Exchangeable Pupil Filter Transport Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithographic apparatuses face challenges in maintaining improved imaging capabilities as the numeric aperture increases, leading to reduced depth of focus and complexity, particularly when imaging difficult patterns like contact hole arrays.
Innovation Solution
A lithographic projection apparatus with a transport mechanism that allows for the exchangeable optical elements to be moved in and out of the pupil plane, enabling the use of non-rotationally symmetric pupil filters that match standard dimensions for patterning devices, improving image contrast and resolution without contaminating the sensitive projection system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the numeric aperture of the projection system is increased to improve imaging resolution, then the resolution is improved, but the depth of focus is reduced and the system complexity increases
Solution Approach 1:
The projection system is divided into modular components, with optical elements that can be independently exchanged. The pupil filter is separated as a distinct exchangeable component rather than being integrated into the main projection lens system, allowing independent optimization and maintenance of different system aspects.
Solution Approach 2:
The system incorporates dynamic exchangeability of optical elements during operation. The transport mechanism enables the pupil filter to be moved into and out of the optical path, and exchangeable optical elements can be swapped without opening the housing, allowing the system to adapt its configuration based on imaging requirements.
2Measurement precision
If exchangeable optical elements are used to improve imaging capabilities, then the imaging contrast and resolution are improved, but the risk of contaminating the projection system increases
Solution Approach 1:
A transport mechanism serves as an intermediary between the external environment and the projection system's optical path. This mechanism allows optical elements to be exchanged without opening the housing, creating a protected interface that prevents direct exposure of the projection system to potential contaminants during element exchange.
Solution Approach 2:
The pupil filter and other optical elements are extracted as separate exchangeable components that can be handled and replaced outside the main projection system enclosure. The transport mechanism extracts these elements from the optical path in a controlled manner, isolating the contamination risk to the transport interface rather than the entire projection system.
3Ease of manufacture
If standard-sized patterning devices are used, then the manufacturing cost and complexity are reduced, but the flexibility to optimize for specific imaging conditions is limited
Solution Approach 1:
The exchangeable optical elements are designed with universal interfaces that accommodate standard patterning device dimensions while providing multiple functional options. Different optical elements can be exchanged to optimize for various imaging conditions (e.g., contact holes, different pattern types), allowing a single standard-sized patterning device to serve multiple optimization purposes through element exchange.
Solution Approach 2:
The system enables optimization of imaging parameters by exchanging optical elements with different properties (e.g., different pupil filters for different contrast requirements). This allows standard patterning devices to be used with optimized optical parameters for specific pattern types like contact holes, achieving customization without modifying the patterning device itself.
Data Source
AI summary
A lithographic apparatus has an assembly to exchange optical elements in a pupil plane of its projection system. The optical elements may be pupil filters and may conform to the physical dimensions specified for a reticle standard, e.g. having sides substantially equal to 5, 6 or 9 inches.