Stacked Channel Gate Structure With Protected SiGe Source/Drain
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Solution Overview
Problem
The existing methods of manufacturing semiconductor devices with vertically stacked channels face the risk of damaging the source/drain layer during the removal of sacrificial patterns.
Innovation Solution
A semiconductor device design featuring channels with a source/drain layer composed of silicon-germanium epitaxial layers, including a first epitaxial layer with a lower germanium concentration and a protruding portion that contacts the gate structure, which is formed using selective epitaxial growth (SEG) to protect the layer from damage during the removal of sacrificial patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sacrificial patterns are removed to form gate structures, then device functionality is achieved, but source/drain layer damage occurs
Solution Approach 1:
A protective layer is formed over the source/drain layer before the sacrificial patterns are removed. This protective layer acts as a barrier that prevents damage to the source/drain layer during the removal process, while still allowing the sacrificial patterns to be etched away to form the gate structure.
Solution Approach 2:
The protective layer serves as an intermediary element between the sacrificial patterns and the source/drain layer. It allows the sacrificial patterns to be removed without directly exposing the source/drain layer to potential damage, thus mediating the interaction between these two components.
2Reliability
If selective epitaxial growth is used to form source/drain layer, then layer protection is achieved, but manufacturing complexity increases
Solution Approach 1:
Selective epitaxial growth is used to form the protective layer with specific material properties. By controlling parameters such as temperature, pressure, and gas flow during the epitaxial growth process, a protective layer with desired characteristics is created that protects the source/drain layer while managing the complexity of the manufacturing 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 design prevents damage to the source/drain layer while removing sacrificial patterns, ensuring the integrity and performance of the semiconductor device.
Implementation Method 1
selective epitaxial growth (SEG) to form a source/drain layer containing silicon-germanium
Data Source
AI summary
A semiconductor device including channels spaced apart from each other on a substrate; a gate structure extending on the substrate, the gate structure surrounding lower and upper surfaces and sidewalls of each of the channels; and a source/drain layer on the substrate, the source/drain layer contacting sidewalls of the channels and containing silicon-germanium, the source/drain layer including: a second epitaxial layer having a second germanium concentration; and a first epitaxial layer having a first germanium concentration smaller than the second germanium concentration, the first epitaxial layer covering a lower surface and sidewalls of the second epitaxial layer, wherein the first epitaxial layer includes a protruding portion that protrudes in the first direction and contacts the gate structure, and wherein the protruding portion has a facet that is not curved.