Photoluminescent Overlay Mark Structure for Deep-Focus Alignment
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Solution Overview
Problem
The semiconductor industry faces challenges in accurately measuring overlay errors in photoresist patterns and underlying patterns due to asymmetric shapes of measurement structures, necessitating a more precise method for overlay error detection.
Innovation Solution
A semiconductor structure is developed with a photoluminescent material layer that allows for precise alignment detection by emitting optical signals, which are converted into electrical signals for accurate alignment of patterns, using a system comprising an optical device, filter, and detector to process these signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional detection methods are used for overlay marks, then the measurement process is simple, but the measurement precision deteriorates due to asymmetric shapes of measurement structures and inability to detect marks beyond depth of focus
Solution Approach 1:
The patent introduces an optical intermediary substance (photoluminescent material) between the overlay mark and the detector. This material absorbs light at one wavelength and emits it at a different wavelength, enabling the detection system to see through intermediate layers and achieve precise alignment measurement even when the distance exceeds the detector's depth of focus.
Solution Approach 2:
The patent replaces traditional direct optical detection with a photoluminescence-based detection system. Instead of using conventional optical paths that are limited by depth of focus, the system uses photoluminescent materials to convert optical signals, enabling detection of overlay marks at greater distances with improved precision.
2Ease of manufacture
If the distance between overlay mark layers is increased to accommodate manufacturing processes, then the ease of manufacture improves, but the measurement precision deteriorates because the distance exceeds the detector's depth of focus
Solution Approach 1:
The photoluminescent material acts as an intermediary that enables optical signal transmission across larger distances. By placing this material in the intermediate layer between overlay marks, the system maintains measurement precision even when the physical distance between layers is increased to accommodate manufacturing requirements.
Solution Approach 2:
The patent changes the optical parameters of the intermediate layer by introducing photoluminescent material with specific emission wavelengths. This allows the detection system to detect overlay marks at greater distances by utilizing the photoluminescent emission rather than direct reflection, effectively extending the measurable range without sacrificing 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
This method enables precise alignment of patterns, overcoming the limitations of traditional detection methods by allowing for clear detection of overlay marks even when the distance between layers exceeds the detector's depth of focus, thereby improving the accuracy of semiconductor fabrication.
Implementation Method 1
The alignment equipment comprises: a stage, configured to support a semiconductor structure; an optical device, configured to emit a radiation to excite a photoluminescent material of an overlay mark
Implementation Method 2
an optical filter, configured to receive and filter the radiation emitted from the photoluminescent material
Implementation Method 3
an optical detector, configured to convert an optical signal filtered by the optical filter to an electrical signal
Data Source
AI summary
The present disclosure provides a semiconductor structure, a method of manufacturing the semiconductor structure and a system for manufacturing the semiconductor structure. The method includes several operations. A substrate including a device region and a scribe line region is provided. A first layer is formed over the substrate. A first photoluminescent layer is formed over the first layer in the scribe line region. The first layer and the first photoluminescent layer are patterned to form a first pattern in the scribe line region. A first patterned mask layer is formed over a second layer. An alignment of the first patterned mask layer with the first pattern is detected. A pattern of the first patterned mask layer is transferred to the second layer to form a second pattern in the scribe line region.