Photomask Variable Vernier Pattern for Semiconductor Lithography
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Solution Overview
Problem
Current patterning techniques for semiconductor devices, such as spacer patterning and extreme ultraviolet lithography, are costly and complex, making them unsuitable for mass production, and lack a reliable method for achieving small critical dimensions economically.
Innovation Solution
A photomask with a cell mask pattern and a vernier mask pattern that includes a variable mask pattern portion, which changes the pattern transferred based on exposure energy, allowing for different patterns to be formed using varying exposure energies, enabling efficient and economical formation of small critical dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If spacer patterning technology or mesh-type SPT technology is used to form patterns with smaller pitch, then the critical dimension is reduced, but the number of process steps increases and device fabrication costs increase
Solution Approach 1:
The photomask is designed to perform multiple functions: it contains both a cell mask pattern for forming cell patterns and a vernier mask pattern with variable mask pattern portions for forming vernier patterns and overlay measurement patterns. This multi-functional design allows a single photomask to replace what would otherwise require multiple separate masks and processes, thereby reducing the number of process steps while maintaining the ability to form patterns with small critical dimensions
Solution Approach 2:
The vernier mask pattern includes variable mask pattern portions that can selectively transfer different patterns depending on the magnitude of exposure energy. This dynamic characteristic allows the same photomask structure to produce different pattern outcomes based on exposure conditions, enabling flexible pattern formation and overlay measurement without requiring additional process steps
2Device complexity
If extreme ultraviolet lithography technology is used to form patterns with smaller pitch, then the process complexity is reduced, but reliable equipment for mass production has not been fully developed
Solution Approach 1:
The invention utilizes changes in exposure energy parameters to achieve different pattern transfer outcomes. By controlling the magnitude of exposure energy, the variable mask pattern portions selectively transfer patterns or not, enabling both vernier pattern formation and overlay measurement functions within a conventional lithography process framework that is reliable for mass production
3Ease of manufacture
If a single photomask is used to form multiple pattern layers with different shapes, then fabrication costs are reduced, but the photomask design complexity increases
Solution Approach 1:
The photomask is segmented into distinct functional regions: a cell mask pattern region for forming cell patterns and a vernier mask pattern region containing variable mask pattern portions for forming vernier patterns and overlay measurement patterns. This segmentation allows each region to perform its specific function independently while being integrated into a single photomask structure, managing design complexity through organized functional separation
Solution Approach 2:
The single photomask is designed with multi-functionality, incorporating both cell mask patterns and vernier mask patterns with variable mask pattern portions that can selectively transfer different patterns based on exposure energy. This universal design enables the photomask to form multiple pattern layers with different shapes while reducing fabrication costs by eliminating the need for multiple separate masks
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 allows for the formation of patterns with small critical dimensions efficiently and economically, facilitating mass production by using a single photomask to form multiple pattern layers with different shapes, thereby simplifying overlay measurement and reducing fabrication costs.
Implementation Method 1
A first cell photoresist pattern and a first vernier photoresist pattern are formed over the first hard mask layer by transferring a pattern of the photomask using first exposure energy
Data Source
AI summary
A semiconductor device includes a cell mask pattern disposed in a cell region of a mask substrate and a vernier mask pattern disposed in a vernier region of the mask substrate. The vernier mask pattern includes a variable mask pattern portion to transfer a different shape of pattern depending on the magnitude of exposure energy.