Carbon-Doped Gate Electrode for MIS Transistor Impurity Diffusion
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Solution Overview
Problem
MIS transistors face challenges in miniaturization and resistance reduction due to impurity diffusion issues, which affect threshold voltage and gate electrode resistance, particularly when impurities penetrate the gate insulating film and silicide layers.
Innovation Solution
The semiconductor device incorporates a gate electrode structure with C-doped layers around a polycrystalline silicon layer, where carbon concentrations of at least 1×10^20/cm^3 prevent impurity diffusion, and the thickness of these layers is set to 5 nm or less to maintain the polycrystalline silicon layer's integrity and reduce resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the gate electrode is miniaturized to improve transistor performance, then the device size is reduced, but impurity diffusion becomes more severe causing threshold voltage instability
Solution Approach 1:
A carbon-containing layer is introduced as an intermediary substance between the polycrystalline silicon layer and the impurity sources. This carbon layer acts as a diffusion barrier that prevents impurities from penetrating into the polycrystalline silicon, thereby stabilizing the threshold voltage while allowing the gate electrode to be miniaturized
2Device complexity
If the gate electrode structure is simplified to reduce manufacturing complexity, then the device complexity is reduced, but the gate electrode resistance increases
Solution Approach 1:
The carbon concentration in the carbon-containing layer is optimized to be at least 1×10^20/cm³. This specific parameter change ensures that the layer provides sufficient impurity diffusion barrier functionality while maintaining appropriate electrical resistance characteristics for the gate electrode operation
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 configuration effectively prevents impurity diffusion, stabilizes the threshold voltage, and reduces the resistance of the gate electrode, enhancing the performance of the MIS transistor.
Implementation Method 1
a C-doped layer which is provided around the polycrystalline silicon layer, and contains polycrystalline silicon and carbon
Data Source
AI summary
A semiconductor device includes a gate insulating film on a semiconductor substrate, and a gate electrode on the gate insulating film. The gate electrode includes a first layer containing polycrystalline silicon, a second layer between the first layer and the gate insulating film and containing polycrystalline silicon and carbon, a third layer on an upper surface of the first layer and containing polycrystalline silicon and carbon, a fourth layer on a first side surface of the first layer and containing polycrystalline silicon and carbon, and a fifth layer on a second side surface of the first layer and containing polycrystalline silicon and carbon.