Metal Gate Cut Etching for Uniform Depth Across Widths
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Solution Overview
Problem
The challenge in integrated circuit fabrication lies in forming gate cuts with varying widths but similar heights, as current methods result in inconsistent depths due to loading effects during etching, which can disrupt backside structures and interfere with processing.
Innovation Solution
Employing distinct plasma-based etching processes for gate cuts of different widths, adjusting the etch duration to ensure similar heights for both narrow and wide cuts, thereby maintaining consistent depth and reducing interference with backside processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single etching process is used for all gate cuts, then the process is simple, but gate cuts of different widths will have different heights due to loading effects
Solution Approach 1:
The patent divides the gate cut formation process into multiple separate etching processes based on gate cut width categories. Narrow gate cuts (e.g., <50nm) are etched using a first etching process, while wider gate cuts (e.g., ≥50nm) are etched using a second etching process. This segmentation eliminates loading effects between different width categories and ensures consistent heights across all gate cuts despite their width variations.
2Adaptability or versatility
If gate cuts are etched to different depths to accommodate varying widths, then width variation is achieved, but backside structures are disrupted and processing is interfered with
Solution Approach 1:
The patent applies different etching conditions (etch time, power, gas flow rates) tailored to specific gate cut width ranges. Narrow gate cuts receive a first set of etching parameters, while wider gate cuts receive a second set of parameters. This localized optimization ensures each gate cut achieves the target depth without over-etching, thereby preventing disruption to backside structures while still accommodating the required width variations.
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 allows for the formation of gate cuts with different widths having heights that vary by no more than 10-20%, ensuring consistent integration and minimizing disruptions to backside structures, thus enhancing the fabrication process.
Implementation Method 1
Employing distinct plasma-based etching processes to form gate cuts of different widths
Data Source
AI summary
Techniques are provided herein to form semiconductor devices that include gate cuts with different widths (e.g., at least a 1.5× difference in width) but substantially the same height (e.g., less than 5 nm difference in height). A given gate structure extending over one or more semiconductor regions may be interrupted with any number of gate cuts that each extend through an entire thickness of the gate structure. According to some embodiments, gate cuts of a similar first width are formed via a first etching process while gate cuts of a similar second width that is greater than the first width are formed via a second etching process that is different from the first etching process. Using different etch processes for gate cuts of different widths maintains a similar height for the gate cuts of different widths.