GAA SiGe-Silicon Interface Engineering to Suppress Germanium Diffusion
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Solution Overview
Problem
The scaling down of silicon metal oxide semiconductor (MOS) devices is challenged by short channel effects, and current processes using chlorinated precursors are inadequate in suppressing germanium diffusion in SiGe layers, which affects device performance.
Innovation Solution
Incorporation of carbon-containing precursors during SiGe growth to suppress germanium diffusion, using organosilane, organogermane, or carbon-only containing precursors, followed by silicon channel growth, to enhance the superlattice structure in gate-all-around (GAA) transistor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chlorinated precursors are used during SiGe layer deposition, then the deposition process can proceed, but germanium diffusion is not sufficiently suppressed
Solution Approach 1:
A carbon-containing precursor layer is introduced as an intermediary between the SiGe layer and the silicon channel layer. This carbon layer acts as a diffusion barrier that prevents germanium from diffusing into the silicon channel, thereby suppressing germanium diffusion while maintaining interface abruptness. The carbon precursor is deposited during the SiGe growth process, creating a controlled interface structure.
Solution Approach 2:
The deposition process parameters are changed by introducing carbon-containing precursors (such as methylsilane, dimethylsilane, ethylsilane, diethylsilane, methyldisilane, dimethyldisilane, hexamethyldisilane, methane, ethane, acetylene, ethylene, propylene, propane, hexane, benzene, isoprene, or butadiene) during specific stages of the deposition cycle. This changes the chemical composition at the interface, creating a carbon-enriched layer that suppresses germanium diffusion without compromising the overall device performance.
2Productivity
If transistor dimensions are scaled down to smaller technology nodes, then production efficiency improves and costs decrease, but short channel effects increase
Solution Approach 1:
The carbon-containing precursor layer serves as a mediator at the SiGe-silicon interface, preventing germanium diffusion into the silicon channel. This is particularly important in scaled-down devices where short channel effects are more pronounced, as it maintains sharper interfaces and better gate control, thereby reducing short channel effects while allowing continued miniaturization.
Solution Approach 2:
The carbon doping is applied locally at the SiGe-silicon interface rather than throughout the entire structure. This localized modification creates a diffusion barrier precisely where needed (at the interface) without affecting the bulk properties of the SiGe or silicon layers, enabling continued scaling while maintaining device performance.
3Manufacturing precision
If carbon-containing precursors are added during SiGe growth, then germanium diffusion is suppressed, but the deposition process complexity increases
Solution Approach 1:
The carbon-containing precursor deposition is merged with the existing SiGe deposition process. The carbon precursor is introduced during specific stages of the deposition cycle (along with silicon and germanium precursors), combining multiple functions into a single integrated process rather than requiring separate deposition steps. This reduces overall process complexity while achieving the desired carbon enrichment at the interface.
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 method effectively suppresses germanium diffusion to SIMS detection levels, improving device performance and reducing short channel effects in GAA transistors.
Implementation Method 1
Incorporation of carbon-containing precursors during SiGe growth to suppress germanium diffusion
Implementation Method 2
repeating the deposition cycle to prepare a multi-layered epitaxial stack including two or more of the carbon-doped silicon-germanium and silicon mini-stacks on the substrate
Implementation Method 3
exposing a workpiece including the substrate to a first gas including a silicon precursor, a silicon-chlorine precursor, a germanium precursor, and a carrier gas to deposit a silicon-germanium layer
Data Source
AI summary
Superlattice structures that may be used in gate-all around (GAA) transistor devices and methods for manufacturing the same are provided. In one or more implementations of the present disclosure, carbon-containing precursors are used to dose the SiGe surface prior to silicon channel growth to suppress germanium diffusion. The carbon-containing precursors can be selected from organosilane precursors, organogermane precursors, and carbon precursors. The carbon-containing precursor can be used with chlorinated precursors. The carbon-containing precursor can be flowed throughout the growth of the entire SiGe thickness. The carbon-containing precursor can be flowed toward the end of the growth of the SiGe thickness. The carbon-containing precursor can be flowed after growth of the SiGe thickness.