Fin Structure Doping via Selective Dopant Source Layer Removal
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Solution Overview
Problem
Current methods for fabricating multi-gate field-effect transistors face challenges in achieving uniform doping concentration, particularly in three-dimensional structures, leading to short-channel effects and inadequate control over carrier channels.
Innovation Solution
A method involving the formation of a semiconductor device with a fin structure, where a dopant source layer is conformally deposited on the side and bottom surfaces of a recess, and then selectively removed from the bottom surface to create doped regions of different conductivity types, followed by annealing to form a uniformly distributed lightly doped drain, avoiding the use of ion implantation processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple ion implantation processes at various tilt angles are used to form lightly doped drain and halo implant regions, then the doping process can be completed, but the doping uniformity cannot meet the needs of high-end products
Solution Approach 1:
The dopant source layer is deposited in advance on the side surfaces and bottom surfaces of the recess before other processing steps. This preliminary deposition ensures that the dopant is already in position, and subsequent selective removal and annealing processes simply activate and distribute the pre-positioned dopant, achieving uniform doping without complex multi-angle ion implantation
Solution Approach 2:
The patent replaces the mechanical ion implantation process with a chemical deposition and thermal diffusion process. Instead of physically implanting ions at various angles, the dopant is deposited as a source layer and then thermally diffused during annealing, substituting mechanical bombardment with thermal energy-driven diffusion that naturally achieves uniform distribution
2Manufacturing precision
If conventional doping methods are used in three-dimensional fin structures, then the doping process can be completed, but uneven doping concentration occurs
Solution Approach 1:
The dopant source layer is selectively deposited only on the side surfaces and bottom surfaces of the recess, not on the top surface. This local deposition ensures that dopant is concentrated exactly where needed in the three-dimensional fin structure, achieving uniform doping concentration in the critical regions while keeping the process simple
Solution Approach 2:
The conformal deposition process automatically ensures uniform thickness and coverage on the three-dimensional fin structure surfaces. The self-aligned nature of the process, where the dopant source layer conforms to the fin geometry, eliminates the need for complex alignment steps and achieves uniform doping without additional operational complexity
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 effectively prevents short-channel effects by ensuring uniform dopant concentration, enhancing control over current flow and improving transistor performance.
Implementation Method 1
annealing the dopant source layer so as to form a side doped region in the fin structure
Data Source
AI summary
A method of fabricating a semiconductor device includes the following steps: providing a semiconductor substrate having a fin structure thereon; forming a recess in the fin structure so that the semiconductor substrate is partially exposed from the bottom surface of the recess; forming a dopant source layer conformally disposed on side surfaces and a bottom surface of the recess; removing the dopant source layer disposed on the bottom surface of the recess until portions of the semiconductor substrate are exposed from the bottom surface of the recess; and annealing the dopant source layer so as to form a side doped region in the fin structure.