Backside Alignment Using Single Infrared Illumination
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Solution Overview
Problem
Conventional backside alignment apparatuses for semiconductor lithography are complex and costly to assemble, with multiple illumination devices required for each alignment mark, leading to high processing costs and poor process adaptation.
Innovation Solution
A backside alignment apparatus using a single infrared illumination apparatus and imaging apparatus, with a workpiece stage capable of moving in multiple degrees of freedom, allowing for alignment of multiple marks through a base aperture and reducing the complexity of the structure design and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple illumination devices are used for each backside alignment mark, then alignment precision is improved, but device complexity and assembly cost increase significantly
Solution Approach 1:
The patent combines multiple illumination devices into a single illumination device that can illuminate multiple backside alignment marks simultaneously. This is achieved by designing an illumination system with a unified light source and optical path that covers the entire array of alignment marks, thereby reducing device complexity and assembly cost while maintaining alignment precision through the use of a single integrated illumination system
Solution Approach 2:
The illumination device is designed to perform multiple functions by illuminating all backside alignment marks with a single device. The universal illumination system can serve all alignment marks across different positions and orientations, eliminating the need for separate illumination devices for each mark and significantly simplifying the overall system configuration
2Adaptability or versatility
If multiple illumination devices are arranged under the wafer stage, then alignment coverage is improved, but wafer stage structure complexity and processing cost increase
Solution Approach 1:
The patent merges multiple illumination functions into a single illumination device located under the wafer stage. This unified device uses a shared optical path and light source to illuminate all alignment marks, thereby achieving comprehensive alignment coverage without increasing wafer stage structure complexity or processing cost
Solution Approach 2:
The illumination system is designed to illuminate alignment marks in multiple dimensions simultaneously through a single device. By using an extended illumination field and appropriate optical design, the system can cover alignment marks across the entire wafer surface area, achieving multi-dimensional coverage without adding multiple physical devices
3Measurement precision
If each backside alignment mark requires a dedicated illumination device, then alignment accuracy is improved, but process adaptation deteriorates
Solution Approach 1:
The single illumination device is designed with universal capability to illuminate any backside alignment mark on the wafer by adjusting the optical path and illumination field. This universal design maintains high alignment accuracy for all marks while significantly improving process adaptation, as the system can accommodate different wafer sizes, mark positions, and processing requirements without requiring additional devices
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 simplifies the configuration and reduces processing complexities, lowering development costs and improving process adaptation by using a single set of radiation sources and imaging apparatus for both reference plate and backside alignment marks.
Implementation Method 1
an infrared light source (10) configured to provide infrared light
Implementation Method 2
an imaging lens group (31) aligned with the base aperture, the image of the illuminated reference plate alignment mark or any one of the at least one illuminated backside alignment mark successively passing through the imaging lens group
Data Source
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AI summary
A backside alignment apparatus and method for determining a position relationship between a substrate (6) and a workpiece stage (24). The backside alignment apparatus includes: an illumination apparatus (1) for emanating infrared light; a workpiece stage assembly (2) for supporting and moving the substrate (6); an imaging apparatus (3) for detecting alignment marks and calculating positions of the alignment marks, the alignment marks including a reference plate alignment mark (41) and a backside alignment mark (20); and a reference plate assembly (4) for setting up a relationship between position coordinates of the imaging apparatus (3) and the workpiece stage assembly (2). The illumination apparatus (1) and the imaging apparatus (3) are able to illuminate and align different alignment marks using only one set of illumination apparatus.