Fin Sidewall Protection During Semiconductor Trench Etching
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Solution Overview
Problem
Conventional semiconductor devices, such as fin field-effect transistors, face challenges with poor control over channel current and severe current leakage due to issues in the formation process, including inconsistent etching and damage to fin sidewalls during the removal of second-type fins and substrate etching.
Innovation Solution
A method is developed to form semiconductor devices by creating first-type and second-type fin groups on a substrate, where second-type fins are removed to form trenches, and a protective layer is applied to the sidewalls of the first-type fins to prevent damage during substrate etching, allowing for the formation of second trenches using the protective layer as an etch mask.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If second-type fins are removed by etching to form trenches, then device isolation is improved, but fin sidewalls suffer etching damage
Solution Approach 1:
A protective layer is introduced as an intermediary between the etching process and the fin sidewalls. This protective layer is formed on the sidewalls of first-type fins before the second-type fins are removed, serving as a mediator that prevents direct contact between the etching solution and the fin sidewalls, thereby eliminating etching damage while maintaining effective device isolation.
Solution Approach 2:
The protective layer is formed in advance before the etching of second-type fins begins. This preliminary action ensures that the fin sidewalls are already protected when the etching process starts, preventing any potential etching damage from occurring during the trench formation process.
2Reliability
If substrate etching is performed to form second trenches, then isolation performance is enhanced, but fin structure integrity deteriorates
Solution Approach 1:
The protective layer serves as a mediator during substrate etching, allowing the etching process to proceed into the substrate to form second trenches for enhanced isolation, while simultaneously protecting the fin structure from direct etching exposure, thus maintaining fin structure integrity throughout the process.
Solution Approach 2:
The protective layer is selectively removed after the etching process is complete, extracting only the protective material while leaving the fin structure intact. This allows the benefits of enhanced isolation from the second trenches to be realized without the protective layer interfering with subsequent processing steps.
3Ease of manufacture
If conventional etching is used without protective measures, then manufacturing complexity is reduced, but manufacturing precision deteriorates
Solution Approach 1:
The protective layer acts as a self-aligned etch mask that automatically defines the precise location and dimensions of the trenches. By forming the protective layer directly on the fin sidewalls, the etching process self-aligns to create trenches with high precision without requiring additional alignment steps or complex masking procedures, thus maintaining ease of manufacture while achieving high manufacturing precision.
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 method improves the performance of semiconductor devices by reducing etching damage, maintaining the integrity of fin sidewalls, and ensuring consistent isolation performance through self-aligned second trenches, thereby enhancing the overall performance and reliability of the semiconductor device.
Implementation Method 1
a protective layer is applied to the sidewalls of the first-type fins to prevent damage during substrate etching, allowing for the formation of second trenches using the protective layer as an etch mask
Data Source
AI summary
Semiconductor device and fabrication method are provided. A plurality of first-type fin groups and second-type fins, each between the first-type fin groups, are formed on a substrate. A first-type fin group includes first-type fins. The first-type fins and the second-type fins are arranged in a direction perpendicular to an extending direction of the first-type fins and the second-type fins. The second-type fins are removed to form first trenches between corresponding first-type fin groups. A protective layer is formed on sidewalls of the first trenches after removing the second-type fins. The protective layer covers sidewalls of the first-type fins that are perpendicular to a width direction of the first-type fins. Second trenches are formed in the substrate under the first trenches by etching the substrate at bottoms of the first trenches using the protective layer as an etch mask.