Etch Mask for Sub-Resolution Patterning via Multi-Material Segmentation
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Solution Overview
Problem
Conventional lithographic techniques struggle to create features with critical dimensions less than 20 nm or 10 nm due to poor resolution and rough surfaces, and face challenges in pitch reduction and sub-resolution line connections, which are beyond the capabilities of conventional photolithography systems.
Innovation Solution
The method involves forming a multi-line layer with alternating materials of different etch resistivities on a substrate, creating a patterned etch mask to selectively etch features and create cuts or blocks, allowing for pitch reduction and high-resolution feature creation by using materials with controlled deposition techniques such as atomic layer deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithographic techniques are used, then the process is simple and well-established, but the resolution is insufficient for features less than 20 nm and pitch reduction is limited
Solution Approach 1:
The patterning process is divided into multiple steps: forming mandrels at a first pitch, depositing spacers on mandrel sidewalls, selectively removing mandrels, and repeating the process. This segmentation enables achievement of sub-20nm features and pitch reduction while maintaining process control through distinct, manageable stages rather than attempting single-step patterning
Solution Approach 2:
The patent transitions from planar 2D lithographic patterning to 3D structured patterning by forming vertical spacers on mandrel sidewalls. This dimensional transition enables pitch multiplication and sub-resolution feature creation, as the vertical spacer height provides an additional degree of freedom for controlling final feature dimensions beyond what conventional 2D lithography can achieve
2Manufacturing precision
If pitch reduction techniques are applied to increase feature density, then sub-resolution features can be created, but making cuts or connections between these lines becomes challenging
Solution Approach 1:
The patent applies different materials with distinct etch selectivities to different regions: mandrels made of first material, spacers made of second material, and fill structures made of third material. This local differentiation enables selective etching operations to create cuts and connections at specific locations while preserving other features, solving the challenge of modifying sub-resolution patterns without affecting adjacent structures
Solution Approach 2:
The patent changes material parameters (etch selectivity) to enable subsequent processing steps. By selecting materials with vastly different etch rates and selectivities, the process allows for precise control over which features are removed or modified during etching, enabling cuts and connections to be made through selective removal of specific material layers while leaving others intact
3Manufacturing precision
If conventional photolithography is used, then the process is straightforward, but it cannot provide the uniformity and fidelity desired for very small dimensions
Solution Approach 1:
The patent replaces conventional photolithographic patterning with a deposition-based approach using atomic layer deposition (ALD) for spacer formation. This substitution enables atomic-layer precision and conformal coverage, achieving uniformity and fidelity at sub-20nm dimensions that cannot be obtained through optical lithography, despite increasing process complexity
Solution Approach 2:
The patent performs preliminary actions by forming mandrels and spacers with precise dimensions and material properties before final pattern transfer. The mandrels and spacers are prepared in advance with controlled thicknesses and compositions, enabling subsequent selective removal to produce high-fidelity sub-resolution features with uniform 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 high-resolution features with sub-resolution pitch and precise control over critical dimensions, overcoming the limitations of conventional photolithography by increasing feature density and enabling sub-resolution cuts and connections.
Implementation Method 1
Patterning of the radiation-sensitive material generally involves exposure to actinic radiation through a reticle (and associated optics) onto the radiation-sensitive material using, for example, a photolithography system
Implementation Method 2
This mask layer can comprise multiple sub-layers... at least one of the two or more differing materials are selectively removed resulting in a portion of the underlying layer being uncovered
Implementation Method 3
using materials with controlled deposition techniques such as atomic layer deposition
Data Source
AI summary
Techniques disclosed herein provide a method and fabrication structure for pitch reduction for creating high-resolution features and also for cutting on pitch of sub-resolution features. Techniques include using multiple materials having different etch characteristics to selectively etch features and create cuts or blocks where specified. A pattern of alternating materials is formed on an underlying layer. An etch mask is positioned on the pattern of alternating materials. One or more of the alternating materials can be preferentially removed relative to other materials to uncover a portion of the underlying layer. The etch mask and the remaining lines of alternating material together form a combined etch mask defining sub-resolution features.