Reflector Pressure Channels for Fast Lithography Overlay Correction
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Solution Overview
Problem
Existing lithographic apparatuses struggle to correct higher order overlay errors and perform fast, high-frequency deformations due to the slow thermal response of large, bulky EUV reflectors, limiting their ability to align patterns accurately across multiple substrate layers.
Innovation Solution
A lithographic apparatus with a reflector featuring channels for fluid conveyance, controlled by a pressure-adjusting system, allows for rapid deformation of the reflective surface to correct higher order optical errors and align patterns with precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal deformation method is used to control overlay, then overlay control capability is improved, but response speed deteriorates due to slow thermal setting time of large reflectors
Solution Approach 1:
The patent applies pneumatic pressure through channels formed in the reflector body to deform the reflective surface. This hydraulic/pneumatic approach enables fast response overlay corrections by using fluid pressure instead of thermal methods, directly addressing the slow response time issue while maintaining overlay control capability.
Solution Approach 2:
The patent changes the physical parameter used for deformation from temperature (thermal method) to pressure (pneumatic method). By applying pressure through controlled channels in the reflector body, the system achieves rapid deformation of the reflective surface without the thermal inertia limitations, thus improving response speed while maintaining manufacturing precision.
2Manufacturing precision
If reflector size is increased to reduce lower order overlay errors, then overlay control for lower order errors is improved, but ability to perform fast high frequency deformations deteriorates
Solution Approach 1:
The patent incorporates channels within the reflector body that allow pneumatic pressure to be applied directly to specific regions of the reflective surface. This enables localized, high-frequency deformations even in large reflectors, overcoming the limitation that larger reflectors are too slow to respond at high frequencies while maintaining the ability to correct lower order overlay errors.
Solution Approach 2:
The patent segments the reflector structure by incorporating internal channels that can be independently pressurized. This segmentation allows different regions of the reflective surface to be deformed independently and at high frequencies, enabling the large reflector to perform fast corrections while maintaining overall shape control for lower order errors.
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
The apparatus achieves fast, high spatial-frequency overlay corrections, reducing higher order polynomial deformation profiles and improving pattern alignment accuracy by applying deformations on the nanometer scale.
Implementation Method 1
a controller configured to adjust a pressure of the fluid in the channel to control a deformation of the reflective surface
Data Source
AI summary
A lithographic apparatus including a reflector for reflecting radiation. The reflector has a body, a reflective surface arranged on the body, and a channel formed in the body for conveying a fluid. The lithographic apparatus includes a controller configured to adjust a pressure of the fluid in the channel to control a deformation of the reflective surface and thereby control an overlay of the lithographic apparatus.