Metal-Containing Bottom Isolation Structure for Heat and Leakage Control
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Solution Overview
Problem
The challenge of forming reliable semiconductor devices at smaller sizes is exacerbated by the complexity of fabrication processes as feature sizes continue to decrease, necessitating improved methods for patterning and isolation structures in semiconductor devices.
Innovation Solution
The formation of FinFET structures with fins and gate all around (GAA) transistor structures, utilizing a combination of photolithography and self-aligned processes for patterning, and the use of metal-containing dielectric materials to enhance heat dissipation and reduce leakage current through the implementation of isolation structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency and cost are improved, but fabrication process complexity and difficulty increase
Solution Approach 1:
The patent segments the fabrication process into multiple distinct stages: forming recesses in the substrate, depositing first and second dielectric layers with different etch selectivities, patterning using mandrels, and selective removal steps. This segmentation allows each stage to be optimized independently, managing the overall process complexity while enabling continued scaling to smaller feature sizes
Solution Approach 2:
The patent employs preliminary actions by pre-forming recesses in the substrate before depositing dielectric layers, and by using mandrel structures that are removed later to create patterns. These preliminary structures guide subsequent processing steps, making the overall fabrication more controllable and less complex despite small feature dimensions
2Ease of manufacture
If conventional isolation structures are used in scaled devices, then manufacturing is simpler, but heat dissipation is insufficient and leakage current increases
Solution Approach 1:
The patent uses a composite isolation structure consisting of two dielectric layers with different etch selectivities (first dielectric layer and second dielectric layer). This composite structure provides both mechanical isolation functionality and enhanced thermal management, while the differential etch selectivity enables precise patterning. The combination of materials achieves superior heat dissipation and leakage current reduction compared to conventional single-material isolation structures
Solution Approach 2:
The patent applies local quality by creating regions with different dielectric properties at specific locations. The first and second dielectric layers have different etch selectivities that are exploited locally during patterning, and the isolation structure is positioned specifically between fins to address local heat accumulation and leakage issues. This localized approach enhances reliability without requiring complete redesign of the entire fabrication process
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
The proposed method improves the reliability and performance of semiconductor devices by enhancing heat dissipation and reducing leakage current, thereby preventing temperature-induced operation shifts and extending device lifetime.
Implementation Method 1
metal-containing dielectric materials to enhance heat dissipation
Implementation Method 2
isolation structures... reducing leakage current
Data Source
AI summary
A semiconductor device structure and a formation method are provided. The method includes forming a sacrificial base layer over a substrate and forming a semiconductor stack over the sacrificial base layer. The semiconductor stack has multiple sacrificial layers and multiple semiconductor layers laid out alternately. The method also includes forming a gate stack to partially cover the sacrificial base layer, the semiconductor layers, and the sacrificial layers. The method further includes removing the sacrificial base layer to form a recess between the substrate and the semiconductor stack. In addition, the method includes forming a metal-containing dielectric structure to partially or completely fill the recess. The metal-containing dielectric structure has multiple sub-layers.