Semiconductor Fin Etching for Uniform Channel Lengths
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Solution Overview
Problem
As semiconductor devices continue to integrate more components into a given area through reduced minimum feature sizes, challenges arise in forming precise and uniform features, particularly in finFET devices, leading to issues like depth loading and non-uniform channel lengths, which affect device performance and uniformity.
Innovation Solution
A method involving anisotropic and isotropic etching processes is employed to form precise openings in semiconductor fins, using a selective modulation device to filter charged plasma ions and utilize radical etching to reshape openings, resulting in controlled channel lengths and reduced depth loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If minimum feature sizes are reduced to increase integration density, then more components can be integrated into a given area, but manufacturing precision deteriorates due to depth loading and non-uniform channel lengths
Solution Approach 1:
The etching process is divided into multiple sequential steps: anisotropic etching to form initial openings, followed by isotropic etching to reshape and round the openings. This segmentation allows each etching step to be optimized independently, with the anisotropic step providing directional control and the isotropic step providing uniform rounding, thereby maintaining precision at reduced feature sizes
Solution Approach 2:
The patent employs periodic alternating etching actions with different directional characteristics. The process alternates between anisotropic etching (vertical direction predominates) and isotropic etching (all directions equally), creating a periodic pattern of material removal that progressively shapes the openings while compensating for depth loading effects
2Ease of manufacture
If conventional etching processes are used to form openings in fins, then the process is simple, but depth loading causes non-uniform channel lengths and rounding variations
Solution Approach 1:
The patent changes the etching parameters by alternating between two distinct etching modes with different kinetic characteristics. The anisotropic etching uses parameters optimized for vertical directionality, while the isotropic etching uses parameters optimized for uniform material removal in all directions. This parameter switching compensates for depth loading by adjusting the etching behavior at different stages of opening formation
Solution Approach 2:
Different etching qualities are applied to different stages of the opening formation process. The anisotropic etching provides localized vertical precision for defining the opening position and initial depth, while the isotropic etching provides localized uniform rounding at the opening edges. Each local region of the fin structure receives the appropriate etching quality needed for that specific formation stage
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 enhances the precision of feature formation, improving device performance by minimizing rounding and depth loading variations, thereby increasing wafer acceptance and performance consistency across different regions.
Implementation Method 1
a plasma is formed from a precursor and radicals are extracted from the plasma while charged particles are filtered from the plasma
Implementation Method 2
radicals are extracted from the plasma while charged particles are filtered from the plasma using a selective modulation device
Implementation Method 3
A first opening is formed in a fin with a first anisotropic etching process
Implementation Method 4
the first opening is reshaped into a second opening with a second radical etching process
Data Source
AI summary
A manufacturing process and device are provided in which a first opening in formed within a substrate. The first opening is reshaped into a second opening using a second etching process. The second etching process is performed with a radical etch in which neutral ions are utilized. As such, substrate push is reduced.