Lithographic Measurement System Multi-Reflection Precision
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Solution Overview
Problem
Conventional lithographic apparatuses face challenges in achieving high precision due to increasing circuit pattern size requirements, necessitating an improved measurement system for accurate substrate positioning and deformation control.
Innovation Solution
A lithographic apparatus with a measurement system that includes a substrate table, a projection system, a measurement radiation system with reflectors, and a detector to measure the wavelength of a radiation beam transmitted through the reflectors, allowing for precise determination of the distance between reflectors and deformation control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement systems are used in lithographic apparatus, then the apparatus can operate with simpler measurement components, but the measurement precision and positioning accuracy deteriorate due to increasing circuit pattern size requirements
Solution Approach 1:
The patent transitions from conventional single-pass measurement methods to a multi-pass measurement system where the measurement beam reflects multiple times between reflectors. This dimensional change in the measurement approach (from direct to multi-reflection path) enables enhanced precision by accumulating measurement data over multiple interactions with the measurement target, thereby improving measurement precision without proportionally increasing overall system complexity
Solution Approach 2:
The patent introduces reflectors as intermediary elements between the measurement beam and the target. These reflectors serve as mediators that enable the measurement beam to interact with the measurement target multiple times, effectively amplifying the measurement signal and improving precision. The reflectors act as intermediate components that facilitate enhanced measurement capability without requiring direct modification of the core measurement system
2Manufacturing precision
If the circuit pattern size is decreased to increase resolution, then the resolution capability improves, but the precision requirement within the apparatus increases
Solution Approach 1:
The patent implements a feedback mechanism where the measurement system continuously monitors the position and deformation of substrates and patterning devices. The measurement beam reflects multiple times between reflectors attached to these components, providing amplified feedback signals that enable real-time detection of positional changes and deformations. This feedback is used to adjust and maintain manufacturing precision at the required level for decreased circuit pattern sizes
Solution Approach 2:
The multi-reflection measurement approach adds a temporal dimension to the measurement process, allowing accumulation of measurement information over multiple beam reflections. This dimensional enhancement in measurement methodology provides the increased precision required to support smaller circuit pattern sizes and higher resolution manufacturing
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 enhances the precision and accuracy of substrate positioning and deformation measurement, enabling improved resolution and stability in lithographic processes, particularly in the manufacturing of integrated circuits.
Implementation Method 1
at least two reflectors to reflect a significant portion of the measurement beam between the reflectors
Implementation Method 2
detecting a wavelength of a beam transmitted through one of the reflectors
Data Source
AI summary
A lithographic apparatus includes a support constructed to support a patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam; a substrate table constructed to hold a substrate; a projection system configured to project the patterned radiation beam onto a target portion of the substrate, and a measurement system with a measurement radiation system to provide a measurement beam of radiation, at least two reflectors to reflect a portion of the measurement beam between the reflectors; and a detector to detect a wavelength of at least a portion of the measurement beam transmitted through one of the reflectors.