Gate Dielectric Integration in Semiconductor Devices
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Solution Overview
Problem
The integration of a gate last process with multiple gate oxide configurations in semiconductor devices, such as system-on-a-chip (SOC) designs, is challenging due to the need for replacing polysilicon gate electrodes with metal gates while maintaining device performance and compatibility with existing fabrication processes.
Innovation Solution
A method is described for fabricating a semiconductor device using a gate last methodology, involving the formation of different gate dielectric layers on a substrate with regions having distinct configurations, followed by the deposition of a dummy gate, its removal, and the subsequent formation of a metal gate electrode, allowing for the integration of various gate dielectric materials and stack-ups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gate last process is used to replace polysilicon gate electrodes with metal gates, then device performance is improved, but integration with multiple gate oxide configurations becomes challenging
Solution Approach 1:
The substrate is divided into multiple device regions (first, second, and third regions) where different gate dielectric configurations are formed in each region. This segmentation allows each region to have optimized gate structures tailored to specific performance requirements while maintaining compatibility with the gate last process flow.
Solution Approach 2:
Different gate dielectric materials and stack-ups are implemented in different device regions based on local performance requirements. For example, high-k dielectric layers are formed in specific regions where enhanced performance is needed, while other regions may use different configurations, allowing localized optimization without compromising the entire device structure.
2Adaptability or versatility
If different gate dielectric configurations are formed on the same device, then device versatility is improved, but process integration difficulty increases
Solution Approach 1:
Dummy gate structures are formed preliminarily across all device regions before the gate last process. These dummy gates serve as placeholders that allow subsequent processing steps to be performed uniformly across the entire substrate, including the formation of different gate dielectric configurations in different regions, without requiring region-specific processing sequences.
Solution Approach 2:
The gate last process methodology is designed to be universal and applicable to multiple gate oxide configurations simultaneously. The same high-k dielectric layer formation and metal gate electrode deposition steps can be applied across all device regions regardless of the specific gate dielectric configuration present in each region, simplifying process integration.
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 enables a simple and cost-effective integration of gate structures with different gate dielectric materials and stack-ups, facilitating the transition from polysilicon to metal gate electrodes while maintaining device performance and compatibility with existing processes.
Implementation Method 1
A first gate dielectric layer is formed in a first device region
Implementation Method 2
A second gate dielectric layer is formed in a second device region
Implementation Method 3
A high-k gate dielectric layer is formed in a third device region
Implementation Method 4
The dummy gate structure is removed
Data Source
AI summary
A method of fabricating a semiconductor device having a different gate structure in each of a plurality of device regions is described. The method may include a replacement gate process. The method includes forming a hard mask layer on oxide layers formed on one or more regions of the substrate. A high-k gate dielectric layer is formed on each of the first, second and third device regions. The high-k gate dielectric layer may be formed directly on the hard mask layer in a first and second device regions and directly on an interfacial layer formed in a third device region. A semiconductor device including a plurality of devices (e.g., transistors) having different gate dielectrics formed on the same substrate is also described.