Fanout Pattern Layout for Self-Aligned Double Patterning
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Solution Overview
Problem
The challenge in integrated circuit manufacturing is to minimize optical proximity effects in fanout areas to ensure reliable production of word lines, as existing multiple patterning methods can lead to reliability issues such as weakened or shorted word lines due to nonuniform pitches and critical dimension biases.
Innovation Solution
A circuit structure and manufacturing method involving self-aligned double patterning, where first conducting lines and linking lines are formed with specific pitches and connection structures, including segments with varying pitches, to mitigate optical proximity effects, allowing for reliable connection and current flow between word lines and landing pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple patterning methods are used to reduce pitch, then circuit density is improved, but optical proximity effects cause reliability issues with word lines
Solution Approach 1:
The patent applies different pitch values to different regions of the fanout pattern. Specifically, connection structures have a first pitch while linking lines have a second pitch that is greater than the first pitch. This local variation in pitch prevents optical proximity effects from causing uniform line width variations, thereby maintaining word line reliability while still achieving density improvements through multiple patterning.
Solution Approach 2:
The patent changes the pitch parameter across different regions of the circuit pattern. By varying the pitch between connection structures and linking lines, the optical proximity effects are modulated to prevent critical dimension biases that would otherwise weaken or short word lines. This parameter change approach allows the use of multiple patterning while maintaining manufacturing precision.
2Adaptability or versatility
If fanout pattern with nonuniform pitches is used to connect array to pads, then adaptability is improved, but optical proximity effects increase causing critical dimension bias
Solution Approach 1:
The patent implements local quality by assigning different pitch values to specific regions: connection structures use a first pitch optimized for connecting to array lines, while linking lines use a second pitch (greater than the first) optimized for connecting to pads. This localized pitch optimization maintains adaptability while controlling critical dimensions by preventing excessive optical proximity effects in any single region.
Data Source
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AI summary
A circuit structure comprises a plurality of first conducting lines extending in a first direction, the first conducting lines having a first pitch in a second direction orthogonal to the first direction; a plurality of linking lines extending in the second direction, the linking lines having a second pitch in the first direction, the second pitch being greater than the first pitch; and a plurality of connection structures connecting respective first conducting lines for current flow to respective linking lines, the connection structures each including a plurality of segments extending in the first direction, segments in the plurality of segments having a transition pitch in the second direction relative to adjacent segments in the plurality of segments greater than or equal to the first pitch, and less than the second pitch.