Exposure Apparatus Gas Control for Color Filter Precision
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Solution Overview
Problem
Current methods for manufacturing color filters using photosensitive acrylic polymers face challenges with pattern precision due to oxygen absorption by pigment components, leading to alignment and focus errors, especially when using inert gases for low-oxygen exposure, which can disrupt refractive index detection and require additional costly processes like oxygen barrier films.
Innovation Solution
An exposure apparatus with a gas supply unit that maintains a controlled air or mixed gas atmosphere between the projection optical system and substrate, allowing for precise oxygen concentration adjustment and detection of alignment marks, reducing alignment and focus errors by switching between air and mixed gas environments based on exposure requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxygen barrier film made of polyvinyl alcohol is provided on the resist, then oxygen is blocked and polymerization can proceed, but the film has poor wettability on the resist and requires additional coating processes increasing cost
Solution Approach 1:
The invention extracts the oxygen barrier function from a separate physical film layer and integrates it into the resist composition itself by incorporating oxygen-scavenging pigments (such as metal oxides like zinc oxide, titanium oxide, or organic pigments with oxygen trapping capability). This eliminates the need for a separate polyvinyl alcohol oxygen barrier film coating process while maintaining the oxygen-blocking function necessary for successful polymerization.
Solution Approach 2:
The invention merges multiple functions into the resist composition: the base resist polymer provides the photosensitive properties, while incorporated oxygen-scavenging pigments provide the oxygen barrier function. This combination eliminates the need for separate oxygen barrier film application steps, reducing process complexity while ensuring reliable polymerization under exposure light.
2Reliability
If a polyvinyl alcohol oxygen barrier film is coated on the resist, then oxygen is blocked, but the manufacturing cost increases due to additional process steps
Solution Approach 1:
The invention merges the oxygen barrier function with the resist composition by incorporating oxygen-scavenging pigments directly into the resist formulation. This integration eliminates the need for separate oxygen barrier film coating processes, thereby reducing manufacturing costs while maintaining reliable polymerization reactions.
Solution Approach 2:
The invention extracts the oxygen barrier function from a separate expensive polyvinyl alcohol film process and implements it through more cost-effective pigment additives within the resist composition itself, such as metal oxides (zinc oxide, titanium oxide) or organic pigments that can scavenge oxygen at lower material and processing costs.
3Use of energy by moving object
If inert gas is blown onto the resist to maintain low oxygen concentration, then exposure dose is decreased, but alignment mark detection precision deteriorates due to refractive index changes
Solution Approach 1:
The invention extracts the oxygen barrier function from an external inert gas environment (which causes refractive index issues) and implements it through oxygen-scavenging pigments incorporated directly into the resist composition. This allows exposure to proceed in a normal atmosphere without inert gas interference, maintaining both low effective oxygen concentration at the resist interface and accurate alignment mark detection through unchanged refractive index conditions.
4Reliability
If higher energy exposure light is used to overcome pigment absorption, then polymerization can proceed despite oxygen presence, but pattern precision deteriorates due to increased oxygen trapping effects
Solution Approach 1:
The invention converts the harmful oxygen-trapping effect into a beneficial localized oxygen-scavenging mechanism by incorporating oxygen-scavenging pigments throughout the resist composition. These pigments actively consume oxygen in their vicinity, creating oxygen-depleted zones that facilitate polymerization without requiring excessive exposure energy, thereby maintaining pattern precision while ensuring reliable reaction completion.
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 apparatus achieves precise target pattern shapes and line widths by minimizing alignment and focus errors through controlled gas environments, enhancing pattern precision and reducing the need for additional processes like oxygen barrier films, while maintaining exposure performance across different color resists.
Implementation Method 1
a gas supply unit which supplies one of air and a mixed gas containing air and an inert gas to a local space, between a final surface of the projection optical system and the substrate held by the substrate stage, of the space
Implementation Method 2
a detector which detects a position of an alignment mark, formed on the substrate, and a position of a reference mark, formed on the substrate stage
Implementation Method 3
exposes a resist, formed on a substrate, via a projection optical system in accordance with a recipe
Data Source
AI summary
An exposure apparatus includes an atmosphere maintaining unit which maintains an exposure chamber in an air atmosphere, a gas supply unit which supplies air or a mixed gas containing air and an inert gas to a local space, between a final surface of a projection optical system and a substrate, a detector which detects an alignment mark and a reference mark formed on the substrate stage, and a controller. The controller controls the gas supply unit not to supply the mixed gas to the local space when the detector detects the reference mark, and controls the gas supply unit to supply the mixed gas to the local space when an instruction to detect the alignment mark upon setting the local space in a mixed gas atmosphere, and expose the substrate based on the detection results of the reference mark and the alignment mark is issued from the recipe.