Gate Electrode Work Function Tuning via Dopant Diffusion
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Solution Overview
Problem
As three-dimensional transistors shrink in size, their threshold voltage characteristics and gate dielectric reliability degrade, posing challenges in semiconductor device performance.
Innovation Solution
A method of forming a semiconductor device involves forming a gate dielectric, a conductive material layer, and a source material layer with a first element, where the element is diffused into the conductive material layer through thermal treatment to create a doped material layer with a different work function, and the source material layer is removed to prevent contact with the gate dielectric, ensuring the reliability and performance of the gate electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of three-dimensional transistors is decreased, then the integration density and miniaturization are improved, but the threshold voltage characteristic and gate dielectric reliability are degraded
Solution Approach 1:
The patent modifies the work function of the gate electrode by doping it with a first element (such as tungsten, molybdenum, or titanium) to adjust the electrical characteristics. This parameter change allows the transistor to maintain proper threshold voltage and performance even as the device size is reduced, thereby compensating for the reliability degradation that occurs with miniaturization.
Solution Approach 2:
The gate electrode is constructed as a composite structure comprising a base conductive material layer (such as tungsten or cobalt) and a doped material layer containing a first element. This composite material approach enables simultaneous optimization of electrical properties (work function, conductivity) and structural integrity, addressing the reliability issues that arise when scaling down transistor dimensions.
2Volume of moving object
If the size of three-dimensional transistors is decreased, then the integration density is improved, but the threshold voltage characteristic is degraded
Solution Approach 1:
By doping the gate electrode with a first element, the work function is adjusted to achieve the desired threshold voltage characteristic. This parameter modification counteracts the adverse effects of device scaling, allowing small transistors to maintain proper electrical characteristics and prevent threshold voltage degradation.
3Object-generated harmful factors
If a source material layer is formed on the conductive material layer and thermal treatment is performed, then the work function of the conductive material layer is changed, but the source material layer must be removed to prevent contact with the gate dielectric
Solution Approach 1:
The source material layer is used temporarily during the doping process to introduce the first element into the conductive material layer, then it is removed (taken out) to prevent contact with the gate dielectric. This extraction principle allows the work function to be adjusted while avoiding contamination or damage to the gate dielectric layer.
Solution Approach 2:
The source material layer is formed in advance (preliminary action) to enable doping of the conductive material layer before the gate dielectric is fully processed or to prepare the gate electrode with the desired work function prior to subsequent fabrication steps. This preliminary doping action simplifies later process steps.
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 threshold voltage characteristic and electrical resistance of the transistor while maintaining the integrity of the gate dielectric, improving the overall performance and reliability of the semiconductor device.
Implementation Method 1
diffusing the first element into the conductive material layer by performing a thermal treatment process
Implementation Method 2
diffusing the first element into the conductive material layer by performing a thermal treatment process
Data Source
AI summary
Provided are a semiconductor device having a gate and a method of forming the same. The method includes forming a gate dielectric, forming a first conductive material layer on the gate dielectric, forming a source material layer on the first conductive material layer, and diffusing a first element included in the source material layer into the first conductive material layer by performing a thermal treatment process to form a doped material layer.