Alignment Mark Layout for High-Precision Wafer Overlay
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Solution Overview
Problem
Existing lithography processes face challenges in achieving high overlay accuracy between multilayered circuit patterns on substrates, leading to defective semiconductor devices due to poor wafer alignment, and existing alignment detection systems are costly and have design limitations.
Innovation Solution
A layout method and exposure apparatus with fixed and movable alignment detection systems that allow for variable spacing between detection centers, enabling efficient detection of multiple alignment marks using a diffraction light interference method, and a measurement device to calculate precise alignment and scaling of shot areas on a substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple alignment detection systems are used to detect more alignment marks, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The wafer surface is divided into multiple shot areas, each containing alignment marks that can be detected by alignment detection systems. This segmentation allows the system to process alignment information from different regions independently, improving overall measurement precision without requiring a single complex detection system to cover the entire wafer.
Solution Approach 2:
Multiple alignment detection systems are combined to detect alignment marks across different shot areas simultaneously. By merging the detection capabilities of multiple systems, the patent achieves higher measurement precision for wafer alignment while managing device complexity through coordinated operation of the combined systems.
2Measurement precision
If the number of sample shot areas is increased to improve alignment accuracy, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The wafer is divided into multiple shot areas with alignment marks distributed across them. By segmenting the alignment measurement task across multiple shot areas, the system can achieve high measurement precision without requiring excessive sampling, thus maintaining productivity through efficient use of detection resources.
Solution Approach 2:
Instead of measuring all shot areas exhaustively, the patent uses a statistically determined number of sample shot areas that provides sufficient alignment accuracy. This partial action approach maintains productivity while achieving the required measurement precision through optimized sampling strategies.
3Adaptability or versatility
If movable alignment detection systems are used to cope with various shot maps, then adaptability is improved, but device complexity increases
Solution Approach 1:
The alignment detection systems are designed with movable components that can be repositioned to accommodate different shot maps and alignment mark arrangements. This dynamic capability allows the system to adapt to various configurations while maintaining manageable device complexity through modular design and controlled movement mechanisms.
Solution Approach 2:
The system can change operational parameters such as detection field position, spacing between detection systems, and sampling patterns to adapt to different shot maps. By adjusting these parameters rather than redesigning the entire system, the patent achieves high adaptability while controlling device complexity.
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
Enhances overlay accuracy and reduces costs by allowing for high-precision alignment and efficient detection of alignment marks, improving the production of semiconductor devices.
Implementation Method 1
enabling efficient detection of multiple alignment marks using a diffraction light interference method
Data Source
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AI summary
On a substrate conforming to a layout method for a plurality of marks for detection using a plurality of mark detection systems (AL1, AL21 to AL24) of which the detection centers are arranged at a predetermined spacing along an X-axis direction, a plurality of shot areas Si (i=1, 2, ...) are formed in both an X-axis direction and a Y-axis direction orthogonal thereto in an XY plane, and sets including at least two marks (WMj) (j=1, 2, 3, 4, 5) separated in the X-axis direction are repeatedly arranged along the X-axis direction at spacing of a length (w) in the X-axis-direction of each shot area (Si), and the marks belonging to each set are separated from each other in the X-axis direction by a spacing determined based arrangement in the X-axis direction of the plurality of mark detection systems (AL1, AL21 to AL24) and the length (w). It is thereby possible to reliably detect a plurality of marks on a substrate using a plurality of mark detection systems.