Droplet Generator Maintenance With Continuous Nozzle Heating
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Solution Overview
Problem
The challenge in extreme ultraviolet lithography (EUVL) is maintaining consistent droplet generation for efficient EUV radiation production, as fluctuations in droplet size and arrival time affect the stability and efficiency of the laser-produced plasma (LPP) source, leading to increased downtime during maintenance and recalibration due to temperature changes in the nozzle.
Innovation Solution
A droplet generator maintenance system with a coolant distribution unit and gas supply unit, including a heat exchange assembly and air heating assembly, maintains the nozzle temperature during servicing, using a three-way valve and dual temperature three-way valve to control gas flow for efficient temperature regulation, reducing downtime by ensuring consistent droplet generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the nozzle temperature is allowed to change during maintenance, then the servicing process is simpler and faster, but the droplet generation consistency deteriorates, leading to increased downtime
Solution Approach 1:
The system performs preliminary heating of the nozzle to a target temperature before maintenance begins, and maintains this temperature throughout the servicing process. This preliminary action ensures that when maintenance is completed, the nozzle is already at the correct temperature for consistent droplet generation, eliminating the need for post-maintenance temperature adjustments and reducing downtime.
Solution Approach 2:
The heating assembly continuously maintains the nozzle at the target temperature throughout the entire maintenance process. Rather than allowing the temperature to drop during servicing and then reheating afterward, the system sustains the thermal condition continuously, ensuring droplet generation consistency is preserved throughout and eliminating downtime associated with temperature recovery.
2Reliability
If the nozzle temperature is maintained during servicing, then droplet generation consistency is preserved, but the device complexity increases due to additional temperature control systems
Solution Approach 1:
The heating assembly is designed to automatically maintain the nozzle at the target temperature without requiring external intervention or complex control systems. The system self-regulates the heating process, turning the heating element on or off as needed to keep the nozzle at the desired temperature, thereby simplifying the overall control architecture while maintaining temperature stability.
Solution Approach 2:
The system controls temperature by simply adjusting the power state of the heating assembly (on/off states) rather than using complex variable control mechanisms. This binary parameter approach simplifies the control system while effectively maintaining the nozzle at the target temperature, reducing device complexity compared to systems requiring precise variable control.
3Object-affected harmful factors
If the droplet generator is depressurized and cooled for maintenance, then component safety is improved, but the operational efficiency decreases due to extended downtime
Solution Approach 1:
The nozzle is heated to the target temperature before maintenance begins, and this thermal state is maintained throughout the depressurization and servicing process. This preliminary and sustained heating action ensures that when the nozzle is repressurized, it is already at the correct operating temperature, eliminating the need for post-maintenance heating and reducing downtime.
Solution Approach 2:
The heating assembly maintains continuous thermal conditioning of the nozzle throughout the entire maintenance cycle, including during depressurization and servicing. This continuity ensures that the nozzle remains at the target temperature despite pressure changes, allowing immediate resumption of droplet generation after maintenance and maximizing operational efficiency.
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 system reduces EUVL tool downtime by maintaining droplet generator temperature stability, enabling efficient and consistent droplet production, thereby enhancing the operational efficiency of EUVL tools.
Implementation Method 1
The gas supply unit includes a heat exchange assembly and an air heating assembly
Implementation Method 2
The coolant distribution unit provides a pressurized gas from a booster box of the coolant distribution unit to an orifice of the droplet generator
Data Source
AI summary
A photolithographic apparatus includes a droplet generator, a droplet generator maintenance system, and a controller communicating with the droplet generator maintenance system. The droplet generator maintenance system operatively communicates with the droplet generator, a coolant distribution unit, a gas supply unit, and a supporting member. The gas supply unit includes a heat exchange assembly and an air heating assembly. The coolant distribution unit is configured to control the temperature of the droplet generator within the acceptable droplet generator range.