Source/Drain Double-Charge Doping for Lower Contact Resistance
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Solution Overview
Problem
Source/drain contact resistance is a limiting factor in transistor performance, particularly in field-effect transistors, as existing single-charge dopants have degeneracy limits and cannot sufficiently decrease the energy barrier at the semiconductor/metal interface.
Innovation Solution
The use of double-charge dopants, such as sulfur, selenium, or tellurium, either alone or in combination with single-charge dopants, is introduced in the source/drain regions to decrease the energy barrier and improve contact resistance by increasing the doping concentration to degenerate levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single-charge dopants are used in source/drain regions, then the doping process is simple and well-established, but the degeneracy limit prevents sufficient decrease in energy barrier at the semiconductor/metal interface
Solution Approach 1:
The patent changes the fundamental parameter of dopant charge state from single-charge to double-charge. This parameter change enables achieving higher doping degeneracy and lower contact resistance because double-charge dopants provide twice the charge carriers per dopant atom, effectively overcoming the degeneracy limit of single-charge dopants while maintaining the same doping concentration levels
Solution Approach 2:
The patent employs composite doping strategies where double-charge dopants are combined with single-charge dopants in the source/drain regions. This composite approach leverages the advantages of both dopant types: double-charge dopants provide high degeneracy and low contact resistance, while single-charge dopants provide well-established processing and complementary electrical properties
2Reliability
If double-charge dopants are used to decrease energy barrier and improve contact resistance, then contact resistance is reduced, but the doping process becomes more complex and less established
Solution Approach 1:
The patent incorporates double-charge dopants during the source/drain formation process itself, performing the doping action preliminarily before subsequent processing steps. This preliminary incorporation ensures that the beneficial low-contact-resistance properties are established early in the manufacturing flow, allowing subsequent steps to build upon this foundation without requiring additional complex doping operations
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 significantly reduces contact resistance at the source/drain interfaces, enhancing transistor performance by achieving higher doping degeneracy and improving electrical conductivity.
Implementation Method 1
The use of double-charge dopants, such as sulfur, selenium, or tellurium, either alone or in combination with single-charge dopants, is introduced in the source/drain regions to decrease the energy barrier and improve contact resistance by increasing the doping concentration to degenerate levels.
Data Source
AI summary
Techniques are disclosed for forming transistors including source and drain (S/D) regions employing double-charge dopants. As can be understood based on this disclosure, the use of double-charge dopants for group IV semiconductor material (e.g., Si, Ge, SiGe) either alone or in combination with single-charge dopants (e.g., P, As, B) can decrease the energy barrier at the semiconductor/metal interface between the source and drain regions (semiconductor) and their respective contacts (metal), thereby improving (by reducing) contact resistance at the S/D locations. In some cases, the double-charge dopants may be provided in a top or cap S/D portion of a given S/D region, for example, so that the double-charge doped S/D material is located at the interface of that S/D region and the corresponding contact. The double-charge dopants can include sulfur (S), selenium (Se), and/or tellurium (Te). Other suitable group IV material double-charge dopants will be apparent in light of this disclosure.