Semiconductor Double Patterning Using Buffer Layer to Prevent Bridge Formation
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Solution Overview
Problem
Conventional semiconductor fabrication methods face limitations in forming finer patterns with pitches of 40 nm or less due to bridge and pitting phenomena, leading to reduced pattern fidelity and CD uniformity, especially when using double patterning techniques.
Innovation Solution
A method involving the use of a bi-layer resist process with a buffer layer and capping layer to prevent bridge and pitting phenomena, where a first hard mask layer is formed on a substrate, followed by a second hard mask layer, and multiple etch mask patterns are created with specific pitches, using different etch characteristics materials and thermal treatments to control the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional double patterning technique is used to form finer patterns, then photolithography resolution limit is overcome, but bridge and pitting phenomena occur leading to reduced pattern fidelity
Solution Approach 1:
The patent divides the patterning process into multiple sequential steps using different mask layers (first mask material layer, second mask material layer) and etching processes. This segmentation allows each layer to be optimized for specific functions, preventing bridge and pitting phenomena that occur in conventional single-step patterning.
Solution Approach 2:
The patent introduces a vertical dimension by stacking multiple mask material layers at different heights and depths. The first mask material layer is positioned at a first depth while the second mask material layer is positioned at a second depth, creating a three-dimensional masking structure that prevents harmful interactions between patterns.
2Productivity
If pitch is reduced to form finer patterns, then higher integration is achieved, but photolithography resolution limitation prevents meeting design requirements
Solution Approach 1:
The patent segments the patterning into multiple etching steps with different mask layers, allowing each step to work within the capabilities of conventional photolithography while achieving finer final pitch through the combination of multiple patterns from different layers.
Solution Approach 2:
The patent employs periodic alternation between different mask material layers and etching processes. The first mask material layer forms one set of patterns, then the second mask material layer forms additional patterns, creating a periodic sequence of patterning operations that multiply the effective resolution.
3Manufacturing precision
If distance between second mask material layer pattern and second photoresist pattern is narrowed, then finer pitch is achieved, but bridge formation occurs due to insufficient developer penetration
Solution Approach 1:
The patent resolves the bridge formation problem by moving the second mask material layer to a different vertical depth (second depth) than the first mask material layer (first depth). This vertical separation prevents lateral bridge formation while maintaining the narrow horizontal pitch required for fine patterning.
Solution Approach 2:
The patent performs preliminary positioning of the second mask material layer at a specific depth before the actual patterning operation. This preliminary action of depth control ensures that subsequent etching and development processes can proceed without bridge formation, even at narrow pitches.
4Manufacturing precision
If organic ARC layer is added to increase CD uniformity, then critical dimension control is improved, but bridge formation occurs if ARC is not sufficiently removed
Solution Approach 1:
The patent extracts and eliminates the need for organic ARC layers by using inorganic mask material layers with distinct etch characteristics. This extraction removes the source of bridge formation problems associated with organic ARC while maintaining CD uniformity through the inorganic layer structure.
Solution Approach 2:
The patent uses composite inorganic mask material layers with different etch selectivities (first mask material layer, second mask material layer) to achieve both CD uniformity and prevent bridge formation. The composite structure allows differential etching that maintains precision without the harmful effects of organic materials.
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 prevents pattern failures and enhances pattern fidelity and CD uniformity by overcoming photolithography resolution limits, allowing for the formation of finer patterns with improved precision and reduced defects.
Implementation Method 1
The buffer layer may be anisotropically etched using the second etch mask pattern as an etch mask, forming a buffer layer pattern
Implementation Method 2
The second hard mask layer may be anisotropically etched using the first etch mask pattern and/or the buffer layer pattern as etch masks, forming a second hard mask pattern
Implementation Method 3
The first hard mask layer may be anisotropically etched using the second hard mask pattern as an etch mask, forming a first hard mask pattern
Implementation Method 4
The etched layer may be anisotropically etched using the first hard mask pattern as an etch mask
Data Source
AI summary
Methods of fabricating a semiconductor device are provided. Methods of forming a finer pattern of a semiconductor device using a buffer layer for retarding, or preventing, bridge formation between patterns in the formation of a finer pattern below resolution limits of a photolithography process by double patterning are also provided. A first hard mask layer and/or a second hard mask layer may be formed on a layer of a substrate to be etched. A first etch mask pattern of a first pitch may be formed on the second hard mask layer. After a buffer layer is formed on the overall surface of the substrate, a second etch mask pattern of a second pitch may be formed thereon in a region between the first etch mask pattern. The buffer layer may be anisotropically etched using the second etch mask pattern as an etch mask, forming a buffer layer pattern. The second hard mask layer may be anisotropically etched using the first etch mask pattern and/or the buffer layer pattern as etch masks, forming a second hard mask pattern. The first hard mask layer may be anisotropically etched using the second hard mask pattern as an etch mask, forming a first hard mask pattern. The etched layer may be anisotropically etched using the first hard mask pattern as an etch mask.