Semiconductor Device Layout with Dual-Density Dummy Regions
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Solution Overview
Problem
In semiconductor manufacturing, the density-gradient effect leads to significant current mismatch between transistors in a metal-oxide-semiconductor transistor array, particularly due to edge-to-center current mismatch, which existing approaches struggle to fully address despite improving standard deviation, leaving mean shift unresolved.
Innovation Solution
Surrounding the cell array with a first region and a second region, where the first region has a higher pattern density and the second region has a lower pattern density, allowing for optimal adjustment of their widths to alleviate current mismatch by reducing edge-to-center current mean shift and standard deviation, while minimizing area penalty.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single dummy region surrounds the cell array, then area penalty is reduced, but current mismatch (mean shift) cannot be sufficiently alleviated
Solution Approach 1:
The dummy region is segmented into two distinct regions: a first dummy region with first density and a second dummy region with second density. This segmentation allows each region to serve different purposes in mitigating the density-gradient effect, with the first region providing primary compensation and the second region providing additional refinement, thereby reducing current mismatch more effectively than a single uniform dummy region while maintaining area efficiency.
Solution Approach 2:
Different dummy regions are assigned different pattern densities tailored to their specific locations and functions. The first dummy region has a first density optimized for its position, while the second dummy region has a second density optimized for its position and the specific mismatch issues it addresses. This local optimization of density allows for more precise control of current distribution without requiring excessive area.
2Area of stationary object
If existing dummy region approaches are used, then area penalty is minimized, but edge-to-center current mean shift remains unresolved
Solution Approach 1:
The dummy region is divided into multiple segments with different densities - a first dummy region with first density and a second dummy region with second density. This segmentation enables targeted compensation for edge-to-center current variations, with each segment addressing specific spatial variations in the cell array, thereby improving manufacturing precision without increasing area penalty.
Solution Approach 2:
The invention changes the density parameter of dummy regions from uniform to non-uniform, with at least two different density values used in different spatial locations. This parameter variation allows the dummy regions to more accurately compensate for the spatially varying density-gradient effect, improving edge-to-center current matching precision without requiring larger area.
3Productivity
If transistor density is increased for smaller feature sizes, then device functionality is improved, but density-gradient effect and current mismatch become more severe
Solution Approach 1:
The dummy regions are designed with locally optimized densities that correspond to the specific density requirements of different areas of the cell array. By placing dummy regions with appropriate densities adjacent to the cell array, the invention locally compensates for the density-gradient effect caused by high transistor density, thereby maintaining current matching reliability without reducing device functionality.
Solution Approach 2:
The invention uses a composite structure of dummy regions with different densities surrounding the cell array. This composite approach combines multiple density levels to create a graduated transition zone that mitigates the abrupt density changes caused by high-density transistor packaging, thereby reducing current mismatch while preserving the benefits of high device density.
Data Source
AI summary
In some embodiments, a semiconductor device includes a cell array, a first region and a second region. The first region surrounds the cell array and has a first pattern density. The second region is between the cell array and the first region. The second region surrounds the cell array and has a second pattern density smaller than a third pattern density of the cell array, which in turn is smaller than the first pattern density.