Semiconductor Work Function Layer Doping for Threshold Voltage Tuning
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Solution Overview
Problem
The semiconductor industry faces challenges in tuning threshold voltages of transistors without degrading the gate-filling capability of metal gate electrode layers, particularly in achieving different threshold voltages for FinFETs and GAA FETs on a single substrate.
Innovation Solution
Doping dopants such as oxygen, fluorine, and nitrogen into work function layers to shift their work functions, allowing for adjustment of threshold voltages without varying the material or thickness of the work function layers, thereby enabling the fabrication of transistors with different threshold voltages on a single semiconductor substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If dopants are doped into work function layers to adjust threshold voltages, then threshold voltage tuning capability is improved, but gate-filling capability of metal gate electrode layers deteriorates
Solution Approach 1:
The patent applies local quality by selectively doping different regions of the work function layer with different dopant concentrations. Specifically, the work function layer is divided into first and second regions with different dopant concentrations, allowing different threshold voltages to be achieved in different transistor regions while maintaining uniform gate electrode structure and composition for consistent gate-filling capability across all devices.
2Adaptability or versatility
If different materials or thicknesses are used for work function layers to achieve different threshold voltages, then threshold voltage diversity is improved, but device complexity increases
Solution Approach 1:
The patent employs parameter changes by varying the dopant concentration in different regions of the work function layer rather than changing the material composition or layer thickness. This approach achieves different threshold voltages through a single controllable parameter (dopant concentration), maintaining uniform material and structure across all devices while enabling threshold voltage diversity, thereby simplifying the manufacturing process.
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 allows for improved performance and manufacturing yield by enabling the production of transistors with varied threshold voltages without compromising the gate-filling capability, and simplifies the manufacturing process by allowing the use of silicon as the active region for p-type transistors instead of silicon germanium.
Implementation Method 1
Doping dopants such as oxygen, fluorine, and nitrogen into work function layers to shift their work functions
Data Source
AI summary
A method for forming a semiconductor structure is provided. The method includes forming a first active region and a second active region, forming a first n-type work function layer and a first p-type work function layer along the first active region and the second active region, respectively, forming a semiconductor material along the first n-type work function layer and the first p-type work function layer, removing a first portion of the semiconductor material along the first p-type work function layer, thereby leaving a second portion of the semiconductor material as a first protection layer over the first n-type work function layer, and diffusing a dopant into the first p-type work function layer to form a doped p-type work function layer while the first protection layer blocks the dopant from diffusing into the first n-type work function layer.