Photoluminescent Overlay Marks for Multi-Level Lithography Alignment
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Solution Overview
Problem
The semiconductor industry faces challenges in accurately measuring overlay errors due to asymmetric shapes of measurement structures, necessitating a new method for precise determination of overlay errors in lithography operations.
Innovation Solution
A method involving the formation of a photoluminescent layer on a semiconductor structure, including phosphor, quantum dots, or Gd2O2S:R materials, over a patterned substrate, with an intermediate layer and a patterned mask layer, allowing for optical signal detection and conversion to electrical signals for alignment assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional overlay measurement structures are used, then the measurement process is simple, but the measurement precision deteriorates due to asymmetric shapes and depth of field limitations
Solution Approach 1:
The patent introduces a vertical dimension by placing overlay marks at different elevations (first overlay mark on first substrate, second overlay mark on second substrate stacked thereon). This multi-elevation arrangement allows optical detection systems to measure overlay errors between layers separated by greater vertical distances, overcoming the depth of field limitations of conventional single-plane measurement methods.
Solution Approach 2:
The patent employs an optical detection system with excitation light sources and photodetectors as intermediaries to detect overlay alignment. The system uses optical signals to excite the overlay marks and detect their positions, converting physical alignment information into detectable optical signals that can be processed to determine overlay errors with high precision.
2Measurement precision
If overlay marks are placed at different elevations to overcome depth of field limitations, then measurement precision improves, but the device structure becomes more complex
Solution Approach 1:
The overlay marks are designed with photoluminescent properties that allow them to serve multiple functions: they act as alignment references for overlay measurement and simultaneously emit optical signals when excited. This multi-functionality reduces the need for separate indicator structures, simplifying the overall device architecture while maintaining high measurement precision across multiple elevations.
Solution Approach 2:
By stacking substrates with overlay marks at different elevations, the patent creates a three-dimensional measurement structure that overcomes the two-dimensional limitations of conventional overlay marks. This vertical stacking allows the measurement system to handle greater vertical separations between layers while maintaining alignment detection accuracy.
3Measurement precision
If photoluminescent materials are used in overlay marks, then detection sensitivity improves, but the manufacturing process becomes more complex
Solution Approach 1:
The patent utilizes photoluminescent materials with specific emission characteristics that can be excited by standard optical sources. By selecting materials with appropriate photoluminescent properties, the system achieves enhanced detection sensitivity without requiring complex manufacturing processes, as the photoluminescent layers can be deposited using conventional thin-film deposition techniques.
Solution Approach 2:
The photoluminescent materials act as intermediaries that convert incident optical excitation signals into detectable emission signals. This conversion process enhances the detection sensitivity of the overlay marks, allowing for more precise alignment measurements while using standard optical detection equipment and manufacturing processes.
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 approach enables precise alignment detection between overlay marks at different elevations, improving the accuracy of overlay error measurement beyond the depth of field limitations, facilitating more precise semiconductor manufacturing.
Implementation Method 1
forming a photoluminescent layer on the first pattern
Implementation Method 2
an optical device, configured to emit a radiation to excite a photoluminescent material of an overlay mark
Implementation Method 3
an optical filter, configured to receive and filter a radiation emitted from the photoluminescent material
Implementation Method 4
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 method of manufacturing a 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 and 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.