Illumination Source Selection for Lithography Resolution
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Solution Overview
Problem
Further miniaturization of electronic components, such as integrated circuit chips, is hindered by the limitations of current lithography techniques, where critical dimensions are less than half a wavelength and numerical apertures are close to one, making it difficult to improve resolution and feature density without extensive trial-and-error iterations and numerous experiments.
Innovation Solution
A method is developed to enhance multiple feature lithography by generating maps that predict the quality of circuit features for each point source in the illumination field, allowing for the selection of point sources that meet a predetermined quality threshold, thereby optimizing the illumination system and improving exposure capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the wavelength of light is reduced and numerical aperture is increased to improve resolution, then manufacturing precision is improved, but device complexity increases and further miniaturization becomes increasingly difficult
Solution Approach 1:
The patent changes the parameters of the illumination system by selecting specific illumination angles and source distributions (e.g., annular, dipole, quadrupole configurations) to optimize imaging conditions. This allows adjustment of the illumination characteristics without changing the fundamental lithography system, thereby improving resolution while managing complexity through parameter optimization rather than system redesign.
2Manufacturing precision
If optical proximity corrections and phase shifting techniques are adopted to improve resolution, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by tailoring the illumination conditions specifically for different feature types and pattern densities on the mask. By using computational methods to determine optimal illumination parameters for specific pattern classes, the system achieves improved resolution for critical features without applying complex corrections uniformly across all features, thereby reducing overall system complexity.
Solution Approach 2:
The patent performs preliminary computational analysis of the pattern set to identify critical features and determine optimal illumination parameters before actual lithography. This pre-characterization allows the selection of illumination conditions that will work well for the specific pattern set, avoiding the need for extensive trial-and-error experiments during production and reducing device complexity.
3Manufacturing precision
If trial-and-error iterations and numerous experiments are conducted to optimize lithography, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The patent performs preliminary computational optimization of illumination parameters using representative test patterns before production lithography. By simulating and evaluating different illumination conditions computationally, the system identifies optimal parameters in advance, significantly reducing the number of physical trial-and-error iterations needed and thereby improving productivity while maintaining manufacturing precision.
Solution Approach 2:
The patent uses computational models and simulations as copies of the actual lithography process to predict imaging outcomes. By creating virtual representations of the lithography process and testing illumination parameters in silico, the system avoids numerous physical experiments, thus improving productivity while still achieving the manufacturing precision needed for optimized illumination parameter selection.
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 improved optimization of the illumination system by modeling feature quality and selecting suitable point sources, enhancing the imaging process and reducing the complexity of finding optimal lithography solutions, thus facilitating further miniaturization and feature density in electronic components.
Implementation Method 1
a projection system operable to image the mask features onto the wafer
Implementation Method 2
with critical dimensions of some features now significantly less than half of a wavelength
Data Source
AI summary
According to one embodiment of the invention, a method for enhancing multiple feature lithography is provided. The method includes generating a plurality of maps each associated with a particular one of a plurality of circuit features. Each map maps an illumination field comprising a plurality of point sources and indicates, in terms of a process metric and for each point source, a level of feature quality that will result from using the each point source to image the each circuit feature. The method also includes identifying, based on the maps, a group of one or more of the point sources that, if used to image the circuit features onto a target surface, will result in an overall feature quality level equal to or greater than a predetermined quality threshold.