Self-Aligned Double Patterning Line Cut Alignment
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Solution Overview
Problem
In photolithography processes for integrated circuit manufacturing, achieving precise alignment for the removal of spacer layer ends is challenging due to low distinguishability between the spacer layer and photoresist, which affects the accuracy of line cut processes in self-aligned double patterning techniques.
Innovation Solution
The method involves using a line termini mark made of both mandrel and spacer materials for alignment during the lithography process, enhancing the visibility and accuracy of the line cut photolithography by utilizing the mandrel material for the mark, thereby providing a robust photo alignment signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a spacer layer is formed on mandrels for self-aligned double patterning, then feature pitch is reduced below the critical dimension limit, but the spacer layer becomes indistinguishable from the photoresist during lithography, reducing alignment precision
Solution Approach 1:
The patent applies local quality by creating a line termini mark with a specific material composition (containing mandrel material) that is locally placed at the ends of spacers. This local modification provides enhanced optical contrast and distinguishability at critical locations without altering the overall spacer structure or material, thereby maintaining the pitch-split capability while improving alignment precision for line cut processes.
2Manufacturing precision
If photolithography is used to remove spacer layer ends, then line cut precision is required, but low distinguishability between spacer and photoresist degrades alignment accuracy
Solution Approach 1:
The patent utilizes color changes (optical contrast differences) by incorporating mandrel material into the line termini mark. This creates a distinct optical signature that enhances the visibility and detectability of the mark during photolithography alignment, allowing for more accurate detection and measurement of the line termini positions despite the general indistinguishability of spacer and photoresist materials.
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 improves the precision of the line cut process, allowing for more accurate positioning and removal of spacer layer ends, leading to improved feature resolution and manufacturing efficiency in integrated circuit device production.
Implementation Method 1
In conventional photolithography, a photoresist is exposed to light through a lithographic mask. The photoresist is modified by the exposure in such a way that either the exposed or unexposed portions of the resist can be removed during subsequent development.
Data Source
AI summary
The present disclosure relates to integrated circuit device manufacturing processes. A self-aligned double patterning method is provided. In the method, a lithography process for line cut that determines the locations of line termini is performed after forming a spacer layer alongside the mandrel and prior to stripping the mandrel. The lithographic mask for the line cut is aligned to the mandrel and the spacer layer using a mark made of the mandrel material and the spacer material. Compared to the previous approach where the line cut process is performed after the mandrel removal, in the disclosed approach, the line termini mask is made of the mandrel material and the spacer material, and is more distinguishable compared to a mark made of just the spacer material. Thereby, the methods provide robust photo alignment signal for the line cut photolithography and precise positioning of the line termini mask.