Excimer Laser Exposure Control for Reticle-Specific Resolution
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Solution Overview
Problem
Current semiconductor exposure systems face challenges in maintaining high resolution due to chromatic aberrations caused by wide spectral linewidths of KrF and ArF excimer laser light, which affects the performance of projection lenses and the manufacturing of miniaturized semiconductor devices.
Innovation Solution
The exposure system employs a laser apparatus that outputs pulsed laser light, an illumination optical system, and a reticle stage, with a processor controlling the laser output and reticle movement to adjust parameters based on different regions of the reticle pattern, ensuring optimal exposure conditions for high-resolution and low-resolution areas by changing the wavelength and spectral linewidth of the pulsed laser light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If KrF or ArF excimer laser light with wide spectral linewidth is used for exposure, then the exposure process can be performed, but chromatic aberrations occur in the projection lens causing resolution decrease
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the spectral linewidth of the laser light according to the pattern density of different reticle regions. For low-density patterns, a wider spectral linewidth is used to improve exposure efficiency, while for high-density patterns, a narrower spectral linewidth is used to reduce chromatic aberrations and maintain resolution. This is achieved through a line narrowing module that can vary the spectral characteristics of the laser light during the exposure process.
2Manufacturing precision
If a line narrowing module is provided in the laser resonator to narrow the spectral linewidth, then chromatic aberrations are reduced and resolution is maintained, but the spectral linewidth becomes too narrow reducing exposure efficiency
Solution Approach 1:
The patent applies local quality by matching the spectral linewidth of the laser light to the specific requirements of different reticle regions. Low-density pattern regions are exposed with wider spectral linewidth light for higher efficiency, while high-density pattern regions are exposed with narrower spectral linewidth light for better resolution. This localized optimization of spectral parameters ensures that each region receives the most appropriate exposure conditions for its pattern density.
3Manufacturing precision
If the spectral linewidth is narrowed to maintain resolution, then chromatic aberrations are minimized, but the exposure time increases reducing productivity
Solution Approach 1:
The patent applies dynamics by making the spectral linewidth adjustable and variable during the exposure process. The line narrowing module can dynamically change the spectral linewidth based on the pattern density being exposed, allowing the system to optimize between resolution and exposure time for different regions of the reticle. This dynamic adaptation eliminates the need to maintain a consistently narrow spectral linewidth across all patterns.
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 improves the performance and yield of semiconductor devices by allowing precise control of laser light parameters on a pulse basis, optimizing exposure conditions for each region, thereby enhancing the manufacturing process.
Implementation Method 1
a laser apparatus configured to output the pulsed laser light
Implementation Method 2
an illumination optical system configured to guide the pulsed laser light to the reticle
Data Source
AI summary
An exposure system according to an aspect of the present disclosure includes a laser apparatus that outputs pulsed laser light, an illuminating optical system that guides the pulsed laser light to a reticle, a reticle stage, and a processor that controls the output of the pulsed laser light from the laser apparatus and the movement of the reticle performed by the reticle stage. The reticle has a first region where a first pattern is disposed and a second region where a second pattern is disposed, and the first and second regions are each a region continuous in a scan width direction perpendicular to a scan direction of the pulsed laser light, with the first and second regions arranged side by side in the scan direction. The processor controls the laser apparatus to output the pulsed laser light according to each of the first and second regions by changing the values of control parameters of the pulsed laser light in accordance with each of the first and second regions.