Gate Electrode Protection Layer for Leakage Current Reduction
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Solution Overview
Problem
Conventional semiconductor devices, including MOS transistors and FinFETs, suffer from poor performance due to increased leakage current issues caused by the diffusion of doping ions like fluorine or chlorine, which induce a large offset in the threshold voltage, exacerbated by the high oxygen ion concentration in the second dielectric layer.
Innovation Solution
A semiconductor device fabrication method involving the formation of a compensating protective layer with a higher oxygen ionic concentration, which covers the entire top surface of the gate electrode, preventing direct contact between the gate electrode and the second dielectric layer, thereby reducing ion diffusion and leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a second dielectric layer with high oxygen ion concentration is formed on the gate electrode, then the gate electrode is protected from oxidation, but doping ions diffuse into the work function and gate dielectric layers causing threshold voltage offset
Solution Approach 1:
A protective layer with low oxygen ion concentration is introduced as an intermediary between the gate electrode and the second dielectric layer with high oxygen ion concentration. This intermediate layer prevents direct contact and blocks the diffusion path of doping ions, while still providing oxidation protection to the gate electrode. The protective layer acts as a mediator that resolves the contradiction between protection and precision.
Solution Approach 2:
The protective function is segmented into two distinct layers: a first protective layer in direct contact with the gate electrode having low oxygen ion concentration to prevent doping ion diffusion, and a second dielectric layer having high oxygen ion concentration for oxidation protection. This segmentation allows each layer to perform its specific function without causing harmful effects.
2Device complexity
If the gate electrode is exposed to reduce complexity, then the fabrication process is simplified, but leakage current increases due to ion diffusion
Solution Approach 1:
The protective layer serves as an intermediary that enables the gate electrode to remain exposed for simplified fabrication while simultaneously preventing the harmful diffusion of doping ions that would cause leakage current. The layer mediates between the need for process simplicity and the need to eliminate harmful effects.
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
The method effectively reduces the diffusion of doping ions into the work function and gate dielectric layers, minimizing threshold voltage offset and improving semiconductor device performance by preventing direct contact between the gate electrode and the second dielectric layer.
Implementation Method 1
A material of the first protective layer has a first oxygen ionic concentration and a material of the compensating protective layer has a second oxygen ionic concentration. A material of the second dielectric layer has a third oxygen ionic concentration. The first oxygen ionic concentration and the second oxygen ionic are smaller than the third oxygen ionic concentration.
Data Source
AI summary
A semiconductor device and fabrication method are provided. The method includes providing a first dielectric layer with a first groove on a base substrate. A first gate electrode is formed in the first groove, with a top surface lower than the first dielectric layer. A first protective layer is formed on a portion of the top surface of the first gate electrode, with a first oxygen ionic concentration. A compensating protective layer is formed on a remaining portion of the top surface of the first gate electrode exposed by the first protective layer, with a second oxygen ionic concentration. A second dielectric layer is formed on the first protective layer, on the compensating protective layer, and on the first dielectric layer, with a third oxygen ionic concentration. The first oxygen ionic concentration and second oxygen ionic concentration are smaller than the third oxygen ionic concentration.