Mask Forming Method for EUV Lithography
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Solution Overview
Problem
The existing mask forming methods for semiconductor devices face challenges in achieving high accuracy due to defects caused by catalytic reactions and uneven pattern formation, particularly in fine patterns, where Line Edge Roughness (LER) increases and scum is generated during the development process.
Innovation Solution
A mask forming method involving the formation of a photosensitive organic film, selective exposure, post-exposure baking, and exposure to a basic gas or water vapor to create a water-soluble region, allowing for precise removal of the exposed area using a developer, thereby reducing LER and scum formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional mask forming methods are used for fine patterns, then pattern transfer is performed, but Line Edge Roughness increases and scum is generated due to catalytic reactions and uneven pattern formation
Solution Approach 1:
The patent applies preliminary action by performing a base coat treatment before the main photoresist coating. The base coat layer is formed with specific properties (different solubility and etch resistance) to prepare the substrate in advance, preventing defects during subsequent processing steps and ensuring uniform pattern formation from the outset.
Solution Approach 2:
The patent implements local quality by creating distinct layers with different properties: the base coat layer has different solubility and etch resistance characteristics compared to the main photoresist layer. This local differentiation allows each layer to perform its specific function optimally, with the base coat preventing substrate interactions and the main layer providing the patterning function.
2Device complexity
If conventional single-layer photoresist is used, then processing is simplified, but catalytic reactions cause surface defects and uneven pattern formation
Solution Approach 1:
The patent applies segmentation by dividing the photoresist system into two distinct layers: a base coat layer and a main photoresist layer. Each layer has specific compositional and functional characteristics, allowing them to perform separate functions that together prevent catalytic reactions and ensure uniform pattern formation, thereby resolving the contradiction between simplicity and precision.
3Productivity
If fine patterns are formed, then integration is increased, but accuracy requirements increase and defects from catalytic reactions become more significant
Solution Approach 1:
The base coat layer is formed in advance with properties specifically designed to prevent catalytic reactions and ensure uniformity. This preliminary preparation is crucial for fine patterns where even minor defects are magnified, allowing high integration to be achieved while maintaining the required accuracy standards.
Solution Approach 2:
The differentiated properties of the base coat layer (different solubility and etch resistance) provide localized protection and control that is particularly important for fine patterns. This local quality enhancement ensures that the critical dimensions and uniformity required for high integration are maintained throughout the patterning process.
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 method enhances the accuracy of pattern transfer by minimizing unevenness and scum formation, especially in fine patterns, and is particularly effective for EUV exposure light, resulting in improved line-and-space patterns with reduced roughness.
Implementation Method 1
forming a salt in the first region by causing a basic substance to permeate into the first region
Implementation Method 2
generating a first region and a second region in the photosensitive organic film by performing a selective exposure and a post-exposure baking on the photosensitive organic film, the first region having an acidic functional group
Implementation Method 3
performing a selective exposure and a post-exposure baking on the photosensitive organic film
Implementation Method 4
removing the first region by dissolving the salt in a developer
Data Source
AI summary
There is provided a mask forming method, including: forming a photosensitive organic film on a workpiece; generating a first region and a second region in the photosensitive organic film by performing a selective exposure and a post-exposure baking on the photosensitive organic film, the first region having an acidic functional group in the photosensitive organic film, and the second region having a protective group in which the acidic functional group is protected; forming a salt in the first region by causing a basic substance to permeate into the first region using a substance staying in a gaseous state or a solid state; and removing the first region by dissolving the salt in a developer.