GAA Gate Structure With Backside Dielectric Cap for Leakage Isolation
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Solution Overview
Problem
Current semiconductor devices face challenges with current leakage issues between the gate structure and via under the source/drain feature, which affect the performance and efficiency of the semiconductor device.
Innovation Solution
The implementation of a cap layer under the gate structure in gate all around (GAA) transistor devices, specifically a backside dielectric cap, to prevent current leakage by providing isolation between the gate structure and the backside via, and using a combination of processes such as epitaxial growth, dielectric layer formation, and planarization techniques to ensure proper alignment and contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a backside dielectric cap is added under the gate structure, then current leakage is prevented and isolation is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
A backside dielectric cap is introduced as an intermediary layer between the gate structure and the substrate. This dielectric cap acts as a mediator that prevents direct electrical contact and potential leakage paths, while also serving as a planarization layer that simplifies subsequent processing steps.
Solution Approach 2:
The backside dielectric cap is formed before the gate structure is fully assembled and before source/drain contacts are created. This preliminary action ensures that isolation is established early in the process, preventing current leakage issues before they can manifest, and providing a stable foundation for subsequent manufacturing steps.
2Reliability
If a backside dielectric cap is added under the gate structure, then isolation between gate structure and backside via is improved, but manufacturing precision requirements increase
Solution Approach 1:
The backside dielectric cap serves multiple functions simultaneously: it provides electrical isolation, enables planarization of the substrate surface, and creates a defined interface for subsequent layer deposition. By consolidating these functions into a single layer, the design reduces the number of separate precision-critical interfaces that would otherwise need to be aligned.
Solution Approach 2:
The dielectric cap layer allows for adjustment of the gate-to-substrate distance and provides a controllable interface thickness. By optimizing this parameter, the design achieves sufficient isolation while maintaining manufacturability and reducing the stringency of alignment requirements for subsequent processing 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 configuration effectively prevents current leakage and enhances the performance of the semiconductor device by ensuring good isolation between the gate structure and the backside via, allowing for improved electrical connectivity and reduced operational issues.
Implementation Method 1
The implementation of a cap layer under the gate structure in gate all around (GAA) transistor devices, specifically a backside dielectric cap, to prevent current leakage by providing isolation between the gate structure and the backside via
Implementation Method 2
using a combination of processes such as epitaxial growth, dielectric layer formation, and planarization techniques
Data Source
AI summary
A semiconductor device includes a semiconductor layer, a gate structure, a source/drain epitaxial structure, a backside dielectric cap, and an inner spacer. The gate structure wraps around the semiconductor layer. The source/drain epitaxial structure is adjacent the gate structure and electrically connected to the semiconductor layer. The backside dielectric cap is disposed under and in direct contact with the gate structure. The inner spacer is in direct contact with the gate structure and the backside dielectric cap.