Lithographic Mask Sidelobe Suppression via Parameter Optimization
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Solution Overview
Problem
Conventional lithographic techniques, particularly those using attenuated phase shift masks, face challenges with sidelobe formation due to constructive interference between closely spaced features, leading to unwanted images and reduced manufacturing yield, especially in deep submicron semiconductor manufacturing.
Innovation Solution
A method for configuring the optical transfer of a mask pattern onto a substrate involves calculating the size of printed sidelobes and determining lithographic parameters to optimize high latitude and minimize sidelobe size, using a lithographic apparatus with a processor to adjust beam intensity distribution and illumination shape to prevent sidelobe formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If attenuated phase shift masks are used to achieve high resolution and process latitude, then pattern resolution and manufacturing capability are improved, but sidelobe formation occurs due to constructive interference between adjacent clear features
Solution Approach 1:
The patent applies parameter changes by systematically varying lithographic parameters (illumination NA, source shape, mask attenuator density, focus conditions) to find optimal settings that suppress sidelobe formation. The optimization process adjusts these parameters to balance main feature printing quality with sidelobe suppression, directly addressing the contradiction between achieving high resolution and preventing harmful sidelobes.
2Productivity
If closely spaced clear features are printed using conventional lithographic parameters, then manufacturing throughput is maintained, but unwanted sidelobe images are generated on the substrate
Solution Approach 1:
The patent implements preliminary action by performing comprehensive sidelobe calculations and optimizations during the mask design and lithographic process setup phase. By calculating expected sidelobe positions and intensities beforehand and pre-optimizing parameters to suppress them, the system prevents sidelobe formation before exposure, ensuring both high throughput and pattern fidelity without requiring post-processing corrections.
3Device complexity
If standard illumination conditions are used for deep submicron patterning, then process simplicity is maintained, but resolution limits are reached due to decreased depth of focus
Solution Approach 1:
The patent applies dynamics by implementing adaptive illumination strategies where illumination numerical aperture and source shape are dynamically adjusted based on the specific pattern being printed. Rather than using fixed standard illumination conditions, the system optimizes illumination parameters for each patterning task, enabling maintained depth of focus and resolution for deep submicron features while keeping the overall process manageable through automated optimization.
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 effectively reduces sidelobe formation, enhancing manufacturing yield by optimizing lithographic parameters to prevent unwanted features from being transferred onto the substrate, thereby improving the precision and reliability of semiconductor fabrication.
Implementation Method 1
The halftone film is chosen to desirably shift the phase of the radiation it transmits by 180 degrees
Implementation Method 2
In this manner, destructive interference occurs between some diffracted waves which can be beneficial for imaging
Implementation Method 3
sidelobes, which are unwanted images in the final pattern caused by constructive interference between adjacent clear features in the mask pattern
Implementation Method 4
a projection system configured to project the patterned beam onto a target portion of the substrate
Data Source
AI summary
A method for configuring the optical transfer of a mask pattern onto a substrate using a lithographic apparatus is presented. In an embodiment of the invention, the method includes calculating a size of a printed sidelobe to be generated as a result of optical transfer of the mask pattern onto the substrate; and determining a plurality of lithographic parameters for optical transfer of the mask pattern onto the substrate that yields an optimization of a high latitude for the mask pattern and a small printed sidelobe size.