Lithography Optical Module Alignment Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithography systems face challenges in ensuring that the image plane projected is parallel to and in focus on the substrate, leading to incorrect patterning and defects like mura, which is difficult and resource-intensive to correct.
Innovation Solution
A method involving a spatial light modulator and beam splitter in the optical module to direct light beams towards reflective and patterned surfaces, taking images, and determining tip, tilt, and vertical corrections to align the optical module optimally, using both brightfield and darkfield illumination techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the image plane is not properly aligned or focused, then patterning accuracy deteriorates causing defects like mura, but manual correction is difficult and time-consuming
Solution Approach 1:
The system performs self-diagnosis and self-correction by automatically measuring alignment and focus parameters using test patterns and computational algorithms, then adjusting optical components without manual intervention. This eliminates the need for time-consuming manual correction while maintaining high patterning accuracy.
Solution Approach 2:
The system performs preliminary alignment and focus measurements using test substrates with specific patterns before actual production patterning. This preliminary characterization allows the system to pre-determine correction parameters, ensuring accurate patterning from the start and avoiding subsequent time-consuming adjustments.
2Manufacturing precision
If traditional alignment and focus methods are used, then manufacturing precision can be maintained, but resource consumption and operational complexity increase
Solution Approach 1:
The system uses a single integrated optical path and camera system to perform multiple functions: measuring alignment (tip/tilt), measuring focus (vertical position), and characterizing optical aberrations. This multi-functional approach maintains manufacturing precision while reducing the need for separate correction systems and procedures.
Solution Approach 2:
The system measures and corrects alignment and focus by determining optimal parameter values (tip correction, tilt correction, vertical correction) through automated image analysis of test patterns. This parameter-based correction approach simplifies the system compared to mechanical adjustment mechanisms while maintaining precision.
3Measurement precision
If multiple measurement approaches are used to ensure accuracy, then measurement precision improves, but the number of substrates and resources required increases
Solution Approach 1:
The measurement process is segmented into distinct functional components: brightfield imaging for certain alignment parameters, darkfield imaging for other parameters, and computational analysis. This segmentation allows each measurement type to be optimized independently while reducing overall substrate requirements compared to using a single comprehensive measurement method.
Solution Approach 2:
The system uses periodic illumination modes (brightfield and darkfield) alternately to measure different aspects of alignment and focus. This periodic measurement approach extracts multiple measurement dimensions from sequential single-substrate measurements, reducing the need for multiple substrates while maintaining measurement precision.
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
Facilitates quick and effective calibration of the optical module to achieve a parallel and in-focus image plane, reducing mura and operational costs, and improving patterning accuracy and throughput.
Implementation Method 1
directing first light beams toward a reflective surface of a first substrate
Implementation Method 2
collecting the second light beams that scatter off of the patterned surface
Implementation Method 3
collecting the first light beams that reflect off of the reflective surface through at least an objective lens of the optical module
Implementation Method 4
taking a plurality of first images, using the camera, of the first light beams directed toward the camera
Data Source
AI summary
Aspects of the present disclosure relate to methods and apparatus for correcting lithography systems. In one implementation, a method of operating a lithography system includes directing first light beams toward a reflective surface of a first substrate using an optical module. The method includes directing the first light beams collected through at least an objective lens toward a camera, and taking a plurality of first images of the first light beams. The method includes directing second light beams at an oblique angle toward a patterned surface of a second substrate using an illumination source disposed below the objective lens. The method includes directing the second light beams collected through at least an objective lens toward a camera, and taking a plurality of second images of the second light beams. The method includes determining a tip correction, a tilt correction, and an optimal vertical position for the optical module.