Multi-Layer Resist Patterning for Low-LER EUV Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenges in forming fine patterns for semiconductor devices include line edge roughness (LER) and uniformity issues due to the use of chemically amplified resists (CARs) in extreme ultraviolet (EUV) lithography, leading to resist blur and insufficient etch selectivity.
Innovation Solution
A method involving the formation of a resist structure with multiple layers, including a first resist pattern and subsequent layers formed through deposition processes, followed by dry developing techniques, to create a uniform critical dimension and shape, using non-chemically amplified resist materials like metal oxides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemically amplified resists (CARs) are used in EUV lithography, then fine patterns can be formed, but line edge roughness (LER) increases and uniformity deteriorates
Solution Approach 1:
The patent divides the single resist layer into multiple resist layers (first resist layer, second resist layer, and optionally third resist layer) with different materials and functions. Each layer serves a specific purpose: the first layer provides pattern definition, the second layer suppresses LER, and the third layer enhances etch selectivity. This segmentation resolves the contradiction by distributing different functions across multiple layers rather than relying on a single CAR layer that compromises both pattern formation and edge quality.
Solution Approach 2:
The patent employs composite resist structures combining different material types (non-CAR materials like metal oxides in the first resist layer, and CAR materials in subsequent layers). This composite approach allows each material to contribute its strengths: non-CAR materials provide sharp edges and low LER, while CAR materials enable fine pattern formation through chemical amplification. The combination resolves the contradiction by integrating complementary properties of different material systems.
2Manufacturing precision
If chemically amplified resists (CARs) are used in EUV lithography, then fine patterns can be formed, but resist blur increases and uniformity decreases
Solution Approach 1:
The patent segments the resist system into multiple layers where the first resist layer uses non-CAR materials (metal oxides) that do not suffer from chemical amplification-induced blur. This first layer provides a stable, uniform foundation with sharp boundaries. Subsequent CAR layers are deposited on top, and through selective removal processes, the uniformity of the first layer is preserved while the fine patterning capability of CARs is utilized in upper layers.
Solution Approach 2:
The patent applies different material qualities to different regions/layers of the resist structure. The first resist layer (closest to the substrate) uses non-CAR materials with high uniformity and stability, while upper layers use CAR materials optimized for pattern definition. This local differentiation of material properties resolves the contradiction by placing each material type where its specific advantages are most needed.
3Manufacturing precision
If chemically amplified resists (CARs) are used in EUV lithography, then fine patterns can be formed, but etch selectivity becomes insufficient
Solution Approach 1:
The patent introduces a dedicated third resist layer (in some embodiments) or utilizes the first resist layer as an etch mask with superior etch selectivity. The non-CAR material in the first layer provides excellent etch resistance and selectivity against the underlying layers, while the CAR-based pattern definition is maintained in upper layers. This segmentation allows independent optimization of pattern definition and etch selectivity functions.
Solution Approach 2:
The first resist layer made of non-CAR materials serves as an intermediary between the substrate and the CAR-based pattern layers. It provides a stable interface with high etch selectivity, protecting the underlying structure during etching processes while allowing the CAR layers above to define fine patterns. This intermediary layer resolves the contradiction by decoupling the etch selectivity function from the pattern definition function.
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 the precision and accuracy of the patterning process, improving the uniformity and reducing line edge roughness, resulting in more uniform and precise semiconductor device features.
Implementation Method 1
forming a second resist layer covering a side wall and a top surface of the first resist pattern and extending on a top surface of the under layer by performing a deposition process on the first resist pattern
Data Source
AI summary
A method of forming a pattern includes forming an etching target layer on a substrate, forming an under layer on the etching target layer, forming a first resist pattern on the under layer, forming a second resist layer covering a side wall and a top surface of the first resist pattern and extending on a top surface of the under layer, forming a second resist pattern covering the side wall of the first resist pattern by removing a portion of the second resist layer on the top surface of the under layer, and performing an etching process using a resist structure as an etch mask, where the resist structure includes the first resist pattern and the second resist pattern.