Semiconductor Integrated Circuit Device Well Proximity Effect Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The well proximity effect in semiconductor integrated circuits leads to variations in transistor characteristics due to impurity reflection and scattering, causing mismatched circuit operation and reduced yield, especially in smaller microstructures where layout rules narrow the space between transistors and wells, resulting in defective products and decreased competitiveness.
Innovation Solution
The solution involves arranging standard cell rows with N wells and P regions such that the positions of these wells are switched every other row, and the distance from transistors to the ends of the wells is broadened to be greater than or equal to the shared well width, or using dummy cell rows with broader wells to suppress the well proximity effect, ensuring consistent transistor characteristics across the circuit block.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the space between transistor and well is narrowed to reduce layout area, then block area is reduced, but well proximity effect increases causing transistor characteristic variations
Solution Approach 1:
The patent applies local quality by making the well width variable rather than uniform. Specifically, the well width is set to be larger at end portions of standard cell rows and smaller at central portions. This local variation compensates for the well proximity effect that occurs primarily at end portions where transistors are closer to well edges, thereby maintaining transistor characteristic uniformity across the entire row while minimizing overall area.
Solution Approach 2:
The patent changes the geometric parameter of well width dynamically across different locations. By adjusting the well width parameter based on position (larger at ends, smaller in center), the design optimizes the balance between area efficiency and transistor characteristic consistency, preventing impurity scattering effects at critical end regions.
2Manufacturing precision
If the space between transistor and well is broadened to prevent well proximity effect, then transistor characteristic uniformity is improved, but block area increases
Solution Approach 1:
Instead of uniformly broadening the space between transistors and wells across the entire layout, the patent applies local quality by selectively increasing well width only at end portions where the well proximity effect occurs. The central portions maintain smaller well widths, thus preventing characteristic variations where needed while minimizing area increase.
Solution Approach 2:
The patent applies partial action by implementing the well width adjustment only at specific locations (end portions of standard cell rows) rather than uniformly across all regions. This targeted approach addresses the well proximity effect problem locally without unnecessarily increasing the overall block area.
3Ease of manufacture
If standard cell rows are arranged with flipped orientation to share wells, then manufacturing complexity is reduced, but end portion transistors experience different characteristics due to single-sided well sharing
Solution Approach 1:
The patent maintains the flipped orientation arrangement for well sharing but introduces local quality by adjusting well widths at end portions. This compensation mechanism addresses the asymmetric well-sharing situation at ends while preserving the manufacturing simplicity of the flipped arrangement in the majority of the layout.
Solution Approach 2:
The patent intentionally introduces asymmetry in well width at end portions to compensate for the asymmetric well-sharing arrangement caused by flipped standard cell rows. This controlled asymmetry balances the transistor characteristics at end portions, which would otherwise be degraded by the single-sided well sharing geometry.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces the well proximity effect, eliminating differences in transistor characteristics between end and non-end transistors, thereby improving circuit performance, yield, and reducing block area, enhancing the competitiveness of semiconductor integrated circuits.
Implementation Method 1
a phenomenon called a well proximity effect is more likely to occur. The well proximity effect is a phenomenon such that, when impurities are implanted into a well, the impurities are reflected and scattered from a resist and are then implanted into a channel region of a transistor
Implementation Method 2
when impurities are implanted into a well, the impurities are reflected and scattered from a resist and are then implanted into a channel region of a transistor
Data Source
AI summary
A semiconductor integrated circuit device capable of suppressing variations in transistor characteristics due to the well proximity effect is provided. Standard cell rows are arranged in a vertical direction, each standard cell row including standard cells arranged in a horizontal direction. In the standard cell rows, positions of the N well and the P region in the vertical direction are switched every other row. Adjacent standard cell rows share the P region or the N well. A distance from a PMOS transistor located at an end of a standard cell row to an end of an N well is greater than or equal to a width of an N well shared by standard cell rows.