Optical Unit With Dual Spatial Light Modulators For Illumination Control
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Solution Overview
Problem
Existing exposure apparatuses face challenges in achieving a wide variety of illumination conditions for the illumination pupil luminance distribution, which is crucial for accurately transferring fine patterns onto a wafer, as they often rely on limited adjustable optical systems.
Innovation Solution
The implementation of an optical unit comprising a light splitter, two spatial light modulators with individually controlled optical elements, and a light combiner to create a versatile illumination optical apparatus that can form diverse light intensity distributions on the illumination pupil, allowing for precise control of the illumination conditions based on the pattern characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional illumination optical apparatus with limited adjustable optical systems is used, then the device complexity is reduced, but the adaptability of illumination conditions (shape and size of illumination pupil luminance distribution) is insufficient
Solution Approach 1:
The incident beam is divided into multiple separate beams by a beam splitter, with each beam being independently processed by individual spatial light modulators. This segmentation allows each beam to be controlled separately to form different light intensity distributions, thereby achieving diverse illumination conditions without requiring a single complex adjustable system.
Solution Approach 2:
The patent transitions from controlling a single beam to controlling multiple beams in parallel, adding the dimension of beam multiplicity. By arranging multiple spatial light modulators to process different beams simultaneously, the system achieves greater adaptability in illumination conditions while keeping each individual modulator relatively simple.
2Adaptability or versatility
If multiple spatial light modulators with individual control are introduced to achieve diverse illumination conditions, then the adaptability of illumination conditions is improved, but the device complexity increases
Solution Approach 1:
Multiple beams processed by different spatial light modulators are merged back together by a beam combiner to form a single composite beam. This merging allows the system to achieve diverse illumination conditions through multiple parallel processing paths while maintaining a unified optical output path, thereby managing complexity through modular architecture.
Solution Approach 2:
Each spatial light modulator is designed to perform the same basic function of shaping light intensity distribution, but they work in parallel on different beams. This universal design allows the system to achieve multiple illumination conditions through combinatorial control of identical components, reducing the need for specialized components for each function.
3Adaptability or versatility
If the incident beam is divided into multiple beams for independent processing, then the illumination conditions adaptability is enhanced, but the loss of time for beam processing increases
Solution Approach 1:
Multiple beams are processed simultaneously in parallel rather than sequentially. While the beam is split into multiple paths, all spatial light modulators operate at the same time on their respective beams, and the beams are recombined without waiting for sequential processing. This parallel processing maintains continuity of useful action and eliminates time loss that would occur with sequential beam processing.
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 solution enables the exposure apparatus to achieve good exposure results by providing a wide range of illumination conditions, ensuring accurate pattern transfer and improved optical performance, such as enhanced depth of focus and high contrast on the wafer.
Implementation Method 1
a light splitter to split an incident beam traveling in an incident light path, into a plurality of beams
Implementation Method 2
a first spatial light modulator which can be arranged in an optical path of a first beam out of the plurality of beams; a second spatial light modulator which can be arranged in an optical path of a second beam out of the plurality of beams
Implementation Method 3
a light combiner to combine a beam having passed via the first spatial light modulator, with a beam having passed via the second spatial light modulator, and to direct a resultant beam to an exiting light path
Data Source
AI summary
An illumination optical apparatus has an optical unit. The optical unit has a light splitter to split an incident beam into two beams; a first spatial light modulator which can be arranged in an optical path of a first beam; a second spatial light modulator which can be arranged in an optical path of a second beam; and a light combiner which combines a beam having passed via the first spatial light modulator, with a beam having passed via the second spatial light modulator; each of the first spatial light modulator and the second spatial light modulator has a plurality of optical elements arranged two-dimensionally and controlled individually.