Line Narrowed Laser Apparatus Spectral Width Control
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Solution Overview
Problem
Current semiconductor exposure technologies face challenges in narrowing the spectrum width of excimer laser beams, leading to chromatic aberration and reduced resolving power due to the wide natural oscillation spectrum widths of KrF and ArF excimer laser apparatuses, which affects the precision of semiconductor lithography processes.
Innovation Solution
A line narrowed laser apparatus is configured with a laser resonator, electrodes, pulsed voltage sources, a wavelength selecting element, and a controller that measures duty and suspension periods to control the spectral width varying unit, allowing for precise adjustment of the spectral width to minimize chromatic aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a line narrow element is added to narrow the spectrum width, then chromatic aberration is reduced, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by controlling the spectral width varying unit before the second burst oscillation to pre-adjust the spectral width to an appropriate value. This prevents chromatic aberration from occurring in the first place rather than correcting it afterward, while avoiding the need for complex real-time correction systems.
Solution Approach 2:
The patent implements feedback control by measuring the duty and suspension period, then using these measurements to control the spectral width varying unit. The controller adjusts the spectral width based on feedback from the measured parameters, creating a closed-loop system that maintains optimal spectral width without requiring complex manual intervention.
2Manufacturing precision
If the spectral width is narrowed to improve resolving power, then manufacturing precision improves, but the device complexity increases due to additional control mechanisms
Solution Approach 1:
The controller performs preliminary adjustment of the spectral width before the second burst oscillation by controlling the spectral width varying unit. This ensures that the spectral width is optimized in advance for high resolving power, eliminating the need for complex real-time adjustment mechanisms during operation.
Solution Approach 2:
The patent changes physical parameters by controlling the spectral width varying unit to adjust the spectral width to an appropriate value. This parameter adjustment directly improves resolving power by narrowing the spectral width, while the control is achieved through relatively simple mechanisms that monitor duty and suspension period.
3Productivity
If burst oscillations are performed with short suspension periods to increase productivity, then productivity improves, but spectral width control becomes more difficult
Solution Approach 1:
The patent applies feedback control by measuring both the duty and the suspension period, then using these measurements to control the spectral width varying unit. This feedback mechanism allows the system to automatically adjust the spectral width based on the actual suspension period, making spectral width control feasible even with short suspension periods between burst oscillations.
Solution Approach 2:
The patent implements dynamic control by adjusting the spectral width based on the measured suspension period. The controller dynamically modifies the spectral width varying unit's operation according to the actual timing conditions, enabling effective spectral control adaptable to varying productivity requirements including short suspension periods.
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 narrows the spectral width of the laser beam, reducing chromatic aberration and enhancing the resolving power of semiconductor exposure systems, thereby improving the precision and accuracy of semiconductor lithography processes.
Implementation Method 1
a spectral width varying unit provided in the laser resonator... perform a first control of the spectral width varying unit based on the duty and the length of the suspension period
Implementation Method 2
a wavelength selecting element provided in the laser resonator... To narrow the spectrum width, a laser resonator of a gas laser apparatus is equipped with a line narrow module having a line narrow element. The line narrow element may be an etalon, a grating, or the like.
Data Source
AI summary
The line narrowed laser apparatus configured to perform a plurality of burst oscillations including a first burst oscillation and a second burst oscillation next to the first burst oscillation to output a pulse laser beam. The line narrowed laser apparatus comprises a laser resonator, a chamber provided in the laser resonator, a pair of electrodes provided in the chamber, an electric power source configured to apply pulsed voltage to the pair of electrodes, a wavelength selecting element provided in the laser resonator, a spectral width varying unit provided in the laser resonator, and a controller. The controller is configured to measure a duty in a predetermined period before starting the second burst oscillation and a length of a suspension period from a time of ending the first burst oscillation to a time of starting the second burst oscillation, and perform a first control of the spectral width varying unit based on the duty and the length of the suspension period.