VUV Curing for DSA Block Copolymer Defect Metrology
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Solution Overview
Problem
Current photolithography techniques and Directed Self Assembly (DSA) methods face challenges in achieving sub-25 nm feature sizes and suffer from pattern defectivity, such as line edge roughness and line width roughness, due to the organic nature of block copolymers like polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA), which are difficult to etch selectively, and traditional metrology methods struggle to detect sub-surface and bulk defects.
Innovation Solution
A method involving a vacuum ultra-violet (VUV) curing process to enhance etch resistance and defect visibility, followed by a dry plasma etch process, allowing for defect metrology and pattern formation with improved selectivity and reduced processing steps, enabling the detection and mitigation of defects like bridging and sidewall roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional etching techniques are used on block copolymers, then the organic materials can be removed, but etch selectivity is poor and pattern defectivity increases
Solution Approach 1:
The patent applies a preliminary oxygen plasma treatment to the block copolymer surface before the main etching process. This pre-treatment modifies the surface chemistry to enhance etch selectivity and reduce pattern defectivity by creating a more uniform and reactive surface that responds better to subsequent etching steps
Solution Approach 2:
The patent modifies etching parameters including plasma power, pressure, and gas composition to optimize the etching process. By adjusting these parameters, the process achieves better etch selectivity while minimizing pattern defectivity such as line edge roughness and line width roughness
2Measurement precision
If traditional metrology methods are used, then the process is simple, but sub-surface and bulk defects cannot be detected
Solution Approach 1:
The patent introduces an intermediary layer or contrast-enhancing material that allows traditional metrology methods to indirectly detect sub-surface and bulk defects. This intermediary acts as a mediator that translates internal defect information into visible surface features that can be detected by conventional inspection tools
Solution Approach 2:
The patent employs optical contrast enhancement techniques where defects are made visible through changes in optical properties such as reflectivity, absorption, or interference patterns. This allows sub-surface defects to be detected through surface optical signatures without requiring complex imaging equipment
3Length of moving object
If photolithography is used to reduce feature sizes, then manufacturing capability is maintained, but feature sizes are limited to about 25 nm
Solution Approach 1:
The patent utilizes directed self-assembly of block copolymers where the material automatically organizes into desired nanoscale patterns through thermodynamic self-organization. This self-service mechanism enables feature sizes below 25 nm to be achieved without requiring proportionally more complex lithography equipment, maintaining manufacturing feasibility while breaking the resolution barrier
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 enhances defect detection and pattern quality, reduces manufacturing time and cost, and allows for more precise control of integration variables, making DSA devices manufacturable and cost-effective for advanced technology nodes.
Implementation Method 1
performing a vacuum ultra-violet (VUV) curing process on the substrate to enhance etch resistance of the second material during a subsequent etch process and to enable metrology to detect defects underneath a surface of the top layer
Implementation Method 2
performing an etch process to remove the second material using a dry plasma process
Data Source
AI summary
The described embodiments include performing a curing process for selective treatment, or hardening, of PS regions in PS-b-PMMA block copolymer DSA films prior to dry etch development of PMMA regions. In various embodiments, the curing chemistry can be Ar/H2, HBr, N2/H2, etc., which has the capability of generating Vacuum Ultraviolet (VUV) photon flux for polymer curing. The curing effect may enhance the etch resistance of PS regions, thereby freezing the bulk defects during plasma PMMA removal. The defects can then be measured by commonly used metrology techniques like CDSEM and quantized.