Photomask Layout for Fine Patterns via Double Patterning
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Solution Overview
Problem
As semiconductor devices become more highly integrated, there is a need for improved photomask layouts and methods to form fine patterns with higher resolution and reliability, particularly in the double patterning process, where achieving precise and consistent hole formation is challenging due to the complexity of sacrificial structures and spacers.
Innovation Solution
The method involves forming first and second sacrificial patterns with specific geometries, including tab portions wider than line portions, and corresponding spacers to create intersecting patterns that allow for precise etching of target layers, enabling the formation of high-resolution contact holes by alternating gap widths between spacers, thereby enhancing the resolution and reliability of pattern formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photomask layouts and single patterning processes are used, then the manufacturing process is simple, but the resolution and precision of formed patterns deteriorate as semiconductor devices become highly integrated
Solution Approach 1:
The patent applies segmentation by dividing the patterning process into multiple stages (first and second double patterning processes) and dividing the sacrificial patterns into distinct geometric components (line portions and tab portions). This multi-stage approach enables formation of finer contact holes with dimensions below what single patterning can achieve, directly resolving the contradiction between achieving high resolution and maintaining process simplicity.
Solution Approach 2:
The patent introduces dimensional variation through the tab portions of sacrificial patterns, which extend in directions different from the line portions. This dimensional approach allows the second spacers to be positioned at specific locations relative to first spacers, enabling precise control of contact hole positions and dimensions that cannot be achieved with conventional single-dimension patterning.
2Manufacturing precision
If double patterning process with sacrificial structures and spacers is used, then higher resolution patterns can be formed, but the process complexity and difficulty of achieving consistent hole formation increase
Solution Approach 1:
The patent applies local quality by designing sacrificial patterns with different geometric properties in different locations: line portions for general area coverage and tab portions for specific contact hole positioning. The tab portions have different dimensions and orientations than line portions, allowing localized control of spacer formation and contact hole characteristics, thereby simplifying the overall manufacturing process while maintaining high precision.
Solution Approach 2:
The patent implements preliminary action by pre-forming sacrificial patterns with specifically designed geometries (line and tab portions) before spacer formation. This preliminary geometric design ensures that subsequent spacer deposition automatically creates the desired contact hole positions and dimensions, reducing the need for additional alignment steps and simplifying the manufacturing process.
3Productivity
If critical dimension of target pattern is reduced for high integration, then device integration increases, but exposure equipment requirements and etching process complexity increase
Solution Approach 1:
The patent segments the pattern formation into multiple discrete steps with distinct sacrificial pattern geometries, allowing each step to be optimized independently. This segmentation enables formation of smaller critical dimensions through cumulative effect of multiple patterning cycles, achieving high device integration without requiring single-step ultra-fine exposure equipment.
Solution Approach 2:
The patent uses sacrificial patterns with line and tab portions as intermediary structures that mediate between the photomask design and final contact hole formation. These intermediary structures enable precise positioning and dimensioning of contact holes through spacer formation, allowing high integration density without directly exposing the final pattern at ultra-fine dimensions in a single step.
Data Source
AI summary
A method of forming fine patterns including forming a plurality of first sacrificial patterns on a target layer, the target layer on a substrate, forming first spacers on respective sidewalls of the first sacrificial patterns, removing the first sacrificial patterns, forming a plurality of second sacrificial patterns, the second sacrificial patterns intersecting with the first spacers, each of the second sacrificial patterns including a line portion and a tab portion, and the tab portion having a width wider than the line portion, forming second spacers on respective sidewalls of the second sacrificial patterns, removing the second sacrificial patterns, and etching the target layer through hole regions, the hole regions defined by the first spacers and the second spacers, to expose the substrate may be provided.