FinFETs with Gradient Germanium Channels
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Solution Overview
Problem
Current methods for improving drive currents in Fin Field-Effect Transistors (FinFETs) face challenges in maintaining high germanium concentration during high-temperature process steps, as conventional processes involve temperatures that can degrade germanium-rich layers formed early in the fabrication process.
Innovation Solution
The method involves forming semiconductor fins with a dummy gate, removing it to create a recess, and then performing oxidation to condense germanium, increasing its concentration on the fin surfaces, followed by forming a replacement gate dielectric and electrode, ensuring the germanium-rich layers are formed after high-temperature processes are completed, thus maintaining their integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional high-temperature processes are used during FinFET fabrication, then manufacturing compatibility is maintained, but germanium-rich layers are degraded
Solution Approach 1:
The patent performs required action in advance by forming the germanium-rich layer at the beginning of the fabrication process, before any high-temperature steps are applied. This preliminary formation allows subsequent high-temperature processes to proceed without degrading the germanium layer, as the layer is already in its final configuration and protected from thermal damage.
2Productivity
If germanium concentration is increased in FinFET channels, then drive currents are improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the germanium layer formation with existing fabrication steps by forming the germanium-rich layer as part of the initial structure formation process. This integration allows the germanium concentration to be increased without adding separate, complex manufacturing steps, thereby improving drive current while maintaining manufacturing simplicity.
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 germanium concentration in FinFET channels, improving drive currents while being compatible with existing FinFET fabrication processes, avoiding degradation of germanium-rich layers at high temperatures.
Implementation Method 1
performing oxidation to condense germanium, increasing its concentration on the fin surfaces
Data Source
AI summary
A method includes forming a semiconductor fin, forming a dummy gate on a top surface and sidewalls of the semiconductor fin, and removing the dummy gate to form a recess. The semiconductor fin is exposed to the recess. After the dummy gate is removed, an oxidation is performed on the semiconductor fin to form a condensed germanium-containing fin in the recess, and a silicon oxide layer on a top surface and sidewalls of the condensed germanium-containing fin. The method further includes forming a gate dielectric over the condensed germanium-containing fin, and forming a gate electrode over the gate dielectric.