Gettering Layer for Semiconductor Gate Structure EOT Control
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Solution Overview
Problem
As technology nodes decrease, controlling the thickness of the interface layer between high-k gate dielectrics and substrates becomes critical, as it contributes to the equivalent oxide thickness (EOT) and can negatively impact transistor performance.
Innovation Solution
A method involving the formation of a gettering layer, which includes an oxygen-gettering dielectric or metal composition, to reduce the thickness of the interface layer by getting oxygen from the interface layer, thereby controlling the EOT and preventing its growth during subsequent processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an interface layer is formed between high-k gate dielectric and substrate, then the dielectric structure is stabilized, but the equivalent oxide thickness increases due to the additional layer thickness
Solution Approach 1:
The patent removes oxygen from the interface layer using a gettering layer, effectively extracting the harmful element that causes thickness increase. This reduces the interface layer thickness while maintaining the stabilizing structure, resolving the contradiction between structural stability and thickness control
Solution Approach 2:
The patent changes the chemical composition parameter of the interface layer by removing oxygen through gettering. This parameter change reduces the physical thickness of the interface layer while preserving its stabilizing function, thereby reducing EOT without compromising reliability
2Manufacturing precision
If the interface layer thickness is reduced to control EOT, then transistor performance improves, but the interface layer becomes more difficult to control during fabrication
Solution Approach 1:
The patent introduces a gettering layer as an intermediary component between the substrate and the high-k dielectric. This intermediary actively manages oxygen content, providing a mechanism to control interface layer thickness more precisely without increasing overall fabrication complexity
Solution Approach 2:
The gettering layer provides self-service by automatically absorbing excess oxygen from the interface layer during fabrication processes. This self-regulating mechanism simplifies thickness control by eliminating the need for extremely precise deposition control, as the gettering layer compensates for variations
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 effectively reduces the thickness of the interface layer, stabilizes the high-k dielectric layers, and maintains minimal re-growth of the interface layer, enhancing the control over the EOT and improving transistor performance.
Implementation Method 1
The gettering layer includes an oxygen gettering dielectric composition... The thickness of the interface layer is reduced, to a second thickness, by gettering oxygen from the interface layer to the gettering layer
Data Source
AI summary
A method is provided that allows for maintaining a desired equivalent oxide thickness (EOT) by reducing the thickness of an interfacial layer in a gate structure. An interfacial layer is formed on a substrate, a gate dielectric layer such as, a high-k gate dielectric, is formed on the interfacial layer. A gettering layer is formed on the substrate overlying the interfacial layer. The gettering layer may function to getter oxygen from the interfacial layer such that the interfacial layer thickness is decreased and/or restricted from growth.