Combined Etch Mask for Sub-Resolution Patterning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional lithographic techniques struggle to achieve high-resolution features with critical dimensions below 20 nm due to poor resolution and rough surfaces, and challenges in pitch reduction and sub-resolution line connections.
Innovation Solution
A method involving the formation of a patterned hardmask layer with multiple materials of differing etch characteristics, allowing for selective etching and creation of sub-resolution features, including the use of a multi-line layer with alternating lines of varying materials to form a combined etch mask for precise pattern transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithographic techniques are used, then manufacturing process is simple, but manufacturing precision deteriorates for features below 20 nm
Solution Approach 1:
The patterning process is divided into multiple discrete steps: forming mandrels at a first pitch, depositing spacers conformally on mandrels, selectively removing alternating mandrels and spacers, and repeating the process. This segmentation enables achievement of sub-20nm features through sequential operations rather than a single complex lithography step.
Solution Approach 2:
The patent transitions from two-dimensional planar patterning to three-dimensional vertical structures by forming conformal spacer layers around mandrels. This dimensional transition enables pitch multiplication where the final feature pitch is multiples of the original mandrel pitch, achieving sub-resolution features beyond optical limits.
2Manufacturing precision
If pitch reduction techniques are applied, then feature density increases, but surface roughness increases
Solution Approach 1:
Conformal spacer deposition is a self-aligned process where the spacer thickness is determined by the deposition process itself rather than lithographic patterning. This self-service mechanism ensures uniform spacer thickness and smooth surfaces, as the deposition automatically conforms to the mandrel geometry without requiring additional alignment steps.
3Manufacturing precision
If conventional photo-lithography is used, then process is straightforward, but pitch reduction capability is limited
Solution Approach 1:
Mandrels are formed in advance at a relaxed pitch that is within the capabilities of conventional lithography systems. These pre-formed mandrels serve as templates for subsequent spacer deposition, enabling final feature pitches smaller than the original lithographic resolution limit through the preliminary structuring step.
Solution Approach 2:
The patent changes the critical dimension control parameter from lithographic exposure parameters to deposition thickness parameters. By controlling spacer thickness through atomic layer deposition or chemical vapor deposition, the final feature dimensions are determined by film thickness rather than optical resolution, enabling sub-20nm precision.
4Manufacturing precision
If sub-resolution lines are created, then pattern density increases, but ability to make cuts or connections deteriorates
Solution Approach 1:
Specific materials are selectively removed from the multi-layer structure to create openings, cuts, or connections. By selectively etching away certain mandrels or spacers while preserving others, the patent enables local modifications to the pattern for electrical connections or device features while maintaining high overall pattern density from the self-aligned spacer structure.
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
Enables high-resolution feature creation and pitch reduction, overcoming the limitations of conventional photolithography by achieving sub-resolution features and precise pattern transfer, even below the capabilities of existing photolithography systems.
Implementation Method 1
Each line of the pattern of alternating lines is uncovered on a top surface of the multi-line layer and vertically extends to a bottom surface of the multi-line layer. At least two of the two or more differing materials differ chemically from each other by having different etch resistivities relative to each other. At least one of the two or more differing materials are selectively removed resulting in a portion of the patterned hardmask layer being uncovered.
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 hardmask is positioned first on an underlying layer or layers to be etched. A pattern of alternating materials is formed on the hardmask. One or more of the alternating materials can be preferentially removed relative to other materials to uncover a portion of the hardmask layer. The hardmask and the remaining lines of alternating material together form a combined etch mask defining sub-resolution features.