Gate Electrode Barrier for Semiconductor Threshold Voltage Stability
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Solution Overview
Problem
Conventional semiconductor fabrication methods can affect the threshold voltage of transistors due to direct contact between reactants and gate dielectric layers, leading to performance issues in semiconductor structures.
Innovation Solution
A method is developed where a gate electrode completely covers the gate dielectric layer, preventing reactants from the second dielectric layer formation from contacting the gate dielectric layer, thereby reducing oxygen atom diffusion and maintaining the threshold voltage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gate dielectric layer is formed on the sidewall surface of the opening, then the gate structure can be formed, but oxygen atoms from the second dielectric layer formation reactants can diffuse into the gate dielectric layer, affecting the threshold voltage
Solution Approach 1:
The gate electrode serves as an intermediary barrier between the second dielectric layer formation reactants and the gate dielectric layer. By forming the gate electrode on the gate dielectric layer to fill the opening, the patent prevents oxygen atoms from the reactants from directly contacting and diffusing into the gate dielectric layer, thus protecting the threshold voltage stability while allowing the gate structure to function properly
2Reliability
If the gate electrode fills the opening completely, then reactants are blocked from contacting the gate dielectric layer, but the fabrication process complexity increases
Solution Approach 1:
The patent applies preliminary action by forming the gate electrode on the gate dielectric layer before forming the second dielectric layer. This sequence ensures that the gate electrode is already in place to block oxygen atom diffusion when the second dielectric layer is formed, preventing threshold voltage issues without requiring complex additional 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 performance of semiconductor structures by minimizing the impact of oxygen atoms on the gate dielectric layer, ensuring stable threshold voltage and improved device performance.
Implementation Method 1
The gate electrode can completely cover the gate dielectric layer in the opening, and the subsequently-used reactants for forming the second dielectric layer are not easily be in contact with the gate dielectric layer. Thereby, the diffusion of the oxygen atoms from the reactants to the gate dielectric layer can be suppressed
Data Source
AI summary
A semiconductor structure and a fabrication method are provided. The fabrication method includes forming a first dielectric layer on a base substrate, the first dielectric layer containing an opening exposing a surface portion of the base substrate; forming an initial gate dielectric layer on the surface portion of the base substrate and on a sidewall surface of the opening in the first dielectric layer; forming a gate dielectric layer by removing a portion of the initial gate dielectric layer from the sidewall surface of the opening, such that a top surface of the gate dielectric layer on the sidewall surface is lower than a top surface of the first dielectric layer; forming a gate electrode on the gate dielectric layer to fill the opening, a portion of the gate electrode being formed on a portion of the sidewall surface of the first dielectric layer; and forming a second dielectric layer on the gate electrode and on the first dielectric layer.