Lithography Wave-Front Control via Phase Shifter
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Solution Overview
Problem
Conventional photolithography systems face issues with lens aberrations causing deviations in feature dimensions and locations on semiconductor wafers, leading to inferior or defective devices, and require optimization that cannot be achieved with physical changes to the lens system.
Innovation Solution
An illumination system with a phase shifter and controller that adjusts the phase of light passing through different zones of the projection lens assembly, allowing for precise adjustment of pattern dimensions and locations without physical alterations to the lens system, using Zernike polynomial coefficients and wave-front maps to model and correct deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If lens aberrations are present in the photolithography system, then the lens system can be simple and physically unchanged, but the printed features deviate from designed dimensions and locations
Solution Approach 1:
The patent introduces a phase shifter as an intermediary component between the illumination source and the projection lens assembly. This phase shifter modulates the wavefront of light before it enters the lens system, enabling correction of lens aberrations without modifying the lens elements themselves. The phase shifter acts as a mediator that compensates for optical imperfections through wavefront control
Solution Approach 2:
The patent changes the phase parameter of light waves across different zones of the illumination system. By applying different phase shifts to different regions of the illumination aperture, the system dynamically adjusts the wavefront to counteract lens aberrations, thereby improving feature precision without physical lens modifications
2Manufacturing precision
If physical changes are made to the lens system to correct aberrations, then feature precision can be improved, but the lens system requires complex modifications and retargeting
Solution Approach 1:
The patent replaces mechanical lens modifications with an optical control mechanism. Instead of physically altering lens elements, coatings, or structures, the system uses a phase shifter to modulate light waves, substituting mechanical intervention with optical field control to achieve the same correction goal
Solution Approach 2:
The patent creates a virtual model of the lens aberrations and their correction requirements. By modeling the wavefront distortions and calculating appropriate phase compensation patterns, the system determines the precise phase shifts needed without physically testing or modifying the lens system
3Device complexity
If lens aberrations cause deviations, then the lens system can remain simple and unchanged, but device quality becomes inferior or defective
Solution Approach 1:
The patent applies preliminary wavefront correction by introducing the phase shifter before the light enters the projection lens assembly. The phase shifter pre-compensates for known lens aberrations by adjusting the illumination wavefront in advance, preventing deviations before they occur during the exposure process
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
Enables precise control over feature dimensions and locations on semiconductor wafers, reducing deviations caused by lens aberrations and optimizing pattern placement, resulting in improved device quality and process efficiency.
Implementation Method 1
an illumination system with a phase shifter and controller that adjusts the phase of light passing through different zones of the projection lens assembly
Implementation Method 2
using Zernike polynomial coefficients and wave-front maps to model and correct deviations
Data Source
AI summary
Some embodiments include system and methods to obtain information for adjusting variations in features formed on a substrate of a semiconductor device. Such methods can include determining a first pupil in an illumination system used to form a first feature, and determining a second pupil used to form a second feature. The methods can also include determining a pupil portion belonging to only one of the pupils, and generating a modified pupil portion from the pupil portion. Information associated with the modified pupil portion can be obtained for controlling a portion of a projection lens assembly of an illumination system. Other embodiments are described.