Semiconductor Exposure Wavelength Control for Overlay Accuracy
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Solution Overview
Problem
Chromatic aberration in semiconductor exposure systems due to wide spectral linewidths of KrF and ArF excimer laser beams leads to reduced resolution, necessitating a method to narrow the spectral linewidth and correct for positional deviations caused by temperature variations and optical element expansion.
Innovation Solution
An exposure method involving setting and adjusting the wavelength of pulse laser beams based on pre-exposure measurement results to correct for positional deviations and chromatic aberration, using a line narrowing module and a lithography control processor to implement wavelength corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a projection lens is formed of a material that transmits ultraviolet light such as KrF and ArF laser beams, then the laser beam can be transmitted through the lens, but chromatic aberration occurs due to wide spectral linewidths (350 pm to 400 pm), causing resolution to decrease
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the wavelength of the laser beam according to the scan field position. Different wavelength settings are used for different regions of the wafer to compensate for chromatic aberration caused by the wide spectral linewidth, thereby maintaining high resolution across the entire exposure field while preserving laser beam transmission through the UV-transmitting lens
2Manufacturing precision
If the spectral linewidth of the laser beam is narrowed using a line narrowing module to reduce chromatic aberration, then resolution improves, but the device complexity increases
Solution Approach 1:
Instead of relying solely on physical line narrowing modules that increase device complexity, the patent uses parameter changes by controlling the wavelength of the laser beam through software-based wavelength setting according to scan field position. This approach achieves chromatic aberration correction while avoiding the added complexity of additional optical components
Solution Approach 2:
The patent replaces the mechanical/optical line narrowing module with a control system that adjusts wavelength parameters. This substitution eliminates the need for physical line narrowing components while achieving the same effect of reducing chromatic aberration and improving resolution
3Manufacturing precision
If pre-exposure is performed to measure positional deviation, then overlay accuracy can be corrected, but the manufacturing process time increases
Solution Approach 1:
The patent applies preliminary action by performing pre-exposure to measure positional deviation before the main exposure process. This allows the system to determine correction values in advance, which are then used to adjust wavelength settings during subsequent exposures, ensuring high overlay accuracy while minimizing the impact on overall manufacturing time through efficient process integration
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
Improves overlay accuracy by correcting for chromatic aberration and positional deviations, ensuring high-resolution imaging and manufacturing of electronic devices with precise alignment.
Implementation Method 1
a first pulse laser beam that scans a first scan field of a first semiconductor wafer
Implementation Method 2
a line narrowing module (LNM) including a line narrowing element (such as etalon or grating) may be provided in order to narrow the spectral linewidth
Data Source
AI summary
An exposure method includes a first step of setting a wavelength of a first pulse laser beam that scans a first scan field of a first semiconductor wafer to a first pattern that changes according to an in-field position along a scanning direction in the first scan field and setting a wavelength of a second pulse laser beam that scans a second scan field of the first semiconductor wafer to a second pattern that changes according to an in-field position along a scanning direction in the second scan field and that is different from the first pattern based on measurement results regarding positional deviation of exposure results by pre-exposure using an exposure apparatus, and a second step of scanning the first scan field with the first pulse laser beam and then scanning the second scan field with the second pulse laser beam using the exposure apparatus.