Carbon-Doped Semiconductor Material for Source Drain Doping Profile Control
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Solution Overview
Problem
The existing methods for controlling the doping profile in field effect transistors, particularly through thermal dopant diffusion from raised source and drain regions, are limited in their ability to tailor the doping profile effectively, leading to trade-offs in performance parameters such as on-current, off-current, threshold voltage, and sub-threshold voltage slope.
Innovation Solution
The use of carbon-doped semiconductor material portions formed by selective epitaxy or shallow implantation, which retard dopant diffusion from raised source and drain regions, allowing for local tailoring of the doping profile by creating carbon-doped layers on underlying semiconductor surfaces and patterning them to form raised source and drain regions, thereby controlling the dopant distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal dopant diffusion from raised source and drain regions is used to control doping profile, then dopant distribution can be modified, but the doping profile is limited by geometry and diffusion parameters resulting in trade-offs in performance parameters
Solution Approach 1:
The patent introduces carbon-doped semiconductor material portions at specific locations between the raised source/drain regions and the channel. These carbon-doped portions create localized regions with different dopant diffusion characteristics, enabling independent control of doping profiles in different areas. This resolves the contradiction by allowing tailored doping profiles without being constrained by the global geometry and diffusion parameters alone.
Solution Approach 2:
The carbon-doped semiconductor material portions act as intermediary layers between the raised source/drain regions and the underlying semiconductor material. These intermediary portions control the dopant diffusion process by retarding dopant diffusion through the carbon-doped regions, thereby enabling precise control of the doping profile in the channel region without directly modifying the raised source/drain geometry.
2Manufacturing precision
If carbon-doped semiconductor material portions are introduced to retard dopant diffusion, then local tailoring of doping profile is enabled, but additional manufacturing steps are required
Solution Approach 1:
The patent combines the carbon doping step with the existing raised source/drain formation process. The carbon-doped semiconductor material portions are formed during the same epitaxial growth or implantation process that creates the raised source/drain regions, merging two functions into a single integrated process step. This reduces the overall device complexity while maintaining the benefit of precise doping profile control.
Solution Approach 2:
The carbon-doped semiconductor material portions serve multiple functions: they act as diffusion barriers to control dopant distribution, they modify the electrical characteristics of the underlying region, and they can serve as part of the final device structure. This multi-functionality justifies the additional processing by providing multiple benefits from a single added step.
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 enables precise alteration of device parameters by retarding dopant diffusion, resulting in improved performance characteristics without degrading other parameters, allowing for more tailored doping profiles in field effect transistors.
Implementation Method 1
The carbon-doped semiconductor material portions locally retard dopant diffusion from the raised source and drain regions into the underlying semiconductor material regions
Implementation Method 2
Carbon-doped semiconductor material portions can be formed by selective epitaxy of a carbon-containing semiconductor material layer
Implementation Method 3
Carbon-doped semiconductor material portions can be formed by shallow implantation of carbon atoms into surface portions of the underlying semiconductor surfaces
Data Source
AI summary
Carbon-doped semiconductor material portions are formed on a subset of surfaces of underlying semiconductor surfaces contiguously connected to a channel of a field effect transistor. Carbon-doped semiconductor material portions can be formed by selective epitaxy of a carbon-containing semiconductor material layer or by shallow implantation of carbon atoms into surface portions of the underlying semiconductor surfaces. The carbon-doped semiconductor material portions can be deposited as layers and subsequently patterned by etching, or can be formed after formation of disposable masking spacers. Raised source and drain regions are formed on the carbon-doped semiconductor material portions and on physically exposed surfaces of the underlying semiconductor surfaces. The carbon-doped semiconductor material portions locally retard dopant diffusion from the raised source and drain regions into the underlying semiconductor material regions, thereby enabling local tailoring of the dopant profile, and alteration of device parameters for the field effect transistor.