Humidified Purge Gas Control for Dew-Free Exposure Optics
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Solution Overview
Problem
Existing exposure apparatuses face issues with dew condensation due to excessive humidifying performance and control defects from insufficiency in humidifying performance, particularly when using humidified air for local purging of optical elements, leading to illumination deterioration and reduced productivity.
Innovation Solution
An exposure apparatus with a humidified air supply device that includes a humidifier, flow rate regulators, a humidity sensor, and a controller to adjust the flow rate ratio of humidified and non-humidified gases, and variable instruments to maintain consistent humidifying performance, ensuring accurate humidity control and preventing dew condensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the amount of circulation air within the booth is increased to suppress fogging on optical elements, then the illumination deterioration is reduced, but the amount of chemical pollutants to be removed increases, resulting in reduced lifetime of the chemical filter
Solution Approach 1:
The air circulation system is segmented into two separate systems: a first circulation system that recirculates air through chemical filters to remove pollutants, and a second circulation system that recirculates air through dehumidifiers to control humidity. This segmentation allows each system to be optimized independently, preventing the cross-contamination of functions and enabling the second system to suppress fogging without increasing the pollutant load on the first system's filters.
Solution Approach 2:
A humidity sensor is introduced as an intermediary device to detect humidity levels in the booth and provide feedback to the control system. This intermediary enables precise monitoring and control of humidity, allowing the dehumidification system to respond dynamically to environmental changes and suppress fogging on optical elements without requiring excessive air circulation that would overwhelm the chemical filters.
2Reliability
If the face velocity in the plane of the chemical filter is reduced by selecting a filter with larger opening, then the adsorption efficiency is improved, but the device size increases
Solution Approach 1:
The air treatment function is segmented between two separate circulation systems: one dedicated to chemical filtration and another dedicated to humidity control. By separating these functions, the chemical filter system can operate at optimal face velocity for maximum adsorption efficiency without being overloaded by the additional air volume required for humidity management, thereby maintaining high reliability without requiring oversized filters.
Solution Approach 2:
The system changes the operational parameters by introducing a separate humidity control loop that operates independently from the chemical filtration loop. This parameter separation allows the chemical filter to maintain its design face velocity and adsorption efficiency while the humidity system handles the bulk air circulation needed for fogging prevention, avoiding the need to increase filter size.
3Duration of action of stationary object
If multiple chemical filters are provided to extend replacement cycle, then the filter lifetime is extended, but the device complexity and size increase
Solution Approach 1:
The air treatment function is segmented into two independent circulation systems: a chemical filtration system and a humidity control system. This segmentation ensures that the chemical filters only handle pollutant removal from a portion of the air, while the humidity system handles the bulk air circulation and dehumidification. As a result, the chemical filters experience reduced load and extended lifetime without requiring multiple redundant filter units, thereby avoiding increased device complexity.
Solution Approach 2:
The system changes the operational parameters by introducing a separate humidity control loop that operates independently from the chemical filtration loop. This parameter separation allows the chemical filter system to operate at reduced capacity with extended service intervals, while the humidity system handles the additional air circulation requirements, avoiding the need to multiply the number of chemical filters.
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 solution effectively suppresses dew condensation and control defects, maintaining stable humidity levels and improving alignment accuracy, thereby enhancing the exposure apparatus's performance and productivity.
Implementation Method 1
a vaporizing humidifier (34) that humidifies the clean dry air (32) to thereby generate humidified air (41)
Implementation Method 2
a gas mixer (40) that mixes the humidified air (41) and the clean dry air (32) to thereby generate the humidified air (41)
Data Source
AI summary
The exposure apparatus includes a purge member that includes a humidifier that humidifies supplied gas; a first regulator that regulates a flow rate of first gas which passes through the humidifier; a second regulator that regulates a flow rate of second gas which does not pass through the humidifier; a variable instrument that varies a humidifying performance of the humidifier; a sensor; and a controller. Here, the controller controls the first and the second regulators to adjust a flow rate ratio of the first gas and the second gas on the basis of the humidity of the humidified gas detected by the sensor and a pre-set target humidity, and controls the variable instrument to keep the flow rate of the first gas constant on the basis of an amount of operation of the first regulator and an amount of pre-set target operation.