Photomask Binding and Separation Patterns for Lithography Margin
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Solution Overview
Problem
Current semiconductor manufacturing techniques face challenges in forming fine features smaller than the wavelength of exposure light due to proximity effects, leading to potential short circuits and defects, especially when using super-resolution techniques for conductive line ends that face each other or are adjacent, which can result in reduced lithography margins and increased defect rates.
Innovation Solution
A method involving the use of two photomasks with specific binding and separation patterns, where the first photomask includes binding patterns to connect line ends and the second photomask has separation patterns that ensure a sufficient lithography margin by forming transparent patterns with areas larger than a predetermined threshold, allowing for accurate transfer of reticle patterns to the semiconductor device without altering optical conditions between exposure steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If super-resolution techniques are used to enhance resolution for fine features smaller than the wavelength of exposure light, then resolution is improved, but lithography margin is reduced and short circuits may occur
Solution Approach 1:
The patent segments the patterning process into multiple exposing steps, each handling different portions of the pattern. The first exposing step forms a preliminary pattern with sufficient lithography margin, while subsequent steps add fine features. This segmentation allows resolution enhancement without compromising the lithography margin of critical features.
Solution Approach 2:
The patent performs preliminary patterning actions in earlier exposing steps to establish a foundation pattern with adequate lithography margin. Subsequent exposing steps then build upon this foundation to add finer details, ensuring that critical features are established before attempting to form smaller features that require super-resolution techniques.
2Manufacturing precision
If two exposing steps with different reticles and optical conditions are performed to pattern gate electrodes, then pattern shape accuracy is improved, but lithography margin is reduced and defects increase
Solution Approach 1:
The patent maintains consistent optical conditions across all exposing steps, creating an equipotential environment where the same exposure parameters are applied throughout the multi-step process. This consistency ensures that lithography margins are preserved while still achieving accurate pattern shapes through the cumulative effect of multiple exposures with different reticles.
3Length of moving object
If features smaller than the wavelength of exposure light are formed, then miniaturization is achieved, but proximity effects increase causing pattern differences
Solution Approach 1:
The patent applies local quality by treating different regions of the pattern differently across multiple exposing steps. Areas with fine features smaller than the wavelength are targeted in specific steps with optimized reticle designs, while other areas are formed in earlier steps. This localized approach allows miniaturization in critical regions without allowing proximity effects to degrade overall pattern accuracy.
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 reduces defects in resolution and maintains high accuracy in semiconductor device manufacturing, enabling the creation of smaller feature sizes and improved memory density without short circuits, while simplifying the process and increasing throughput by maintaining consistent optical conditions across exposure steps.
Implementation Method 1
patterning the first photoresist film using a first photomask; patterning the second photoresist film using a second photomask
Data Source
AI summary
A method for designing a photomask pattern is provided. First, all line ends of object patterns are determined with reference to layout data. Then, object patterns, front edge portions, and joints, which are aligned on the same line extending along the Y-axis, are connected to form first reticle data. Reticle pattern data having data representing binding portions serving as light blocking portions is formed. The front edge portions being adjacent to each other and aligned in the X-axis are connected and adjacent joints being aligned in the same manner as the front edge portions are also connected to form second reticle data. Then, portions are provided at central regions between the binding portions so as to connect the adjacent binding portions including the front edge portions and the joints. Then, reticle data having data representing the binding portions serving as transparent patterns is formed.