Line-Narrowed Gas Laser Control for Wavelength Energy Ratio
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Solution Overview
Problem
In semiconductor exposure apparatuses, the wide spectrum line width of KrF and ArF excimer laser beams leads to chromatic aberration, reducing resolving power, which necessitates the narrowing of the spectrum line width to minimize aberration effects.
Innovation Solution
A line narrowed gas laser apparatus with an optical resonator including an adjustment mechanism to control the energy ratio of first and second wavelength components, utilizing a processor to store and apply relation data for precise adjustment of the energy ratio, enabling accurate control of the pulse laser beam for improved exposure processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a line narrowing module is provided in the laser resonator to narrow the spectrum line width, then chromatic aberration is reduced and resolving power is improved, but the device complexity increases
Solution Approach 1:
The patent extracts and separates the wavelength control function from the main laser resonator by introducing a dedicated line narrowing module with independent wavelength selection elements (etalon or grating). This allows the core laser generation to remain simple while the wavelength precision is enhanced through the added module, resolving the contradiction between simplicity and precision.
Solution Approach 2:
The line narrowing module acts as an intermediary component between the laser resonator and the exposure apparatus. It includes wavelength selection elements that selectively transmit specific wavelength components while filtering others, thereby mediating the spectral composition to achieve narrow line width without fundamentally altering the laser resonator structure.
2Manufacturing precision
If the spectrum line width is narrowed using a line narrowing module, then imaging performance is enhanced, but the device complexity and control difficulty increase
Solution Approach 1:
The patent implements feedback control by monitoring the actual wavelength or energy ratio output and comparing it with the target value. The control unit adjusts the line narrowing module parameters based on this feedback to maintain the desired wavelength precision and energy ratio, thereby simplifying operation despite the added complexity of the module.
Solution Approach 2:
The patent controls the line narrowing module by adjusting key parameters such as the incident angle on the grating or the position of the etalon, which directly affect the selected wavelength and energy ratio. By providing pre-stored relation data between these parameters and the output characteristics, the system enables precise control through simple parameter adjustment rather than complex operations.
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 adjusts the energy ratio of the pulse laser beam, enhancing the imaging performance and allowing for precise control of the resist film exposure, thereby improving the sectional shape and angle accuracy relative to the semiconductor wafer surface.
Implementation Method 1
an optical resonator including an adjustment mechanism configured to adjust a parameter of an energy ratio of the first wavelength component and the second wavelength component
Implementation Method 2
a line narrowed gas laser apparatus configured to emit a pulse laser beam including a first wavelength component and a second wavelength component
Data Source
AI summary
A control method for a line narrowed gas laser apparatus is a control method for a line narrowed gas laser apparatus configured to emit a pulse laser beam including a first wavelength component and a second wavelength component. The apparatus includes a laser chamber including a pair of electrodes, an optical resonator including an adjustment mechanism configured to adjust a parameter of an energy ratio of the first and second wavelength components, and a processor in which relation data indicating a relation of the parameter of the energy ratio with a control parameter of the adjustment mechanism is stored. The control method includes receiving a command value of the parameter of the energy ratio from an external device, and acquiring, based on the relation data, a value of the control parameter corresponding to the command value and controlling the adjustment mechanism based on the value of the control parameter.