Cut Pattern Pitch Relaxation With Ion-Expanded Cut Margins
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Solution Overview
Problem
The increasing density of features in integrated circuit patterns makes it difficult to use a single photomask for forming cut patterns, leading to increased process errors and fabrication costs, especially when using immersion lithography or extreme ultraviolet (EUV) lithography.
Innovation Solution
A pitch relaxation process is employed, where some cut features are shifted to increase the distance between them, allowing these features to be printed using a single photomask. Subsequently, ion implantation is used to enlarge the cut features and recover the cut margin, ensuring a sufficient cut window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple photomasks are used to form cut patterns at high feature density, then the cut pattern can be formed, but fabrication costs and process errors increase
Solution Approach 1:
The patent applies preliminary action by performing pitch relaxation before photomask formation. Cut features are shifted to relaxed pitches in the main pattern formation step, ensuring that a single photomask can accommodate all features without requiring multiple masks. This preliminary arrangement prevents the need for complex multi-mask processes while maintaining pattern accuracy.
Solution Approach 2:
The patent changes the pitch parameter of cut features through pitch relaxation. By adjusting the spacing between cut features to relaxed pitches that exceed the lithography process minimum pitch requirements, the system enables single-mask fabrication. This parameter modification resolves the contradiction between pattern density and manufacturability.
2Ease of manufacture
If pitch relaxation is applied to enable single photomask fabrication, then fabrication costs decrease, but cut margin is reduced
Solution Approach 1:
The patent performs preliminary ion implantation enlargement of cut features before the cut process. By pre-enlarging the cut features through ion implantation, sufficient cut margin is maintained even after pitch relaxation shifts the features. This preliminary compensation ensures that the relaxed pitch design does not compromise the cut process window.
Solution Approach 2:
The patent changes the size parameter of cut features through ion implantation. The ion implantation process enlarges the cut features from their relaxed pitch dimensions to the required final dimensions, ensuring adequate cut margin. This parameter transformation allows the system to benefit from relaxed pitch spacing while maintaining sufficient cut window for manufacturing.
3Manufacturing precision
If ion implantation is used to enlarge cut features, then cut margin is recovered, but process complexity increases
Solution Approach 1:
The patent merges the ion implantation enlargement step with the existing pitch relaxation and cut process flow. By integrating the ion implantation step into the overall fabrication sequence, the system recovers cut margin without creating entirely separate process chains. This merging approach minimizes the increase in process complexity while achieving the desired cut feature dimensions.
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 reduces fabrication costs and processing errors by enabling the use of a single photomask for cut pattern formation and improving the cut process window through ion implantation.
Implementation Method 1
ion implantation is used to enlarge the cut features and recover the cut margin
Implementation Method 2
performing at least one angled ion implantation to enlarge the first cut feature and the second cut feature
Data Source
AI summary
A method for forming a semiconductor structure includes forming a pattern having first and second line features extending in a first direction on a substrate. After depositing a photoresist layer on the substrate to cover the pattern, the photoresist layer is patterned to form a cut pattern including first and second cut features exposing portions of the respective first and second line features. In a top view, at least one of the first and second cut features is asymmetrically arranged with respect to a central axis of a corresponding first or second line feature. At least one angled ion implantation is performed to enlarge the first and second cut features in at least one direction perpendicular to the first direction. The portions of the first and second line features exposed by the respective first and second cut features are then removed.