Dummy Fin Recessing via Segmented Grouping for FinFET Uniformity
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Solution Overview
Problem
The complexity of manufacturing semiconductor devices, particularly FinFETs, increases with the scaling down of IC geometry, leading to challenges in uniformity and reproducibility due to the need for precise etching and patterning of dummy semiconductor fins, which can damage active features and complicate the process.
Innovation Solution
A method involving the formation of dummy semiconductor fins grouped into multiple fin groups, where each group is recessed separately using a tri-layer photoresist process with specific etching techniques to achieve uniform recess heights and surface profiles, preventing damage to active features and allowing for the formation of an isolation structure that embeds the recessed dummy fins, thereby facilitating the manufacturing of FinFETs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If dummy semiconductor fins are formed and recessed in the conventional manner, then the isolation structure can be formed, but the active features may be damaged and the manufacturing precision deteriorates
Solution Approach 1:
The dummy fins are segmented into different groups (first group, second group, third group) with different recess depths. The first group is recessed to a first depth, the second group to a second depth, and the third group to a third depth. This segmentation allows each group to be processed independently with optimized etching parameters, preventing damage to active features while maintaining manufacturing precision.
Solution Approach 2:
Different regions of the dummy fins are given different local qualities through selective recessing. The first group of dummy fins has a first recess depth, the second group has a second recess depth, and the third group has a third recess depth. This local differentiation allows the isolation structure to be formed without uniformly affecting all dummy fins, thereby protecting active features located in specific regions.
2Productivity
If the geometry size is scaled down to increase functional density, then production efficiency improves, but the etching and patterning process complexity increases
Solution Approach 1:
The etching process is segmented into multiple selective etching steps, each targeting a specific group of dummy fins. The first selective etching process recesses the first group, the second selective etching process recesses the second group, and the third selective etching process recesses the third group. This segmentation simplifies each individual etching step while achieving the complex overall structure required for scaled-down geometries.
Solution Approach 2:
The dummy fins are pre-grouped into first, second, and third groups before the etching process begins. This preliminary classification allows the subsequent etching processes to be performed more efficiently with optimized parameters for each group, reducing the overall process complexity despite the scaled-down geometry requirements.
3Loss of time
If multiple dummy fins are recessed simultaneously, then the process time is reduced, but the height uniformity and surface profile control deteriorate
Solution Approach 1:
The recessing process is divided into three separate selective etching processes, each targeting a specific group of dummy fins. Although this segmentation increases the number of process steps, each step can be optimized for uniformity and precision. The first selective etching process achieves uniform recessing of the first group, the second process uniformly recesses the second group, and the third process uniformly recesses the third group, thereby maintaining height uniformity while managing process time.
Data Source
AI summary
A method for manufacturing a semiconductor structure includes forming a plurality of dummy semiconductor fins on a substrate. The dummy semiconductor fins are adjacent to each other and are grouped into a plurality of fin groups. The dummy semiconductor fins of the fin groups are recessed one group at a time.