Self-aligned Block Patterning Density Assist Patterns
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Solution Overview
Problem
The self-aligned block patterning process in semiconductor manufacturing faces challenges with low pattern density, leading to uniformity issues and increased defect rates in EUV masks, particularly due to the low density of block mask layouts, which affects the fabrication of metal lines and increases E-beam writing time.
Innovation Solution
A method is introduced to generate mask layouts with density assist patterns for self-aligned block patterning, including the creation of mandrel and non-mandrel block mask layouts with specific density assist patterns, achieving a pattern density of 30% or greater, which improves uniformity and reduces defects by enhancing the alignment and etch selectivity between different patterning stack materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If block mask layout uses low density patterns to isolate portions not to be etched, then the mask can define metal lines, but mask uniformity deteriorates and defect rates increase
Solution Approach 1:
The mask layout is segmented into functional block patterns (for metal line isolation) and density assist patterns (to improve uniformity). The density assist patterns are distributed throughout the mask to provide a minimum pattern density of 30%, while block patterns maintain their isolation function. This segmentation allows the mask to simultaneously achieve metal line definition and improved uniformity.
Solution Approach 2:
Density assist patterns serve as intermediary elements that mediate between the low-density block patterns and the requirements for mask uniformity. These assist patterns do not interfere with the metal line cutting function but provide the necessary pattern density to improve mask fabrication uniformity and reduce defects.
2Ease of manufacture
If block mask layout uses low density patterns, then metal line isolation is achieved, but E-beam writing time increases
Solution Approach 1:
The mask layout is segmented into functional block patterns and density assist patterns. By adding density assist patterns, the overall pattern density increases to at least 30%, which reduces E-beam writing time while the block patterns maintain their metal line isolation function.
Solution Approach 2:
The pattern density parameter is changed from low density to at least 30% density by introducing density assist patterns. This parameter change reduces E-beam writing time while maintaining the metal line isolation capability through the block patterns.
3Ease of manufacture
If block mask layout uses low density patterns, then metal line isolation is achieved, but pattern uniformity deteriorates
Solution Approach 1:
The mask layout is segmented into block patterns for isolation and density assist patterns for uniformity. The density assist patterns are distributed to achieve minimum 30% pattern density, improving mask uniformity while block patterns maintain isolation function.
Solution Approach 2:
The pattern density parameter is increased to at least 30% by introducing density assist patterns, which improves mask uniformity and reduces pattern variation while maintaining the metal line isolation capability.
Data Source
AI summary
A method of generating mask layouts for self-aligned block patterning is provided. Metal line patterns to be formed on a semiconductor substrate is identified. A mandrel mask layout for first mask based on the metal line patterns is generated in view of a self-aligned double patterning (SADP) process for forming a plurality of mandrels on the semiconductor substrate. The mandrel mask layout may include a plurality of mandrel patterns. A non-mandrel block mask layout for second mask is generated based on the mandrel mask layout for cutting metal lines formed under gaps between spacers in non-mandrel area on the semiconductor substrate. The non-mandrel block mask layout may include a plurality of first block patterns and a plurality of first density assist patterns. A mandrel block mask layout for third mask is generated based on the mandrel mask layout for cutting metal lines formed under mandrel area on the semiconductor substrate.