Deformable Plate Magnification Control in Lithography
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Solution Overview
Problem
Microlithographic projection systems face challenges in maintaining precise magnification control while minimizing distortion and wavefront aberrations, especially in telecentric systems, due to variations in operating conditions such as temperature and pressure, which complicates the stitching and registration of patterns for semiconductor device manufacturing.
Innovation Solution
A magnification adjustable lithographic projection system utilizing a deformable plate preloaded to an initially curved condition, with an actuator adjusting its curvature to compensate for magnification changes, maintaining telecentricity and minimizing distortion by varying the curvature within a predetermined range while keeping the plate under constant loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If component shifts are made in object space to control magnification, then magnification is adjusted, but image distortion and wavefront aberrations increase
Solution Approach 1:
A deformable plate is introduced as an intermediary element in the optical path. This plate can be deformed to change its optical power, thereby adjusting magnification without requiring component shifts that would cause distortion. The deformable plate acts as a mediator between the fixed optical components and the magnification control requirement.
Solution Approach 2:
The optical power of the deformable plate is changed by varying its physical shape (curvature). By controlling the degree of deformation of the plate, the magnification can be adjusted continuously without moving other optical components, thus avoiding the introduction of distortion and aberrations.
2Manufacturing precision
If corrective optics with specially shaped surfaces are used to adjust magnification and distortion, then magnification control is achieved, but device complexity increases
Solution Approach 1:
Instead of using fixed corrective optics with specially shaped surfaces, a deformable plate is used that can dynamically change its shape and optical power. This dynamic approach allows a single element to perform the function of multiple fixed corrective elements, simplifying the overall optical system while maintaining magnification and distortion control.
Solution Approach 2:
The deformable plate serves multiple functions: it controls magnification, corrects distortion, and maintains wavefront quality. A single multi-functional element replaces what would traditionally require multiple specialized optical components, thereby reducing system complexity.
3Stability of the object's composition
If telecentricity is maintained in image space, then magnification stability is improved, but magnification adjustment becomes difficult
Solution Approach 1:
The deformable plate is positioned in a telecentric region of the optical system, where it can modify magnification without disrupting the telecentric condition. The plate acts as an intermediary that allows magnification adjustment while the rest of the system maintains its telecentric configuration, ensuring both stability and adjustability.
Solution Approach 2:
The deformable plate introduces local optical power changes at a specific location in the telecentric region, rather than requiring global changes to the optical system. This localized modification allows magnification adjustment while preserving the telecentric properties of the overall system.
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 allows for precise control of magnification in both orthogonal directions with minimal impact on aberrations, enabling accurate pattern registration and matching of optical systems, thus improving the reliability and efficiency of microlithographic processes.
Implementation Method 1
A deformable plate is mounted within a telecentric object or image space of a projection system for adjusting a magnification of the projection system. The plate is preloaded into an initially curved condition and subsequent loading varies the curvature of the plate within a predetermined range.
Data Source
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AI summary
In a lithographic projection system, a corrective optic in the form of one or more deformable plates is mounted within telecentric image or object space for making one-dimensional or two-dimensional adjustments to magnification. The deformable plate, which can be initially bent under the influence of a preload, contributes weak magnification power that influences the magnification of the projection system by changing the effective focal length in object or image space. An actuator adjusts the amount of curvature through which the deformable plate is bent for regulating the amount of magnification imparted by the deformable plate.