Self-Aligned Multiple Patterning Grid Structure Overlay
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Solution Overview
Problem
Current multiple patterning techniques in semiconductor manufacturing face challenges in achieving accurate positioning and dimensioning of mask patterns relative to grid structures, leading to overlay and dimensional errors that affect the final performance of the manufactured devices.
Innovation Solution
The method involves forming a first grid structure and a second grid structure with periodic arrangements, where the second grid structure constrains the modification locations during the lithographic process, improving accuracy by using a regular grid pattern as a guide instead of an arbitrary mask pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a circuit-specific mask pattern is used to modify the grid structure at product-specific locations, then the functional device pattern can be defined, but positioning and dimensioning errors occur due to overlay and dimensional inaccuracies
Solution Approach 1:
A second grid structure is introduced as an intermediary reference layer between the first grid structure and the mask pattern. This second grid structure serves as a mediator that provides accurate positioning references, enabling the mask pattern to be aligned with higher precision relative to the first grid structure, thereby reducing overlay and dimensional errors in the final device pattern
Solution Approach 2:
The second grid structure is formed in advance before the mask pattern application step. This preliminary formation of the reference grid structure allows subsequent mask alignment and modification processes to benefit from pre-established accurate positioning references, improving the overall manufacturing precision of the functional device pattern
2Manufacturing precision
If multiple patterning steps are performed to produce device features smaller than lithographic resolution, then finer dimensions are achieved, but overlay and dimensional errors increase
Solution Approach 1:
The second grid structure acts as an intermediary reference system that decouples the positioning accuracy requirement from the feature size reduction. By providing a stable reference framework, it enables multiple patterning steps to achieve finer dimensions while maintaining accurate overlay control, as the second grid structure serves as a consistent reference across all patterning steps
Solution Approach 2:
The patterning process is segmented into distinct stages with the second grid structure serving as a reference framework. This segmentation allows the complex multiple patterning process to be broken down into manageable steps, each with controlled overlay requirements relative to the second grid structure, thereby reducing cumulative dimensional errors
Data Source
AI summary
A functional device pattern is formed in a self-aligned multiple patterning process (e.g. SADP, SAQP). A first grid structure is formed on the substrate, the first grid structure including a plurality of elements in a first periodic arrangement. The first grid structure may be formed, for example, by a self-aligned pitch multiplication process. The first grid structure is then modified at specific locations in accordance with a cut mask, thereby to define the functional device pattern. In an intermediate step, a second grid structure is formed overlying the first grid structure. The second grid structure includes a plurality of elements in a second periodic arrangement. The elements of the second grid structure work in addition to the cut mask to constrain the locations at which the first grid structure is modified. Overlay and CD requirements of the cut mask can be relaxed.