Cut Pattern Modification for IC Manufacturability
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Solution Overview
Problem
Current mandrel-cut double patterning techniques for semiconductor integrated circuits (ICs) face challenges due to complicated pattern layouts and narrow end-to-end spaces between patterns, making mask and wafer fabrication difficult, particularly for FinFETs, which can lead to issues like pattern shorting and increased manufacturing complexity.
Innovation Solution
The method involves modifying cut patterns by splitting them into subsets for separate masks, replacing elongated patterns with smaller or square patterns, and adjusting cut layers to avoid overlapping with via features, thereby increasing spacing and reducing pattern length, which enhances manufacturability and the photolithography process window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mandrel-cut double patterning technique is used to fabricate high density IC devices, then photolithographic process window is improved, but pattern layout becomes complicated and end-to-end spaces between patterns become narrow
Solution Approach 1:
The cut pattern is divided into multiple subsets (first subset and second subset) that are formed by separate masks. This segmentation allows each subset to have simpler, more manufacturable patterns while collectively achieving the desired cut functionality, thereby resolving the contradiction between manufacturing precision and layout complexity
Solution Approach 2:
The patent introduces a new dimension by using multiple mask layers (first mask and second mask) to form different subsets of the cut pattern. Instead of attempting to form all cut patterns in a single layer, the solution distributes patterns across multiple layers, simplifying each individual layer's pattern complexity while maintaining overall manufacturing precision
2Productivity
If cut pattern design is optimized for density, then manufacturing efficiency is improved, but end-to-end spaces between patterns become narrow causing fabrication difficulties
Solution Approach 1:
By segmenting the cut pattern into multiple subsets formed by different masks, the patent allows each subset to have adequate spacing for easy fabrication. The segmentation maintains manufacturing efficiency through optimized pattern distribution while ensuring each individual pattern subset meets minimum spacing requirements for ease of manufacture
Solution Approach 2:
The patent applies different pattern densities and spacing characteristics to different regions and subsets of the cut pattern. Each mask layer can be optimized with appropriate local spacing and pattern density, allowing high overall manufacturing efficiency while maintaining adequate local spaces for easy mask and wafer fabrication
3Productivity
If pattern density is increased for higher IC density, then production efficiency is improved, but pattern shorting risk increases
Solution Approach 1:
The cut pattern is segmented into multiple subsets formed by separate masks, which allows better control over spacing and reduces the risk of pattern shorting. This segmentation enables higher overall pattern density while maintaining adequate clearance between individual patterns through the multi-layer approach
Solution Approach 2:
By distributing cut patterns across multiple mask layers (adding a vertical dimension), the patent achieves higher effective pattern density on the wafer while maintaining adequate horizontal spacing between patterns on each individual layer, thereby preventing pattern shorting while improving production efficiency
Data Source
AI summary
A method of manufacturing an integrated circuit (IC) includes receiving a layout of the IC having a first region interposed between two second regions. The layout includes a first layer having first features and second and third layer having second and third features in the first region. The second and third features collectively form cut patterns for the first features. The method further includes modifying the second and third features by a mask house tool, resulting in modified second and third features, which collectively form modified cut patterns for the first features. The modifying of the second and third features meets at least one of following conditions: total spacing between adjacent modified second (third) features is greater than total spacing between adjacent second (third) features, and total length of the modified second (third) features is smaller than total length of the second (third) features.