FinFET SRAM Gate Segmentation for Drive Strength Tuning
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Solution Overview
Problem
Conventional SRAM cells with fin field-effect transistors (FinFETs) face limitations in achieving target drive strength ratios due to coarse tuning based solely on the number of fins, which restricts the attainment of specific stability and writability values.
Innovation Solution
The integration of FinFETs with separate gate structures coupled by a metal contact through a dielectric region allows for finer tuning of drive strengths by adjusting the position and width of the dielectric region, enabling non-integer drive strength ratios associated with target stability and writability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of fins in FinFETs is used for tuning drive strength, then the structure is simple and easy to manufacture, but the tuning precision is coarse and cannot achieve non-integer drive strength ratios
Solution Approach 1:
The gate structure is divided into two separate gate structures (first gate structure and second gate structure) that are electrically coupled through a metal contact. This segmentation allows independent control and tuning of drive strengths for different FinFETs, enabling precise adjustment of drive strength ratios beyond what single gate structures can achieve.
Solution Approach 2:
A metal contact is introduced as an intermediary element to electrically couple the first gate structure and the second gate structure. This intermediary enables flexible electrical connection and signal distribution between the separated gate structures, allowing precise control of drive strengths while maintaining manufacturing feasibility.
2Adaptability or versatility
If FinFETs are coupled to a single gate structure, then the device complexity is low, but the drive strength tuning is limited to integer ratios only
Solution Approach 1:
By segmenting the gate structure into multiple independent gates (first gate structure and second gate structure), the system can independently tune drive strengths of different FinFETs. This enables achievement of non-integer drive strength ratios (such as 3:2, 5:3) that are impossible with single gate structures limited to integer ratios.
Solution Approach 2:
The gate structures are designed with adjustable characteristics (such as adjustable width, length, or number of fins) that allow dynamic tuning of drive strengths. This dynamic adjustability enables the system to adapt to various target drive strength ratios by modifying gate dimensions during the design process.
3Manufacturing precision
If the dielectric region width and position are adjusted for fine tuning, then the drive strength precision is improved, but the manufacturing process complexity increases
Solution Approach 1:
The dielectric region is formed between the two gate structures during the fabrication process, establishing the physical separation and electrical coupling path before final gate patterning. This preliminary action enables subsequent precise adjustment of gate dimensions and positions to achieve target drive strength ratios without requiring complex post-fabrication modifications.
Solution Approach 2:
The width and position of the dielectric region are used as adjustable parameters to fine-tune the drive strengths of FinFETs. By varying these geometric parameters during design, precise control over drive strength ratios is achieved while maintaining compatibility with standard fabrication processes.
Data Source
AI summary
In a particular aspect, an integrated circuit includes a first gate structure coupled to a first fin field effect transistor (FinFET) device. The integrated circuit includes a second gate structure coupled to a second FinFET device. The first gate structure and the second gate structure are separated by a dielectric region. The integrated circuit further includes a metal contact having a first surface that is in contact with the dielectric region, the first gate structure, and the second gate structure.