Grafting Polymer Spacer Patterning for Sub-Resolution Trenches
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Solution Overview
Problem
Conventional lithographic techniques face limitations in feature size and pitch resolution, necessitating complex and costly self-aligned multiple patterning schemes for creating small trench, contact hole, and slot contact structures in integrated circuit fabrication.
Innovation Solution
The use of a grafting polymer material with little or no etch resistance for creating a deposited spacer that selectively adheres to mandrels without adhering to the underlying layer, allowing for fast and selective etching, and incorporation in an anti-spacer flow to pattern sub-resolution trenches and contact structures with improved control over critical dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithographic techniques are used for patterning, then the process is simple and direct, but the feature size and pitch resolution are limited
Solution Approach 1:
The patterning process is divided into multiple sequential steps: forming mandrels, depositing spacers, removing mandrels, and forming final patterns. This segmentation allows each step to be optimized independently, achieving sub-lithographic resolution through the combination of multiple simpler operations rather than requiring a single high-resolution lithography step
Solution Approach 2:
Mandrels are introduced as intermediary structures that serve as templates for spacer formation. These mandrels are not part of the final device but enable the creation of smaller features by providing a larger initial structure that can be precisely replicated at reduced dimensions through the spacer deposition process
2Manufacturing precision
If self-aligned multiple patterning schemes are used to create small structures, then feature resolution is improved, but processing complexity and cost increase
Solution Approach 1:
Multiple patterning operations are merged into a single integrated process flow where spacers are deposited conformally on mandrels and then the mandrels are removed, leaving precisely defined patterns without requiring separate alignment steps. This combining of operations maintains high precision while reducing process complexity
Solution Approach 2:
The spacer material self-aligns to the mandrel structures through conformal deposition, automatically defining the final pattern position and dimension without requiring additional alignment operations. The process is self-aligned by nature of the deposition geometry, eliminating the need for complex alignment procedures
3Ease of manufacture
If conventional photoresist materials are used, then the material is readily available and easy to process, but etch resistance is limited
Solution Approach 1:
The patent employs composite material structures where spacers are formed from materials with specific etch resistance properties that differ from both the mandrel and filler materials. This composite approach allows the spacer to serve as a protective mask during selective etching operations, providing the necessary etch resistance while maintaining processability
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 reduces processing complexity and cost, while achieving improved edge placement accuracy, line-edge roughness, and critical dimension uniformity compared to conventional EUV exposure and SAMP processes, enabling the creation of features smaller than conventional photolithographic resolution.
Implementation Method 1
The spacer material selectively adheres to exposed surfaces of the mandrels without adhering to exposed surfaces of the target layer
Implementation Method 2
This material can be used to create a deposited spacer with fast and selective etching
Data Source
AI summary
Patterning methods for creating sub-resolution trenches, contact openings, lines, and other structures at smaller dimensions as compared to using conventional self-aligned multiple patterning and sequential litho-etch deposition patterning approaches. Techniques herein include patterning using a grafting polymer material that has been modified to provide little or no etch resistance (fast etching). The grafting polymer material is deposited as spacer material on a substrate having mandrels. The spacer material selectively adheres to mandrel surfaces without adhering to exposed portions of an underlying layer. The spacer material also adheres up to a specific length so that sidewall spacers are formed. Openings between spacers are filled with a filler material, and then the sidewall spacers, made of the grafting material, are etched thereby creating antispacers. Etch transfer to a memorization layer and/or using additional relief patterns can be incorporated for creating various features.