Dummy Structures for Strain Stress Control in IC Edge Regions
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Solution Overview
Problem
The scaling down of semiconductor integrated circuits leads to increased power dissipation and performance variations due to strained transistor channels and stress effects in edge regions without dummy patterns, causing operational current deviations and manufacturing challenges.
Innovation Solution
Incorporating dummy structures, such as OD and gate dummy patterns, adjacent to the edge regions of the core area to confine transistor channels and control strain stress, thereby reducing process loading and stress-induced performance variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the geometry size is decreased to increase functional density, then production efficiency is improved and costs are lowered, but power dissipation increases and transistor performance variations occur due to strain stress effects
Solution Approach 1:
The patent applies local quality by introducing dummy transistor patterns specifically at edge regions where performance variations occur, while leaving central regions unchanged. This localized modification addresses the strain stress problem at boundaries without affecting the overall circuit design, thereby maintaining production efficiency while improving transistor performance consistency at edge locations.
Solution Approach 2:
The dummy transistor patterns are formed in advance during the manufacturing process, before the actual edge region transistors are activated. This preliminary action of creating dummy structures beforehand establishes a controlled strain stress environment that prevents performance variations in the functional edge transistors, resolving the contradiction between scaling benefits and performance consistency.
2Reliability
If dummy structures are added to edge regions to control strain stress, then transistor performance consistency is improved, but device complexity and manufacturing process complexity increase
Solution Approach 1:
The patent uses copying by creating dummy transistor patterns that replicate the structure and dimensions of functional transistors. These copied dummy structures are placed at edge regions to simulate the strain stress conditions of functional devices, thereby controlling performance variations without requiring new or complex structural designs. This approach improves operational current consistency while minimizing increases in device complexity.
Solution Approach 2:
The dummy transistor patterns are designed with specific dimensional parameters (width, length, spacing) that are optimized to control strain stress effects. By carefully selecting these parameters, the patent achieves improved transistor performance consistency without unnecessarily complicating the device structure. The parameter optimization ensures that the dummy structures provide the necessary strain control while maintaining manufacturing feasibility.
3Manufacturing precision
If dummy patterns are disposed at boundary regions to reduce process loading effects, then manufacturing precision is improved, but ease of manufacture decreases due to additional process steps
Solution Approach 1:
The patent merges the formation of dummy transistor patterns with existing manufacturing processes by integrating them into the standard photolithography and etching sequences. The dummy structures are formed using the same process steps as functional transistors, combining multiple functions into a unified manufacturing flow. This approach improves manufacturing precision for edge region transistors while minimizing the impact on process simplicity, as the additional structures are created during routine manufacturing operations.
Data Source
AI summary
An integrated circuit includes a core area. The core area has at least one edge region and a plurality of transistors disposed in the edge region. A plurality of dummy structures are disposed outside the core area and adjacent to the at least one edge region. Each channel of the transistors in a channel width direction faces at least one of the dummy structures.