Fin-FET Doping via Isolation Layer Diffusion
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Solution Overview
Problem
Fin-FET devices face challenges in electrical performance and stability due to ion-implantation shadow effects and lattice damages caused by high-energy doping ions directly implanted into fin structures, which cannot be recovered in subsequent fabrication processes.
Innovation Solution
A method is developed to fabricate Fin-FET devices by forming fin structures with an initial isolation layer, where doping ions are implanted into the isolation layer perpendicular to the substrate, allowing them to diffuse laterally into the fin structures, thereby avoiding shadow effects and reducing lattice damage. This method includes forming a base structure, creating a linear oxide layer, forming an isolation film, and removing portions to create an initial isolation layer with a lower top surface, allowing precise ion implantation and subsequent annealing to activate the ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-energy doping ions are directly implanted into fin structures, then doping efficiency is improved, but lattice damage occurs and cannot be recovered
Solution Approach 1:
The patent applies preliminary action by forming a sacrificial oxide layer on the fin structures before ion implantation. This oxide layer serves as a protective buffer that absorbs the impact of high-energy doping ions, preventing direct damage to the crystal lattice while still allowing the doping process to proceed effectively. The oxide layer is subsequently removed to reveal the doped fin structures with minimal lattice damage.
2Productivity
If doping ions are implanted directly into fin structures, then doping speed is improved, but shadow effects reduce doping uniformity
Solution Approach 1:
The patent employs an intermediary approach by introducing a sacrificial oxide layer as a mediator between the doping ions and the fin structures. This oxide layer fills in the shadowed regions and provides a uniform surface for ion implantation, ensuring that doping ions are distributed evenly across all fin structures including those in shadowed areas. The intermediary layer is then removed after doping, leaving uniform doping profiles without shadow effects.
3Device complexity
If conventional ion implantation is used, then process simplicity is maintained, but electrical performance and stability deteriorate
Solution Approach 1:
The patent applies segmentation by dividing the conventional single-step ion implantation process into multiple distinct steps: (1) forming a sacrificial oxide layer on the fin structures, (2) performing ion implantation through the oxide layer, (3) removing the oxide layer, and (4) performing annealing. This segmentation allows each step to be optimized independently, resulting in improved electrical performance and stability while maintaining overall process manageability.
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 improves the electrical performance and stability of Fin-FET devices by preventing ion implantation damages and ensuring effective doping, resulting in enhanced transistor quality and performance.
Implementation Method 1
implanting doping ions into the initial isolation layer
Implementation Method 2
allowing them to diffuse laterally into the fin structures
Implementation Method 3
subsequent annealing to activate the ions
Data Source
AI summary
A Fin-FET device and its fabrication method are provided. The method for fabricating the Fin-FET device includes forming a plurality of fin structures on a substrate, forming an isolation film on the substrate between neighboring fin structures, removing a portion of the isolation film to form an initial isolation layer with a top surface of the initial isolation layer lower than top surfaces of the fin structures, and implanting doping ions into the initial isolation layer. Further, the method also includes removing a portion of the initial isolation layer to form an isolation layer.