EUV LED Illuminance Stabilization via Dummy Light Emission
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Solution Overview
Problem
In semiconductor device manufacturing, extreme ultraviolet (EUV) exposure methods face challenges with unstable light emission from LED light sources due to temperature variations, leading to inconsistent line widths in circuit patterns and reduced yield, especially when there are pauses between processing cycles.
Innovation Solution
A substrate processing apparatus that includes a light source unit with a control unit to maintain constant average illuminance by performing dummy light emission during non-processing cycles, adjusting the illuminance based on the processing cycle's illuminance to stabilize the light emission state and heat generation, thereby ensuring stable exposure across substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the LED light source operates without stabilization during pauses between processing cycles, then productivity is improved by reducing idle time, but the light emission state becomes unstable causing line width variation
Solution Approach 1:
The system performs preliminary stabilization actions by controlling the LED to emit light at a predetermined illuminance during pause periods before actual processing. This preliminary action ensures the LED temperature and emission characteristics are stabilized before the next processing cycle begins, preventing line width variation while maintaining high productivity.
2Manufacturing precision
If the LED illuminance is increased to improve exposure quality, then manufacturing precision is improved, but heat generation increases causing temperature instability
Solution Approach 1:
The system uses periodic action by controlling the LED to operate at high illuminance only during necessary processing periods, while during pause periods it operates at a lower predetermined illuminance level. This periodic modulation allows the LED to stabilize temperature during pauses while still achieving high-quality exposure during processing, resolving the contradiction between exposure quality and temperature stability.
3Manufacturing precision
If a luminance sensor and feedback control are used to maintain constant illuminance, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The system applies self-service by using the measured illuminance from the luminance sensor during processing to automatically determine and set the appropriate predetermined illuminance level for subsequent pause periods. This self-determined parameter approach maintains constant average illuminance without requiring complex real-time feedback control systems, achieving manufacturing precision while keeping device complexity manageable.
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 approach stabilizes the light emission state and heat generation of the LED light source, ensuring consistent line widths and improved yield by maintaining uniform average illuminance across substrates, even during temperature fluctuations and pauses between processing cycles.
Implementation Method 1
a light source unit configured to irradiate light to the substrate placed on the placing unit, an emission state of the light source unit being varied depending on a temperature thereof
Implementation Method 2
A temperature of the LED is determined based on heat generation of the LED itself and ambient temperature
Data Source
AI summary
A period from a time point when a wafer W is carried into a housing 10 to a time point when the wafer W after being exposed is completely ready to be carried out is set as a single cycle. A time period before a next cycle is begun and after the single cycle is completed is referred to as a standby time period. When an illuminance in dummy light emission is set to be Id; an illuminance in exposure, Is; a time length of the dummy light emission, Td; and a time length of the exposure, Ts, by setting the Id to satisfy an expression of Id=(Tp/Td)·Iw−(Ts/Td)·Is, an average illuminance within the single cycle is maintained constant between substrates.