Immersion Lithography Drying Section for Resist Pattern Integrity
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Solution Overview
Problem
Conventional immersion lithography in semiconductor fabrication results in defective resist patterns due to water droplets remaining on the resist film after exposure, leading to resist deterioration and poor pattern formation, especially for small feature sizes, which affects the productivity and yield of semiconductor device fabrication.
Innovation Solution
An exposure system and pattern formation method that includes an immersion lithography setup with a drying section to remove and dry the immersion liquid from the resist film surface after exposure, using air blowing, dehumidification, or warming to prevent liquid-induced deterioration, ensuring the resist film is free of residual liquid before development.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If immersion lithography is used to improve resolution, then the resolution of the resist film is improved, but remaining drops of immersion liquid deteriorate the resist and cause defective patterns
Solution Approach 1:
The patent applies preliminary action by introducing a drying section that removes immersion liquid from the resist film surface immediately after exposure, before the liquid can cause deterioration. This preventive measure eliminates the harmful effect of remaining drops while preserving the resolution benefits of immersion lithography.
Solution Approach 2:
The patent extracts the harmful element (immersion liquid drops) from the system by introducing a drying section that removes the liquid from the resist film surface after exposure. This separation eliminates the detrimental interaction between the liquid and resist while maintaining the useful immersion lithography process.
2Ease of manufacture
If immersion liquid remains on the resist film after exposure, then the process is simple, but the resist deteriorates and pattern shape is defective
Solution Approach 1:
The patent merges the exposure process with a drying process by integrating a drying section into the exposure system. This combination allows the system to perform both exposure and liquid removal in sequence, maintaining process simplicity while eliminating the harmful effects of remaining immersion liquid.
Solution Approach 2:
The drying section acts as an intermediary between the exposure process and the development process, removing the harmful immersion liquid drops before they can deteriorate the resist. This intermediary step preserves pattern integrity without significantly complicating the overall manufacturing process.
3Productivity
If post exposure bake is performed with water drops remaining on the resist film, then the baking process is completed, but the resist is more largely deteriorated
Solution Approach 1:
The patent applies preliminary action by removing immersion liquid drops from the resist film surface before the post-exposure bake process. This prevents the drops from causing concentrated heating and resist deterioration during baking, while still allowing the baking process to complete successfully.
Solution Approach 2:
The drying section provides beforehand cushioning by removing harmful liquid drops before the post-exposure bake process, preventing the potential damage that would occur during heating. This protective measure ensures resist quality is maintained throughout the baking 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
The method effectively prevents resist film deterioration and maintains the integrity of the resist pattern shape, enhancing the resolution and yield of semiconductor device fabrication by ensuring complete removal of immersion liquid, thereby improving the quality of the resist pattern formed.
Implementation Method 1
a region in an exposure system sandwiched between a projection lens and a resist film formed on a wafer is filled with a liquid having a refractive index n (whereas n>1) and therefore, the NA (numerical aperture) of the exposure system has a value n·NA
Implementation Method 2
An exposure system and pattern formation method that includes an immersion lithography setup with a drying section to remove and dry the immersion liquid from the resist film surface after exposure, using air blowing, dehumidification, or warming to prevent liquid-induced deterioration
Data Source
AI summary
An exposure system includes an exposure section provided within a chamber for irradiating a resist film formed on a wafer with exposing light through a mask with an immersion liquid provided on the resist film. It further includes a drying section for drying the surface of the resist film after the irradiation.