Core-Shell Nanowire Doping Profile for CMOS Integration
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Solution Overview
Problem
Current semiconductor nanowire FETs face challenges in achieving desired doping profiles due to limitations in aligning gate and source/drain components with in situ growth and conventional dopant implantation techniques, leading to suboptimal performance and increased parasitic capacitance.
Innovation Solution
A three-dimensional nanostructure with a core-shell configuration is developed, featuring a semiconductor core with a uniform dopant concentration along its longitudinal axis and a higher dopant concentration in the radial direction, achieved through lithographical and deposition techniques without dopant implantation, allowing for selective removal of the semiconductor shell to create differential doping profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If in situ growth with desired doping profile is used, then doping profile is achieved, but alignment precision of gate and source/drain components deteriorates
Solution Approach 1:
The nanowire is segmented into multiple sections along its longitudinal axis, with each section having a different doping concentration. This allows the doping profile to be precisely controlled during growth while maintaining the ability to align gate and source/drain components with the segmented structure, resolving the contradiction between doping profile precision and alignment precision.
Solution Approach 2:
The patent transitions from conventional planar doping approaches to a three-dimensional core-shell nanowire structure with radial and longitudinal doping gradients. This dimensional change enables precise doping profile control in multiple directions while providing clear alignment references for gate and source/drain components.
2Ease of manufacture
If conventional dopant implantation is used, then doping is achieved, but uniform doping profile in various depths deteriorates
Solution Approach 1:
Instead of implanting dopants into an existing nanowire from the outside, the patent inverts the approach by growing the nanowire with the desired doping profile already incorporated during the epitaxial growth process. This eliminates the alignment and uniformity problems associated with conventional implantation methods.
Solution Approach 2:
The doping profile is predetermined and incorporated during the nanowire growth process itself, rather than being added afterward through implantation. This preliminary action ensures uniform doping distribution in various depths from the outset, avoiding the limitations of post-growth doping methods.
3Reliability
If uniformly doped nanowire is used, then contact quality is improved, but transmission probability deteriorates
Solution Approach 1:
The nanowire is designed with spatially varying doping concentrations, where highly doped regions are located near metal contacts to ensure low contact resistance, and lightly doped or undoped regions are positioned in the channel area to maintain high carrier transmission probability. This local differentiation of doping quality resolves the contradiction between contact quality and transmission probability.
Data Source
AI summary
A semiconductor structure is provided, which includes multiple sections arranged along a longitudinal axis. Preferably, the semiconductor structure comprises a middle section and two terminal sections located at opposite ends of the middle section. A semiconductor core having a first dopant concentration preferably extends along the longitudinal axis through the middle section and the two terminal sections. A semiconductor shell having a second, higher dopant concentration preferably encircles a portion of the semiconductor core at the two terminal sections, but not at the middle section, of the semiconductor structure. It is particularly preferred that the semiconductor structure is a nanostructure having a cross-sectional dimension of not more than 100 nm.