Silicon Gate Stack Oxygen Diffusion Barrier
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Solution Overview
Problem
Conventional poly-silicon gates in semiconductor devices face issues such as boron penetration and depletion effects as device sizes scale down, leading to inferior performance and reduced processing yields due to oxygen diffusion into high-K gate dielectric layers.
Innovation Solution
A gate forming process that stacks silicon seed and silicon layers directly on a barrier layer, using different precursors to form an interface that traps oxygen atoms, thereby reducing their diffusion into the gate dielectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional poly-silicon is used as gate electrode, then manufacturing process compatibility is improved, but device performance deteriorates due to boron penetration and depletion effect
Solution Approach 1:
The patent changes the material parameter of the gate electrode from conventional poly-silicon to work function metals (such as titanium nitride, tantalum nitride, or tungsten), which have different electrical and chemical properties that eliminate boron penetration and depletion effects while maintaining process compatibility through integration with existing CMOS fabrication steps
Solution Approach 2:
The patent employs composite material structures including work function metals combined with high-K gate dielectric materials, and introduces barrier layers with specific compositions (such as titanium aluminum oxide or tantalum aluminum oxide) to create a multi-layer gate structure that simultaneously achieves improved electrical performance and process compatibility
2Reliability
If work function metals are used to replace poly-silicon gate, then gate control capability is improved, but oxygen diffusion into high-K gate dielectric layer worsens
Solution Approach 1:
The patent introduces barrier layers as intermediary structures between the work function metals and the high-K gate dielectric layer. These barrier layers (such as titanium aluminum oxide or tantalum aluminum oxide) act as mediators that prevent direct interaction between the metal and dielectric, thereby blocking oxygen diffusion pathways while maintaining the electrical functionality of the gate structure
Solution Approach 2:
The patent converts the potentially harmful oxygen diffusion mechanism into a beneficial process by controlling the formation of interfacial layers. The barrier layers are designed to allow controlled oxygen outgassing during fabrication while preventing subsequent oxygen diffusion into the high-K dielectric, thereby transforming a degradation mechanism into a protective feature
3Productivity
If device size is scaled down, then device density is improved, but processing yield deteriorates due to increased oxygen diffusion
Solution Approach 1:
The patent employs barrier layers as intermediary structures that scale with device dimensions. These layers maintain their protective function even as device sizes decrease, providing a consistent diffusion barrier that prevents oxygen-related degradation and maintains processing yield across different device scales
Solution Approach 2:
The patent uses thin film barrier layers with controlled thickness and composition that can be precisely deposited using atomic layer deposition (ALD) or chemical vapor deposition (CVD). These thin films provide effective oxygen diffusion barriers while occupying minimal space, enabling their integration into scaled-down device architectures without compromising processing yield
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 process effectively traps oxygen atoms, improving processing yields and reliability by reducing oxygen diffusion into the gate dielectric layer, which enhances the performance and stability of semiconductor devices.
Implementation Method 1
the silicon seed layer and the silicon layer must be formed by different precursors to form the interface. Therefore, dangling bonds can be formed at the interface to trap oxygen atoms from the barrier layer
Data Source
AI summary
A gate forming process includes the following steps. A gate dielectric layer is formed on a substrate. A barrier layer is formed on the gate dielectric layer. A silicon seed layer and a silicon layer are sequentially and directly formed on the barrier layer, wherein the silicon seed layer and the silicon layer are formed by different precursors.