Deformable Lenses in Micro Lithography Projection Objectives
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Solution Overview
Problem
Microlithography projection objectives face challenges in maintaining imaging quality due to aberrations caused by material ageing and temporary heating, which conventional actively deformable lenses struggle to effectively correct without inducing other image defects.
Innovation Solution
The method involves selecting at least two actively deformable lenses within the projection objective, allowing for independent correction of primary and higher-order image defects by varying their deformation profiles, shapes, and positions to compensate for complex wavefront aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single actively deformable lens is used to correct image defects, then the correction capability is limited to simple wavefront aberration profiles, but the device complexity is reduced
Solution Approach 1:
The correction system is segmented into multiple independently controllable deformable lens elements rather than using a single deformable lens. Each lens element can be deformed independently to address different aspects of wavefront aberrations, thereby increasing correction capability while managing system complexity through modular design
Solution Approach 2:
Multiple deformable lens elements serve universal correction functions across different Zernike orders and aberration types. The system achieves multi-functionality by using the same basic component type (deformable lens) in multiple locations, where each instance can be independently controlled to address various aberration modes
2Manufacturing precision
If multiple lenses are actively deformed to correct complex wavefront aberrations, then imaging quality is improved, but the device complexity increases
Solution Approach 1:
The optical system is divided into multiple zones with independently deformable lens elements, allowing complex wavefront aberrations to be corrected by coordinating the deformation of multiple segments rather than requiring a single highly complex deformable lens
Solution Approach 2:
The lens elements are made dynamically deformable with independent control, allowing the system to adapt to different aberration conditions by adjusting the deformation state of each lens element in real-time, thereby improving imaging quality without permanently increasing structural complexity
3Reliability
If conventional actively deformable lenses are used to correct image defects, then some aberrations are corrected, but other image defects are induced
Solution Approach 1:
By segmenting the correction function across multiple lens elements, each element can be optimized to correct specific aberration types without introducing the side effects that a single deformable lens would impose on other parts of the wavefront
Solution Approach 2:
Each deformable lens element is independently controlled to provide localized correction for specific regions of the wavefront or specific Zernike orders, allowing precise correction of target aberrations while minimizing interference with other image quality parameters
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 approach enables improved imaging properties by breaking linear dependencies between Zernike orders, allowing for more effective correction of wavefront aberrations with a simpler setup, reducing the overall outlay and enhancing the projection objective's ability to handle field-dependent and constant-field components.
Implementation Method 1
a first manipulator for actively deforming a first lens... the first lens being deformed for at least partially correcting an image defect
Data Source
AI summary
The invention relates to a method for improving the imaging properties of a micro lithography projection objective, wherein the projection objective has a plurality of lenses between an object plane and an image plane, a first lens of the plurality of lenses being assigned a first manipulator (ml, Mn) for actively deforming the lens, the first lens being deformed for at least partially correcting an aberration, at least one second lens of the plurality of lenses furthermore being assigned at least one second manipulator, and the second lens being deformed in addition to the first lens. Furthermore, a method is described for selecting at least one lens of a plurality of lenses of a projection objective as actively deformable element, and a projection objective.