Optical Property Measurement Apparatus for Exposure Precision
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Solution Overview
Problem
Current projection exposure apparatuses in semiconductor and liquid crystal display manufacturing face challenges in measuring optical properties, particularly the polarization state and dependencies between optical properties of illumination and projection systems, which affect image resolution and contrast.
Innovation Solution
A dual-optical-property measurement apparatus that converts light into measurement lights to assess optical properties using a common photodetector, allowing for accurate adjustment of optical systems to enhance exposure precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a polarization state measurement method is used to improve resolution and contrast, then image quality is improved, but multiple optical properties (size, shape, position of illumination) must be measured simultaneously, increasing measurement complexity
Solution Approach 1:
The patent combines multiple measurement functions (polarization state, wavefront, pupil image) into a single integrated measurement apparatus that uses one light source and one detector to measure all optical properties simultaneously, resolving the contradiction between improved image quality and measurement system complexity
Solution Approach 2:
The measurement apparatus is designed with multi-functionality to measure polarization state, wavefront, and pupil image properties using a unified measurement system, eliminating the need for separate measurement devices for each optical property
2Manufacturing precision
If polarization direction is varied at different positions within the pupil plane to improve resolution, then image contrast is improved, but the propagating velocity of light becomes dependent on polarization direction due to anisotropic optical elements, creating wavefront differences
Solution Approach 1:
The patent implements feedback by measuring the actual wavefront and polarization state through the optical system and using this information to correct for anisotropic effects, ensuring accurate optical property measurement despite polarization-dependent propagation velocity variations
Solution Approach 2:
The measurement apparatus accounts for polarization-dependent parameter changes by measuring optical properties for different polarization directions and incorporating these variations into the comprehensive optical property assessment
3Measurement precision
If conventional separate measurement methods are used for different optical properties, then each property can be measured independently, but comprehensive measurement of all optical properties becomes time-consuming and complex
Solution Approach 1:
The patent enables continuous measurement of multiple optical properties (polarization state, wavefront, pupil image) in a single uninterrupted measurement sequence using one light source and detector, eliminating the time loss associated with switching between separate measurement systems
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
Enables highly accurate exposure and pattern formation on photosensitive substrates with improved resolution and contrast by measuring and adjusting optical properties, facilitating higher integration and yield in microdevice manufacturing.
Implementation Method 1
a first optical system that converts light incident on the incidence optical system into a first measurement light in order to measure a first optical property... and a second optical system that converts the light incident on the incidence optical system into a second measurement light in order to measure a second optical property
Data Source
AI summary
An optical property measurement apparatus is equipped with an optical system unit that selectively places an opening section for passing illumination light, a microlens array for measuring wavefront aberration, and a polarization detection system for measuring a polarization state of the illumination light on an optical path of the illumination light. Accordingly an illumination shape and a size of an illumination optical system, wavefront aberration of a projection optical system and a polarization state of the illumination light can be measured together. Therefore, for example, even when exposure is performed with polarized illumination that is a type of modified illumination, highly-accurate exposure can be achieved by adjusting various optical systems based on the measurement results.