Metal Gate Cut Etching for Uniform Depth Across Widths
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As integrated circuits shrink in size, forming gate cuts with different widths but similar heights becomes challenging due to limitations in current fabrication technologies, leading to issues with device isolation and backside structure disruption.
Innovation Solution
The use of distinct plasma-based etching processes to form gate cuts of varying widths, with wider cuts having shorter etch durations to maintain similar depths, allowing for gate cuts with height-to-width aspect ratios of 5:1 or higher and ensuring consistent height within 10% of each other.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single etching process is used to form gate cuts of different widths, then the process is simple, but the height control becomes poor due to loading effects
Solution Approach 1:
The patent divides the gate cut formation into multiple separate etching processes: a first etching process forms initial gate cuts, and a second etching process forms additional gate cuts. This segmentation allows each etching process to be optimized independently for its specific width requirements, thereby achieving consistent height control across gate cuts of different widths while maintaining process simplicity through modular fabrication steps.
2Length of stationary object
If longer etching duration is used to achieve sufficient depth, then the gate cuts reach required depth, but backside structures are disrupted
Solution Approach 1:
The patent performs preliminary actions by forming masking structures and sacrificial structures before the etching processes. These preliminary structures define precise etch boundaries and protect backside structures from damage. The masking structures are formed with specific patterns that guide the etching depth, ensuring that gate cuts reach the required depth without extending too deep and disrupting backside structures.
3Area of stationary object
If wider gate cuts are formed, then isolation is improved, but the etching depth becomes excessive relative to the width
Solution Approach 1:
The patent applies local quality by using different etching parameters and masking structures for different gate cut locations. Wider gate cuts are formed with etching conditions optimized for their specific width, while narrower gate cuts use different conditions. This localized optimization ensures that each gate cut achieves the appropriate height-to-width ratio for its specific width, preventing excessive depth relative to width while maintaining effective isolation.
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 enables the formation of gate cuts with different widths while maintaining similar heights, improving device isolation and preventing backside structure disruption, thus enhancing the fabrication of densely packed transistors.
Implementation Method 1
Employing different plasma-based etching processes to form gate cuts of different widths
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 2C~2D
AI summary
Techniques are provided herein to form semiconductor devices that include gate cuts with different widths (e.g., at least a 1.5x 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.