Fin-Based Well Strap Structure for Lower SRAM Pickup Resistance
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Solution Overview
Problem
As FinFET technologies progress to smaller technology nodes, fin-based well strap cells in SRAM arrays experience increased well pickup resistance and reduced latch-up performance due to decreasing fin dimensions, leading to non-uniform performance among SRAM cells.
Innovation Solution
Increasing the width of fin-based well strap fins relative to FinFET fins reduces well pickup resistance without affecting the desired characteristics of the FinFETs, thereby improving latch-up immunity in SRAM arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fin dimensions are decreased to progress to smaller technology nodes, then device integration density is improved, but well pickup resistance increases and latch-up performance deteriorates
Solution Approach 1:
The patent applies different fin widths to different functional regions: narrow fins (e.g., 5-10 nm) are used in SRAM cells for high density, while wide fins (e.g., 15-30 nm) are used in well strap regions for low resistance. This local differentiation allows each region to be optimized for its specific function without compromising overall system performance.
Solution Approach 2:
The invention changes the geometric parameter (fin width) of the well strap fins relative to standard FinFET fins. By increasing the fin width parameter in well strap regions, the resistance is reduced while maintaining the scaled dimensions in computational regions, directly addressing the latch-up performance issue.
2Stability of the object's composition
If fin-based well strap cells are implemented to stabilize well potential, then uniform charge distribution is achieved, but pick-up resistance increases due to decreased fin dimensions
Solution Approach 1:
The patent implements well strap fins with locally optimized dimensions that differ from standard FinFET fins. The well strap fins have increased width specifically in the strap region to reduce resistance, while maintaining appropriate dimensions in cell regions. This local quality differentiation enables simultaneous achievement of well potential stability and low pick-up resistance.
Solution Approach 2:
The invention addresses the resistance issue by modifying the lateral dimension (width) of the fin structure in well strap regions, compensating for the reduced vertical current drive capability caused by scaled-down dimensions. This dimensional adjustment in the well strap region provides alternative current paths with lower resistance.
Data Source
AI summary
Fin-based well straps are disclosed for improving performance of memory arrays, such as static random access memory arrays. An exemplary integrated circuit (IC) device includes a FinFET disposed over a doped region of a first type dopant. The FinFET includes a first fin having a first width doped with the first type dopant and first source/drain features of a second type dopant. The IC device further includes a fin-based well strap disposed over the doped region of the first type dopant. The fin-based well strap connects the doped region to a voltage. The fin-based well strap includes a second fin having a second width doped with the first type dopant and second source/drain features of the first type dopant. The second width is greater than the first width. For example, a ratio of the second width to the first width is greater than about 1.1 and less than about 1.5.