Dummy Cell Array for FinFET Process Uniformity
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Solution Overview
Problem
The high integration of semiconductor devices leads to time-consuming and expensive layout design in semiconductor integrated circuits, particularly due to the need for uniform process conditions across the entire wafer or substrate, which existing technologies struggle to achieve efficiently.
Innovation Solution
A dummy cell array structure is introduced, comprising a plurality of dummy unit cells arranged around the device area, with each dummy unit cell having a structure corresponding to a device unit cell, including active areas and gate lines that extend beyond the cell boundary, allowing for uniform semiconductor processes and improved uniformity and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high integration of semiconductor devices is implemented, then device density and functionality are improved, but layout design time and cost increase significantly
Solution Approach 1:
The semiconductor substrate is divided into a device area and a dummy cell array area, with the dummy cell array further segmented into multiple dummy unit cells arranged in a grid pattern. This segmentation allows the dummy structures to be systematically distributed around the device area, providing uniform process conditions without requiring complex custom layout design for each region.
Solution Approach 2:
The dummy unit cells are designed with specific structural parameters including active areas extending beyond cell boundaries in the first direction and gate lines extending beyond cell boundaries in the second direction. These parameter changes create uniform process conditions across the substrate, enabling consistent manufacturing while simplifying the overall layout design process through standardized repeating units.
2Manufacturing precision
If uniform process conditions are maintained across the entire wafer, then manufacturing precision is improved, but device area available for functional circuits is reduced
Solution Approach 1:
The dummy cell array acts as an intermediary region between different functional device areas. By placing dummy unit cells with extending active areas and gate lines around the device area, the dummy structures serve as buffer zones that maintain uniform process conditions (such as CMP planarity and thermal distribution) without directly interfering with the functional devices, thus achieving process uniformity while preserving functional device performance.
Solution Approach 2:
The dummy unit cells utilize spatial extension beyond cell boundaries in perpendicular directions (active areas extending in the first direction, gate lines extending in the second direction) to create uniform process conditions. This dimensional approach allows the dummy structures to influence process uniformity across the wafer without occupying excessive functional device area, as the extending structures work in the dimensional space surrounding the core functional regions.
3Manufacturing precision
If dummy structures with extending active areas and gate lines are used, then process uniformity is improved, but structural complexity increases
Solution Approach 1:
The dummy unit cells are designed as universal repeating structures that serve multiple functions: providing CMP planarity, maintaining thermal uniformity, defining process boundaries, and enabling consistent patterning across the wafer. Each dummy unit cell with its extending active area and gate line configuration acts as a multi-functional element that addresses various process uniformity requirements simultaneously, reducing the need for multiple different dummy structure types and simplifying the overall manufacturing process.
Data Source
AI summary
A semiconductor device includes a substrate; a device area of the substrate, the device area including a plurality of device unit cells; and a dummy cell array arranged around the device area. The dummy cell array includes a plurality of dummy unit cells repeatedly arranged in a first direction and a second direction perpendicular to the first direction, each of the dummy cell unit having a structure corresponding to a device unit cell. The device unit cell includes at least a first transistor in the device area. The structure of the dummy unit cell includes an active area and a gate line. For each dummy unit cell, the active area and the gate line extend beyond a cell boundary that defines the dummy unit cell.