Silicon Germanium Oxide Interfacial Layer for High-K Dielectric Integration
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Solution Overview
Problem
The semiconductor industry faces challenges in implementing high-κ gate dielectric layers with interfacial layers in CMOS fabrication due to the consumption of soluble oxide materials by strong wet chemicals, which can lead to damage and inefficiencies in the formation process.
Innovation Solution
A method is introduced that involves forming a silicon germanium layer on a semiconductor substrate, creating dummy gate structures, and using a surface oxidation process with oxidizing gases to form an interfacial layer, which helps in reducing the consumption of germanium dioxide and maintaining a smooth surface, thereby preventing damage from wet chemicals and ensuring effective interface formation with high-κ dielectric layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If strong wet chemicals are used to form the interfacial layer, then the interfacial layer formation is enhanced, but soluble oxide material is consumed and damage occurs
Solution Approach 1:
The patent changes the chemical composition parameters of the interfacial layer by incorporating silicon oxide (SiO2) alongside germanium oxide (GeO2). This parameter modification creates a composite interfacial layer that maintains the beneficial properties of GeO2 while reducing its consumption through the protective and structural role of SiO2, thereby resolving the contradiction between interfacial layer quality and germanium dioxide consumption
Solution Approach 2:
The patent employs a composite interfacial layer structure consisting of multiple materials (SiO2 and GeO2) rather than a single material system. This composite approach allows the SiO2 component to protect the GeO2 from excessive consumption by wet chemicals while still forming a high-quality interfacial layer, thus addressing both the reliability improvement and substance loss reduction
2Productivity
If the thickness of the gate dielectric layer is reduced, then transistor performance is maintained with decreased gate length, but gate leakage increases
Solution Approach 1:
The patent changes the dielectric constant parameter by transitioning from traditional silicon oxide (κ≈3.9) to high-κ dielectric materials (κ>10). This parameter change enables the formation of a thinner physical gate dielectric layer that provides equivalent or superior electrical performance while maintaining lower gate leakage, as the higher dielectric constant compensates for the reduced thickness
Solution Approach 2:
The patent introduces a multi-layer gate dielectric structure with different material compositions (interfacial layer with SiO2/GeO2, high-κ dielectric layer, and optional barrier layer). This dimensional stratification allows each layer to perform specific functions: the interfacial layer provides smooth interface and damage protection, the high-κ layer provides low leakage and high capacitance, collectively resolving the contradiction between thinness and leakage
3Object-affected harmful factors
If high-κ dielectric layers are used, then gate leakage is reduced, but interface damage with silicon substrate occurs
Solution Approach 1:
The patent introduces an interfacial layer composed of SiO2 and GeO2 as an intermediary between the silicon substrate and the high-κ dielectric layer. This intermediary layer serves multiple protective functions: it prevents direct damaging contact between the high-κ dielectric deposition process and the silicon substrate, provides a smooth transition interface, and reduces stress concentration, thereby maintaining interface stability while enabling high-κ dielectric implementation
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 method effectively forms a high-quality interfacial layer with a smooth surface, maintaining the silicon-to-germanium ratio and preventing germanium dioxide loss, thus enhancing the performance and reliability of semiconductor devices by ensuring a stable and efficient interface between the silicon germanium layer and high-κ dielectric layers.
Implementation Method 1
a surface oxidation process with oxidizing gases to form an interfacial layer
Data Source
AI summary
A transistor includes a silicon germanium layer, a gate stack, and source and drain features. The silicon germanium layer has a channel region. The silicon germanium layer has a first silicon-to-germanium ratio. The gate stack is disposed over the channel region of the silicon germanium layer and includes a silicon germanium oxide layer over and in contact with the channel region of the silicon germanium layer, a high-κ dielectric layer over the silicon germanium oxide layer, and a gate electrode over the high-κ dielectric layer. The silicon germanium oxide layer has a second silicon-to-germanium ratio, and the second silicon-to-germanium ratio is substantially the same as the first silicon-to-germanium ratio.