 1:

The patent applies merging by consolidating body contacts for multiple double channel transistors into a single shared structure. This approach maintains the reduced transistor element count advantage while further reducing area consumption through efficient contact sharing, resolving the contradiction between device complexity reduction and area consumption

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The shared body contact structure serves multiple functions: it provides electrical connection to the body region of one double channel transistor and simultaneously provides connection to the body region of another double channel transistor. This multi-functionality reduces the total number of contacts needed, decreasing area consumption while maintaining the benefits of using double channel transistors

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP2319077B1Body contact for SRAM cell comprising double-channel transistors
Publication Date: 2014.12.03 ADVANCED MICRO DEVICES INC
  • EP2319077B1 patent drawingFigure 1a~1b
  • EP2319077B1 patent drawingFigure 1c
  • EP2319077B1 patent drawingFigure 2a

AI summary

A static RAM cell (250) may be formed on the basis of two double channel transistors (200N, 200P) and a select transistor (200S), wherein a body contact may be positioned laterally between the two double channel transistors in the form of a dummy gate electrode structure (205A), while a further rectangular contact (230) may connect the gate electrodes, the source regions and the body contact, thereby establishing a conductive path to the body regions of the transistors. Hence, compared to conventional body contacts, a very space-efficient configuration may be established so that bit density in static RAM cells may significantly be increased.