Serpentine Cut Mask Layout for FinFET Contact Patterning
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Solution Overview
Problem
As semiconductor devices continue to shrink in feature size, the integration density of electronic components increases, but this leads to challenges such as reduced conductivity and contact resistance due to rounding during photolithographic steps, and increased risk of bridging or process defects in forming source/drain contacts in FinFET devices.
Innovation Solution
The use of a serpentine cut mask with straight sections that are substantially perpendicular to each other, reducing rounding and allowing for larger source/drain contacts and closer spacing without increased risk of bridging, by forming cut regions with a serpentine pattern that includes bridge sections approximately perpendicular to cut sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithographic patterning is used to form cut regions, then manufacturing process simplicity is maintained, but rounding occurs at corners leading to reduced conductivity and increased contact resistance
Solution Approach 1:
The cut pattern is divided into multiple straight cut sections connected by bridge sections, where each cut section is separated by a bridge section. This segmentation allows each segment to be formed with straight edges using conventional photolithography, avoiding corner rounding while maintaining manufacturing simplicity.
Solution Approach 2:
The serpentine pattern extends the cut regions in a two-dimensional layout with alternating directions, allowing straight cut sections to be arranged in a serpentine configuration. This dimensional arrangement enables sharp corners to be maintained by using bridge sections that connect perpendicular cut sections without requiring curved transitions.
2Productivity
If cut regions are spaced closer together to increase integration density, then device miniaturization is achieved, but the risk of bridging and process defects increases
Solution Approach 1:
The serpentine cut pattern segments the continuous cut regions into discrete sections separated by bridge sections. This segmentation creates natural spacing and isolation between cut regions, reducing the risk of bridging even when overall integration density is increased through closer placement of serpentine units.
Solution Approach 2:
The bridge sections act as intermediary elements between adjacent cut sections. These bridge sections provide a buffer zone that prevents direct contact or bridging between cut regions, enabling closer spacing of cut regions while maintaining process reliability and reducing defect formation.
3Productivity
If feature sizes are reduced to increase integration density, then more components can be integrated, but conductivity and contact resistance are degraded due to rounding
Solution Approach 1:
By segmenting the cut pattern into straight sections connected by bridges, the invention maintains precise geometric control at each segment endpoint. This segmentation approach preserves contact geometry precision even as overall feature sizes are reduced, because each segment can be formed with sharp, well-defined edges using conventional lithography.
Solution Approach 2:
The invention deliberately avoids curved transitions in the cut pattern by using straight bridge sections instead of curved corners. This anti-curvature approach prevents rounding effects that would degrade contact geometry precision, allowing sharp, precise contact interfaces to be maintained at reduced feature sizes.
Data Source
AI summary
A method includes forming fins extending over a semiconductor substrate; forming a photoresist structure over the fins; patterning a serpentine cut pattern in the photoresist structure to form a cut mask, wherein the serpentine cut pattern extends over the fins, wherein the serpentine cut pattern includes alternating bridge regions and cut regions, wherein each cut region extends in a first direction, wherein each bridge region extends between adjacent cut regions in a second direction, wherein the second direction is within 30° of being orthogonal to the first direction; and performing an etching process using the cut mask as an etching mask.