Metal Bottom Isolation Structure for Heat Dissipation 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 due to decreasing feature sizes, which complicates the formation of FinFET structures and gate all around transistor structures.
Innovation Solution
The use of a semiconductor stack with alternating layers of different germanium concentrations for etching selectivity, combined with metal-containing dielectric materials and nitrogen-containing particles to enhance heat dissipation and reduce leakage current, is employed to form reliable semiconductor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency increases and costs decrease, but fabrication process complexity increases and manufacturing difficulty increases
Solution Approach 1:
The patent segments the fabrication process into multiple distinct stages: forming alternating semiconductor layers with different etch selectivities, selective removal of sacrificial layers, formation of isolation structures, and gate stack formation. This segmentation allows each step to be optimized independently, managing the overall process complexity while enabling continued scaling.
Solution Approach 2:
The patent applies local quality by using semiconductor layers with different germanium concentrations (e.g., 0% Ge in channel layers vs. 8% Ge in sacrificial layers) at specific locations. This creates etch selectivity differences that enable precise pattern transfer and feature formation at reduced dimensions without increasing overall process complexity.
2Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency increases and costs decrease, but reliability of semiconductor devices decreases
Solution Approach 1:
The patent performs preliminary actions by forming isolation structures before gate stack formation, and by using sacrificial layers that are removed selectively to create precise feature geometries. These preliminary steps ensure that subsequent processing steps can be performed reliably at smaller dimensions, maintaining device reliability while enabling continued scaling.
Solution Approach 2:
The patent uses intermediate sacrificial layers with different etch selectivities as mediators to transfer patterns from mandrels to final semiconductor structures. These intermediary layers enable precise feature formation at reduced dimensions without directly compromising the reliability of the final device structures.
3Temperature
If metal-containing dielectric materials and nitrogen-containing particles are used to enhance heat dissipation, then temperature-induced operation shifts are prevented, but device structure complexity increases
Solution Approach 1:
The patent employs composite isolation structures combining metal-containing dielectric materials (such as tungsten oxide or molybdenum oxide) with nitrogen-containing particles or layers. This composite approach enhances thermal conductivity and heat dissipation capabilities while managing the increased structural complexity through integrated formation processes.
Solution Approach 2:
The patent modifies the thermal and compositional parameters of isolation structures by incorporating metal-containing dielectric materials and nitrogen-containing species. These parameter changes enhance heat dissipation properties to prevent temperature-induced operation shifts, with the complexity managed through controlled material deposition and processing.
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 improves the heat dissipation and reduces leakage current, enhancing the performance and reliability of semiconductor devices by preventing temperature-induced operation shifts and lifetime degradation.
Implementation Method 1
metal-containing dielectric materials and nitrogen-containing particles to enhance heat dissipation
Implementation Method 2
semiconductor stack with alternating layers of different germanium concentrations for etching selectivity
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.