3D Overlay Mark Layout for Multi-Layer Alignment Measurement
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Solution Overview
Problem
Existing overlay mark methods for semiconductor integrated circuits are inefficient in measuring alignment accuracy between multiple layers, particularly at small dimensions, leading to increased area costs and time-consuming data collection, and are not adequately focused on the directional deviations relevant for each layer alignment.
Innovation Solution
The introduction of an overlay mark system with features extending in both X and Y directions, allowing for simultaneous measurement of X and Y directional deviations between layers on the same substrate area, reducing area cost and time by focusing on the most relevant deviations for each layer alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional overlay mark methods are used to measure alignment accuracy between multiple layers, then measurement capability is provided, but area cost increases and data collection time is excessive
Solution Approach 1:
The overlay mark is segmented into distinct features at different heights (first feature at first height, second feature at second height, third feature at third height), allowing separate measurement of X and Y directional deviations. This segmentation enables focused data collection on relevant deviations for each layer alignment, reducing overall data collection time while maintaining measurement precision.
Solution Approach 2:
The invention introduces vertical dimension (height) as an additional degree of freedom by positioning features at different heights above the substrate. This three-dimensional arrangement allows simultaneous encoding of multiple alignment parameters (X deviation, Y deviation) in a compact structure, reducing the area required for overlay marks while increasing measurement capability.
2Measurement precision
If traditional overlay mark methods are used to measure alignment accuracy between multiple layers, then measurement capability is provided, but area cost increases
Solution Approach 1:
By utilizing the vertical dimension to position features at different heights, the invention encodes multiple alignment parameters in a compact three-dimensional structure. This reduces the horizontal area required for overlay marks while maintaining comprehensive measurement capability for multi-layer alignment.
Solution Approach 2:
The overlay mark structure serves multiple functions simultaneously: the first feature measures X directional deviation, the second feature measures Y directional deviation, and the third feature provides additional alignment reference. This multi-functionality in a single compact structure reduces the total area required compared to separate measurement features.
3Measurement precision
If existing overlay marks are used for small dimensional devices, then alignment measurement is provided, but measurement accuracy is insufficient
Solution Approach 1:
The overlay mark is segmented into distinct features at different heights, with each feature optimized for measuring specific directional deviations. This segmentation allows for more precise measurement of overlay errors in small dimensional devices by separating X and Y deviation measurements into distinct structural elements.
Solution Approach 2:
By adding vertical separation between measurement features, the invention enhances measurement sensitivity and precision for small dimensional devices. The height differences create distinct optical paths and measurement zones that improve the accuracy of overlay error detection in scaled-down device geometries.
Data Source
AI summary
An overlay mark includes a first feature extending in an X-direction, wherein the first feature is a first distance from a substrate. The overlay mark further includes a second feature extending in a Y-direction perpendicular to the X-direction, wherein the second feature is a second distance from the substrate, and the second distance is different from the first distance, wherein at least one of the first feature or the second feature comprises a conductive material. The overlay mark further includes a third feature extending in the X-direction and the Y-direction, wherein the third feature is a third distance from the substrate, and the third distance is different from the first distance and the second distance. The first distance, the second distance and the third distance from the substrate are along a Z-direction perpendicular to both the X-direction and the Y-direction.