EUV Illumination Pixel Polarization for Pattern Contrast and Throughput
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Solution Overview
Problem
As semiconductor device sizes shrink, lithography technologies face resolution issues due to optical restrictions, leading to reduced lithography performance, contrast, throughput, yield, and increased defects.
Innovation Solution
An illumination system for EUV lithography systems is configured with pixels that can be polarized in various configurations, including transverse electric (TE) and transverse magnetic (TM) polarization, allowing for free-form polarization to enhance pattern contrast and exposure operation throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography is used to maintain current device sizes, then existing optical systems can be used, but resolution and lithography performance deteriorate as device sizes shrink
Solution Approach 1:
The patent changes the fundamental parameter of light wavelength from conventional ranges to extreme ultraviolet (EUV) range (13.5 nanometers), enabling resolution of much smaller semiconductor device features. This parameter change allows the lithography system to overcome optical restrictions and achieve the required manufacturing precision for shrinking device sizes.
Solution Approach 2:
The patent replaces conventional optical systems with reflective optics specifically designed for EUV wavelengths. This substitution involves using multilayer reflective coatings (such as Mo/Si alternating layers) instead of conventional transmissive optics, enabling the system to operate at the required wavelength and achieve the necessary resolution.
2Manufacturing precision
If EUV lithography with reflective optics is used to achieve smaller device sizes, then lithography resolution improves, but system complexity and manufacturing difficulty increase
Solution Approach 1:
The patent segments the optical system into multiple reflective elements with specific functions: illumination optics to condition the EUV light, reflective lenses to focus and direct beams, and multilayer mirrors for wavelength-specific reflection. This segmentation allows each component to be optimized independently for EUV operation, managing the overall system complexity.
Solution Approach 2:
The patent employs composite multilayer structures (such as alternating layers of molybdenum and silicon) for reflective optics. These composite materials are specifically engineered to reflect EUV wavelengths while managing the complexity of creating optics that can operate at such short wavelengths. The multilayer structure provides the necessary optical properties that single-material optics cannot achieve.
3Manufacturing precision
If polarization control is added to enhance pattern contrast, then lithography performance improves, but device complexity increases
Solution Approach 1:
The patent applies polarization control locally at different regions of the illumination system rather than uniformly across the entire system. By selectively applying polarization conditioning in specific areas where it most impacts pattern contrast, the system achieves improved lithography performance while minimizing the added complexity to the overall illumination system.
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
The system improves pattern contrast and throughput while reducing defects, enhancing semiconductor device yield and performance by tailoring radiation polarization to specific exposure patterns.
Implementation Method 1
The multilayer polarizer is configured to polarize the unpolarized extreme ultraviolet radiation into transverse electric and transverse magnetic components
Implementation Method 2
The transmissive extreme ultraviolet optical element is configured to transmit the transverse magnetic polarized extreme ultraviolet radiation and block the transverse electric polarized extreme ultraviolet radiation
Data Source
AI summary
An illumination system includes a plurality of pixels (or spots) that are (or may be) configured in one or more polarization configuration types. The pixels of the illumination system may be configured to promote particular types of polarization (e.g., transverse electric (TE) polarization, transvers magnetic (TM) polarization) to increase pattern contrast while achieving suitable exposure operation throughput. Moreover, the pixels of the pixels of the illumination system may be configured to achieve free-form (arbitrary or freely-configurable) polarization, which permits the polarization of radiation to be tailored to particular exposure operation patterns and other parameters.