Alternating Sidewall Spacers for Sub-20 Nm Pitch Patterning
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Solution Overview
Problem
Current methods face challenges in reliably transferring patterns with sub-20 nanometer pitches, particularly below 14 nm, for achieving both 7 nm lines and spaces in integrated circuit fabrication, and struggle with pitch scaling using self-aligned multiple patterning techniques.
Innovation Solution
A method involving the formation of alternating sidewall spacers on a substrate, where mandrels are initially created with a specific pitch and then removed to allow for additional spacer formation, enabling precise control of metal critical dimension and spacing through atomic layer deposition, allowing for sub-20 nm pitch structures using a single mask patterning step and pitch multiplication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If self-aligned multiple patterning techniques are used for pitch scaling, then pattern transfer capability is improved, but manufacturing complexity increases significantly
Solution Approach 1:
The patent segments the pitch multiplication process into distinct stages: first forming mandrels at a relaxed pitch, then forming spacers on mandrel sidewalls, selectively removing mandrels, and forming additional spacers. This segmentation transforms a single complex high-resolution patterning step into multiple simpler steps with lower individual resolution requirements, thereby reducing manufacturing complexity while maintaining pattern transfer capability
Solution Approach 2:
The patent applies preliminary action by first forming mandrels at a larger, more manufacturable pitch before creating the final fine-pitch structures. The mandrels serve as preliminary structures that define the initial pattern, which is then refined through subsequent spacer formation and mandrel removal steps, enabling precise final pitch control without directly patterning at the final sub-20 nm dimensions
2Ease of manufacture
If conventional photolithography is used for direct patterning, then process simplicity is maintained, but achievable pitch is limited above 20 nm
Solution Approach 1:
The patent introduces mandrels as intermediary structures that are not part of the final product but enable the formation of fine-pitch patterns. These mandrels are formed at relaxed dimensions using conventional photolithography, then serve as templates for spacer formation. The mandrels are subsequently removed, having fulfilled their intermediary role of enabling precise pitch multiplication without requiring direct high-resolution patterning
Solution Approach 2:
The patent exploits parameter changes in material properties during the process: using materials with different etch selectivities for mandrels and spacers, and different deposition characteristics for various spacer layers. By changing material parameters and deposition conditions between steps, the process achieves pitch multiplication and fine feature formation using standard lithographic tools, effectively decoupling lithographic resolution from final pattern dimensions
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 enables the creation of sub-20 nm pitch structures with precise control over metal line width and spacing, facilitating efficient back-end-of-line metallization in semiconductor devices by allowing for consistent metal line widths and spacings, and enabling pattern adjustments through spacer thickness and mandrel changes.
Implementation Method 1
Atomic layer deposition can be used as a film formation technique that can deposit one atomic/molecular layer at a time for precise thickness control
Data Source
AI summary
A method of forming a pitch pattern is provided. The method includes forming two adjacent mandrels separated by a first distance, D1, on a substrate, and forming a first set of alternating sidewall spacers between the two adjacent mandrels. The method further includes removing the two adjacent mandrels, and forming a second set of alternating sidewall spacers and a third set of alternating sidewall spacers on opposite sides of the first set of sidewall spacers.