Dummy Fin Structure Formation for Semiconductor Device Reliability
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Solution Overview
Problem
The semiconductor industry faces challenges in forming reliable semiconductor devices at smaller sizes due to increased complexity and difficulty in fabrication processes as feature sizes decrease, leading to issues like misalignment and loading effects during etching processes.
Innovation Solution
A method involving multiple etching processes with different etching rates and selectivities is used to form partially removed fin structures, which are then embedded in an isolation feature to prevent short circuits and improve uniformity, addressing misalignment and loading effects by fine-tuning etching conditions and using fin structures as etch stop layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency increases and costs decrease, but fabrication process complexity and difficulty increase
Solution Approach 1:
The patent divides the etching process into multiple stages with different etching conditions. A first etching process forms initial fin structures, followed by a second etching process that selectively removes portions of dummy fin structures. This segmentation allows each etching step to be optimized independently, managing the complexity of fabricating smaller features while maintaining high functional density.
Solution Approach 2:
The patent employs different etching parameters for different regions of the substrate. By adjusting etching selectivity and etching rates between the first and second etching processes, the method achieves precise control over fin structure formation. This parameter optimization enables reliable fabrication at smaller sizes without proportionally increasing process complexity.
2Manufacturing precision
If multiple etching processes are used to form uniform fin structures, then manufacturing precision improves, but process complexity increases
Solution Approach 1:
The patent applies different etching selectivities to different regions: a first etching selectivity for the initial fin formation and a second etching selectivity for the selective removal of dummy fin structures. This local quality approach ensures that each region receives the appropriate etching treatment, achieving uniform fin structures across the substrate while managing process complexity through targeted optimizations.
Solution Approach 2:
The first etching process performs preliminary formation of fin structures with controlled heights and uniformity. This preliminary action creates a foundation that facilitates the subsequent selective removal of dummy fins, allowing the second etching process to focus only on fine-tuning rather than complete formation, thereby improving overall precision without proportionally increasing complexity.
3Reliability
If dummy fin structures are partially removed to prevent short circuits, then device reliability improves, but additional processing steps are required
Solution Approach 1:
The patent extracts or removes portions of dummy fin structures through the second etching process. By selectively removing these dummy fins that would otherwise cause short circuits, the method improves device reliability. The extraction is performed using etching conditions optimized for this specific purpose, integrating the reliability improvement into the existing fabrication flow with minimal additional complexity.
Solution Approach 2:
The dummy fin structures serve as intermediaries during the fabrication process. They are initially formed to maintain pattern uniformity during etching, then selectively removed in a controlled manner. This intermediary role allows the process to achieve both uniform fin formation and short circuit prevention, with the intermediary elements being temporary and purposefully removed after serving their function.
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 enhances the performance and reliability of semiconductor devices by ensuring uniform height and reduced defects, preventing short circuits and improving the uniformity of fin structures within the isolation feature.
Implementation Method 1
removing a portion of the mask layer and a top portion of the dummy fin structure by a first etching operation to form an etched mask layer
Data Source
AI summary
Structures and formation methods of a semiconductor device structure are provided. The method includes forming a dummy fin structure, and forming a mask layer covering the dummy fin structure. The method also includes removing a portion of the mask layer and a top portion of the dummy fin structure by a first etching operation to form an etched mask layer, wherein the dummy fin structure has a protruding portion protruding from a top surface of the etched mask layer after the first etching operation.