Mandrel-Spacer Patterning for Dense IC Layout Blocks
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Solution Overview
Problem
In integrated circuit (IC) manufacturing, the use of conventional optical lithography technologies at smaller technology nodes leads to inaccuracies such as rounding, pinching, and bridging of device features, which are exacerbated by the need for restrictive design rules and large spaces between layout blocks, resulting in reduced design density and increased 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 a mandrel-spacer double patterning process to improve pattern density and shape accuracy, thereby reducing the width of the cut pattern and enhancing the critical dimension of fins during etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional optical lithography is used at smaller technology nodes, then manufacturing process is simpler, but image printing quality deteriorates with rounding, pinching, and bridging of device features
Solution Approach 1:
The patent applies segmentation by dividing the patterning process into two separate steps: first forming mandrel patterns, then forming spacer patterns. This double patterning approach allows each step to work within the resolution capabilities of conventional optical lithography while achieving finer final feature dimensions and better shape accuracy that would be impossible with a single lithography step at smaller technology nodes.
Solution Approach 2:
The patent uses preliminary action by first forming the mandrel patterns that serve as templates before creating the final device features. These mandrels are formed with deliberate spacing and geometry that anticipates the subsequent spacer formation process, allowing the spacers to self-align and form accurate features without requiring the lithography system to directly resolve the final feature dimensions.
2Manufacturing precision
If restrictive design rules are applied to improve image printing quality, then device feature accuracy improves, but design density decreases due to larger required spacing between layout blocks
Solution Approach 1:
The patent transitions from two-dimensional planar patterning to three-dimensional spacer structures. By forming spacers that extend vertically from the mandrel patterns, the process achieves fine feature dimensions in the horizontal plane through vertical dimension utilization. This allows tighter spacing between layout blocks while maintaining feature accuracy, effectively increasing design density without sacrificing image printing quality.
Solution Approach 2:
The patent introduces mandrel patterns as intermediary structures that mediate between the lithography process and the final device features. These mandrels serve as temporary templates that enable tighter spacing between functional layout blocks while ensuring accurate feature formation through the subsequent spacer process, thereby increasing design density without compromising manufacturing precision.
3Reliability
If large spaces are provided between layout blocks to accommodate printing inaccuracy, then manufacturing reliability improves, but area utilization decreases
Solution Approach 1:
The patent changes the critical parameters of the patterning process by using double patterning with mandrels and spacers. This transforms the spacing requirements from being based on direct lithographic resolution limits to being based on spacer thickness control, which can be more precisely managed. The process enables reduced spacing between layout blocks while maintaining manufacturing reliability through better parameter control in the spacer formation step.
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, increases pattern density, improves fin uniformity, and decreases manufacturing costs by eliminating the need for large spacing areas, while maintaining compliance with manufacturing rules and enhancing the shape and critical dimension of etched features.
Implementation Method 1
mandrel-spacer double patterning process to improve pattern density and shape accuracy
Data Source
AI summary
A method includes forming a first mandrel pattern and a second mandrel pattern. The first mandrel pattern includes at least first and second mandrels for a mandrel-spacer double patterning process. The second mandrel pattern includes at least a third mandrel inserted between the first and second mandrels. The first mandrel pattern and the second mandrel pattern include a same material. The first and second mandrels are merged together with the third mandrel to form a single pattern.