Mandrel And Spacer Patterning for Mixed-Density Active Patterns
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Solution Overview
Problem
Conventional optical lithography technologies struggle to accurately print intricate device features in integrated circuits due to resolution limits, leading to issues like rounding, pinching, necking, bridging, dishing, and thickness variations, especially in ICs with mixed layout blocks requiring different design rules, which increases space and manufacturing costs.
Innovation Solution
The method involves inserting dummy mandrel patterns between layout blocks to connect line patterns, reducing the space required between them, and using spacer patterning techniques to improve pattern density and uniformity, thereby adhering to manufacturing rules without increasing the overall area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optical lithography is used for patterning, then manufacturing process is simple, but image printing quality deteriorates due to resolution limits causing rounding, pinching, necking, bridging, dishing, and erosion
Solution Approach 1:
The patterning process is divided into multiple steps: forming mandrels at a first pitch, depositing spacers, selectively removing portions, and forming final patterns at a second pitch. This segmentation allows each step to be optimized independently, achieving high precision patterns that would be impossible in a single lithography step.
Solution Approach 2:
Mandrels are formed in advance as templates before the final pattern is created. These preliminary mandrel structures guide the subsequent spacer deposition and pattern formation, enabling precise control over final pattern dimensions and shapes.
2Manufacturing precision
If restrictive design rules are applied to improve image printing quality, then pattern uniformity improves, but space between layout blocks increases
Solution Approach 1:
The method enables different pitch parameters to be used in different regions: smaller pitches can be used within layout blocks for high-density patterns, while the spacer-based patterning allows controlled spacing between blocks. This parameter flexibility reduces the need for excessive spacing while maintaining pattern quality.
3Area of stationary object
If smaller pitches are used for area reduction, then device integration increases, but image printing accuracy deteriorates due to resolution limits
Solution Approach 1:
The invention transitions from two-dimensional lithographic patterning to three-dimensional spacer-based patterning. By depositing conformal spacers on mandrels and then anisotropically etching, patterns at smaller pitches are achieved through vertical spacer thickness control rather than lateral lithographic resolution, effectively adding a dimensional degree of freedom to the patterning process.
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 reduces the space between layout blocks, enhances pattern density, improves fin uniformity and critical dimensions, and decreases manufacturing costs by minimizing unnecessary spacing, while maintaining compliance with design rules.
Implementation Method 1
a spacer is formed on sidewalls of the mandrel pattern
Implementation Method 2
a spacer is formed on sidewalls of the mandrel pattern
Implementation Method 3
The mandrel pattern is then anisotropically etched using the spacer as a mask
Implementation Method 4
The spacer pattern is then used to form a fin pattern in the substrate
Data Source
AI summary
A method of fabricating a semiconductor device includes generating at least one photomask based on a layout and forming a plurality of active patterns on a substrate, using the at least one photomask. The layout includes a plurality of first patterns that extend parallel to each other in a first direction on a low-density region of the layout and a plurality of second patterns that extend parallel to each other in the first direction on a high-density region of the layout. The forming of the plurality of active patterns includes using the first patterns and the second patterns of the layout to respectively form a plurality of first active patterns and a plurality of second active patterns on the substrate.