Modifying Layer for Reducing Line Edge Roughness in Photolithography
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Solution Overview
Problem
Conventional photolithography processes struggle to control line edge roughness (LER) and line width roughness (LWR) in semiconductor fabrication, leading to poor device performance and yield, particularly as critical dimensions shrink, due to limitations in photoresist chemical properties, wavelength, and optical system resolution.
Innovation Solution
A method involving the deposition of a modifying layer on a substrate, followed by a photoresist layer, where the modifying layer is etched and treated to reduce LER and LWR, allowing for a finer pattern with increased photolithography resolution through molecular reorganization and alignment using techniques like ultraviolet radiation or heat above the glass transition temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography process is used, then manufacturing process is simple, but line edge roughness and line width roughness increase leading to poor device performance
Solution Approach 1:
The patent divides the photolithography process into multiple sequential steps: forming a first pattern, performing a treatment to reduce roughness, and forming a second pattern. This segmentation allows each step to be optimized independently, with the treatment step specifically targeting LER/LWR reduction without compromising the overall manufacturing capability.
Solution Approach 2:
The treatment is performed on the etched modifying layer before the final pattern transfer to the substrate. This preliminary action reduces LER and LWR in advance, ensuring that the subsequent etching process produces high-quality patterns with minimal roughness, thereby improving device performance before the final structure is formed.
2Length of moving object
If critical dimension is reduced for miniaturization, then device density increases, but control of line edge roughness and line width roughness becomes more difficult
Solution Approach 1:
The patent applies a treatment that changes the physical or chemical parameters of the modifying layer to reduce LER and LWR. By adjusting parameters such as molecular alignment, density, or surface properties through the treatment step, the roughness is reduced even as critical dimensions are reduced, enabling continued miniaturization with maintained precision.
3Measurement precision
If photoresist chemical properties and optical system limits are reached, then further resolution improvement becomes difficult, but device performance requires better resolution
Solution Approach 1:
The patent introduces a modifying layer as an intermediary between the photoresist and the substrate. This modifying layer undergoes a treatment that reduces LER and LWR, acting as a mediator that improves the final pattern quality without requiring changes to the photoresist chemistry or optical system. The modifying layer absorbs the roughness reduction function, allowing the existing photoresist and optical systems to continue operating at their limits.
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 photolithography resolution, reduces image blurring, and enables further miniaturization of microelectronic devices by minimizing line edge and width roughness, thereby improving semiconductor device performance and yield.
Implementation Method 1
molecular reorganization and alignment using techniques like ultraviolet radiation
Implementation Method 2
heat above the glass transition temperature
Data Source
AI summary
A method of forming a fine pattern comprises depositing a modifying layer on a substrate. A photoresist layer is deposited on the modifying layer, the photoresist layer having a first pattern. The modifying layer is etched according to the first pattern of the photoresist layer. A treatment is performed to the etched modifying layer to form a second pattern, the second pattern having a smaller line width roughness (LWR) and/or line edge roughness (LER) than the first pattern. The second pattern is then etched into the substrate.