Fin Transistor Diffusion Doping for Uniform Source-Drain Junctions
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Solution Overview
Problem
The miniaturization of transistors leads to a short channel effect due to weakened gate control over channel current, causing leakage currents and performance issues, and ion implantation for doping results in lattice defects and uneven surface junction depths in FinFETs.
Innovation Solution
A method for manufacturing fin transistors involves forming a fin structure on a substrate, creating an isolation layer with the top surface lower than the fin, and using a diffusion process to dope the upper part of the fin for forming source and drain regions, which reduces lattice defects and achieves uniform surface junction depths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion implantation is used for doping to form source and drain regions in FinFET, then doping can be achieved, but lattice defects are caused and surface junction depth uniformity is affected
Solution Approach 1:
The patent replaces the mechanical ion implantation process with a chemical diffusion process. Instead of physically bombarding ions into the semiconductor lattice, the invention uses thermal diffusion where dopant atoms naturally diffuse into the silicon substrate through concentration gradients, eliminating mechanical damage and lattice defects while achieving uniform doping profiles
Solution Approach 2:
The patent changes the doping mechanism from ion implantation to diffusion by adjusting process parameters such as temperature and time. The diffusion process is controlled by maintaining specific temperature conditions that enable dopant atoms to diffuse uniformly into the fin structure without causing lattice damage, thereby improving both reliability and manufacturing precision
2Productivity
If transistor size is reduced to increase integration density, then component density increases, but gate control over channel current weakens causing short channel effect
Solution Approach 1:
The patent transitions from a planar transistor structure to a three-dimensional FinFET structure with vertical fins extending from the substrate. This dimensional change increases the effective channel width without increasing the planar footprint, allowing better gate control over the channel current while maintaining high integration density. The gate wraps around the fin structure, providing superior electrostatic control
Solution Approach 2:
The gate structure is nested around the vertical fin structure, with the gate surrounding the fin on three sides (top and two sidewalls). This nested configuration maximizes the gate's control over the channel current by enclosing the active region, thereby improving electrostatic control and reducing short channel effects while maintaining compact device dimensions
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 control over channel current, reduces leakage, and improves the performance of fin transistors by minimizing lattice defects and ensuring uniform doping, thereby enhancing the overall performance of the semiconductor device.
Implementation Method 1
Doping processing is performed on the upper part of the fin part by a diffusion process to form at least one of a source region or a drain region in the upper part of the fin part
Data Source
AI summary
A method for manufacturing a fin transistor structure includes the following: a substrate is provided, a fin part protruding from a top surface of the substrate; an isolation layer is formed on the substrate, a top surface of the isolation layer being lower than a top of the fin part, so that an upper part of the fin part is exposed above the isolation layer; and doping processing is performed on the upper part of the fin part by a diffusion process to form at least one of a source region or a drain region in the upper part of the fin part.