Polarization Splitting Illumination Optical Device for Lithography
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Solution Overview
Problem
Conventional illumination optical apparatuses for lithography processes face challenges in achieving precise control over light quantity distribution and polarization states on the pupil plane, limiting the flexibility and accuracy in illuminating reticle surfaces for semiconductor device manufacturing.
Innovation Solution
The proposed solution involves a light splitting device that splits the illumination beam into beams with different polarization states, combined using spatial light modulation devices with individually controllable optical elements, allowing for precise control of light quantity distribution and polarization states on the pupil plane through the modulation of mirror elements' inclination angles and positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a spatial light modulator with variable multi-mirror system is used to control light quantity distribution on the pupil plane, then the illumination uniformity and light distribution control are improved, but the device complexity increases due to the large number of microscopic mirror elements arranged in array form
Solution Approach 1:
The illumination beam is divided into multiple beams with different polarization states using a light splitting device. Each beam is then independently modulated by separate spatial light modulators, allowing complex illumination patterns to be constructed from simpler individual beam contributions, thereby reducing the complexity burden on any single modulator system.
Solution Approach 2:
The system uses multiple spatial light modulators that can handle different polarization states independently. Each SLM serves multiple functions: controlling light quantity distribution, shaping illumination patterns, and managing polarization-specific optical paths, thereby reducing overall system complexity through functional consolidation.
2Measurement precision
If two spatial light modulators are used to control light quantity distributions and polarization states independently, then the control precision over illumination conditions is improved, but the device complexity and cost increase
Solution Approach 1:
The system dynamically routes different polarization state beams to different spatial light modulators based on the required illumination conditions. The light splitting device and optical path configuration allow flexible, real-time assignment of beams to appropriate SLMs, enabling precise polarization control without permanently duplicating the entire SLM system.
Solution Approach 2:
A light splitting device acts as an intermediary between the single light source and multiple spatial light modulators. It separates the illumination beam into different polarization states before they reach the SLMs, allowing each SLM to process specific polarization components independently, thereby achieving precise control with reduced system complexity.
3Adaptability or versatility
If conventional illumination optical apparatus is used, then the device structure is simpler, but the flexibility in setting various illumination conditions and achieving uniform illuminance distribution is limited
Solution Approach 1:
Different regions of the pupil plane receive light with specific polarization states and intensity distributions controlled by dedicated spatial light modulator segments. Each local region can be independently optimized for specific illumination requirements, enabling high flexibility in setting various illumination conditions while maintaining manageable system complexity through localized control.
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 the generation of various polarization states and light distributions, enhancing the accuracy and flexibility of the illumination process, thereby improving the precision of semiconductor device manufacturing by allowing for optimal illumination conditions based on the reticle pattern.
Implementation Method 1
a light splitting device which splits the beam into a plurality of beams with respective polarization states different from each other
Implementation Method 2
a spatial light modulation device which is arranged on at least one of a first optical path in which a first beam out of the plurality of beams travels and a second optical path in which a second beam out of the plurality of beams travels
Data Source
AI summary
According to one embodiment, an illumination optical apparatus comprises: a light splitting device which splits the beam into a plurality of beams with respective polarization states different from each other; a spatial light modulation device which is arranged on at least one of a first optical path in which a first beam out of the plurality of beams travels and a second optical path in which a second beam out of the plurality of beams travels, and which has a plurality of optical elements arranged two-dimensionally and driven individually; and a control device which controls the spatial modulation device to combine the first beam and the second beam at least in part.