Doped SiGe Epitaxy for Selective Low-Temperature Source/Drain Deposition
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Solution Overview
Problem
Conventional methods face challenges in selectively depositing doped semiconductor materials with low contact resistance and at reduced temperatures, which are essential for advanced semiconductor device scaling.
Innovation Solution
A method for epitaxially growing boron- and gallium-doped silicon germanium layers using chlorine-free precursors and a carrier gas, allowing selective deposition on monocrystalline surfaces while avoiding preferential etching, and a cap-and-etch approach for thicker layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional deposition methods are used to deposit doped semiconductor material, then material can be deposited on substrate, but contact resistance is high and selective deposition is difficult
Solution Approach 1:
The patent uses different precursors for different group IV elements (silicon, germanium, tin) that have different reactivity and decomposition characteristics. This allows selective deposition on specific substrate areas by controlling precursor introduction and reaction conditions, achieving local quality variation for selective device formation
Solution Approach 2:
The patent employs multiple dopants (boron, gallium, indium) at varying concentrations to modify the electrical properties of deposited layers. By adjusting dopant concentration and type, the method achieves low contact resistance and high mobility in specific regions while maintaining manufacturing flexibility
2Manufacturing precision
If high temperature deposition is used to deposit doped semiconductor material, then material quality can be improved, but thermal budget is exceeded for advanced devices
Solution Approach 1:
The patent uses precursors with optimized decomposition temperatures that allow high-quality material deposition at lower temperatures (below 450°C). The specific precursor selection enables controlled decomposition and atomic layer formation without requiring high thermal energy input
Solution Approach 2:
The patent replaces thermal-driven deposition mechanisms with chemically-driven deposition using plasma-enhanced or molecular beam epitaxy techniques. This substitution allows precise atomic-layer control and high material quality at reduced temperatures by using chemical reactions rather than thermal diffusion
3Productivity
If chlorine-containing precursors are used for deposition, then deposition rate can be increased, but preferential etching occurs reducing material quality
Solution Approach 1:
The patent extracts chlorine from the precursor molecules and replaces it with hydrogen or other non-etching ligands. This removal of the harmful chlorine element eliminates preferential etching while maintaining high deposition rates through optimized precursor decomposition kinetics
Solution Approach 2:
The patent uses sacrificial organic ligands in precursors that decompose completely during deposition, leaving no harmful residues. These short-living organic groups serve as temporary carriers for the metal atoms, enabling high-rate deposition without the persistent etching effects of chlorine
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
Enables the formation of semiconductor layers with low contact resistance and high mobility, suitable for source and drain regions in semiconductor devices, particularly at reduced temperatures.
Implementation Method 1
a boron and gallium doped epitaxial silicon germanium layer is grown on the first surface
Implementation Method 2
introducing a silicon precursor, a germanium precursor, a boron precursor, and a gallium precursor into the reactor chamber
Data Source
AI summary
Methods and devices for epitaxially growing boron- and gallium-doped silicon germanium layers. The layers may be used, for example, as a p-type source and/or drain regions in field effect transistors.