Lithographic Method Chromatic Aberration Spectrum Control
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Solution Overview
Problem
Current lithographic methods face challenges in accurately controlling the dimension and position of pattern features, particularly at low k1 values, due to limitations in wavelength-dependent aberrations and focus control, which affect sidewall angles and overlay precision in processes like DRAM and 3DNAND flash memory production.
Innovation Solution
A method involving a radiation beam with multiple wavelength components, where the spectrum is controlled to adjust the plane of best focus and dose distribution, allowing for precise control over pattern feature dimensions and positions by exploiting chromatic aberrations, enabling higher spatial frequency corrections and improved overlay control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single wavelength radiation beam is used, then the imaging system is simpler to control, but the ability to control pattern feature dimension and position is limited
Solution Approach 1:
The patent applies dynamics by making the radiation beam spectrum adjustable and variable during the lithographic exposure process. The spectrum of the radiation beam is dynamically controlled to shift between different wavelength ranges, allowing the plane of best focus to be adjusted corresponding to different depths within the resist layer. This enables precise control of pattern feature dimensions and positions at different focal planes without requiring multiple separate exposure steps or complex mechanical adjustments.
2Adaptability or versatility
If the plane of best focus is fixed, then the imaging system is more stable, but the ability to address depth variations in the resist layer is limited
Solution Approach 1:
The patent applies parameter changes by varying the wavelength parameter of the radiation beam to adjust the plane of best focus. By changing the spectral composition of the radiation beam, the focal plane is shifted to different depths within the resist layer. This allows the imaging system to adapt to different resist layer depths and process conditions while maintaining stable imaging through controlled spectral adjustment rather than mechanical instability.
3Manufacturing precision
If sophisticated fine-tuning steps are applied to achieve low k1 lithography, then smaller features can be formed, but the process complexity and difficulty increase
Solution Approach 1:
The patent applies parameter changes by controlling the spectrum of the radiation beam to achieve low k1 lithography. By adjusting the wavelength composition and plane of best focus, precise control of critical dimensions is achieved without requiring multiple separate fine-tuning steps. The spectral control provides a direct mechanism to optimize the imaging process for low k1 values, reducing the need for complex iterative adjustments of illumination schemes, phase shifting, or optical proximity correction.
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 enables precise control over pattern feature dimensions and positions, enhancing the accuracy and reliability of lithographic processes, particularly in low k1 regimes and for applications like DRAM and 3DNAND flash memory, by dynamically adjusting the radiation beam spectrum during exposure.
Implementation Method 1
wherein a plane of best focus of the image is dependent on a wavelength of the radiation beam
Implementation Method 2
controlling a spectrum of the radiation beam in dependence on one or more parameters of one or more subsequent processes applied to the substrate to form the pattern feature so as to control a dimension and/or position of the pattern feature
Data Source
AI summary
A method of forming a pattern on a substrate using a lithographic apparatus provided with a patterning device and a projection system having chromatic aberrations, the method including: providing a radiation beam having a plurality of wavelength components to the patterning device; forming an image of the patterning device on the substrate using the projection system to form the pattern, wherein a position of the pattern is dependent on a wavelength of the radiation beam due to the chromatic aberrations; and controlling a spectrum of the radiation beam to control the position of the pattern.