Conformal Doping in Multi-Gate Devices via Sidewall Spacer Diffusion
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Solution Overview
Problem
Conventional semiconductor manufacturing techniques face challenges in achieving highly conformal source/drain extension regions in advanced multi-gate devices, particularly at technology nodes smaller than 35 nm, due to deviations in gate overlap and doping profile abruptness, which affect device performance and reliability.
Innovation Solution
The approach involves forming sidewall spacers with specific dopants that match the conductivity type of the source/drain extension regions, ensuring a consistent dopant concentration across the spacer and extension regions, achieved through a process that includes deposition and thermal annealing to diffuse dopants into the semiconductor material, thereby maintaining conformity and control over the doping profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If implantation techniques are used to form source/drain extension regions, then doping can be achieved, but gate overlap definition and doping profile abruptness deteriorate at advanced technology nodes
Solution Approach 1:
Dopants are incorporated into the sidewall spacer material during the deposition process itself, before the spacer is formed. This preliminary incorporation ensures that dopants are precisely positioned where needed and will diffuse only to the extent controlled by the spacer geometry, achieving both sharp profiles and consistent gate overlap
Solution Approach 2:
The sidewall spacer acts as an intermediary structure that carries dopants from the deposition step to the diffusion step. The spacer material serves as a temporary repository for dopants, releasing them in a controlled manner during thermal annealing to achieve the desired extension region doping with precise spatial control
2Manufacturing precision
If conventional deposition and diffusion processes are incorporated into existing process flows, then source/drain extension regions can be formed, but integration complexity and thermal budget increase
Solution Approach 1:
The deposition of sidewall spacer material and the incorporation of dopants into that material are merged into a single deposition step. This combination eliminates the need for separate doping and spacer formation processes, reducing overall process complexity while maintaining conformal doping profiles
Solution Approach 2:
The process utilizes standard thermal annealing parameters (temperature and time) that are already employed in conventional semiconductor manufacturing. By keeping the diffusion conditions within established parameter ranges, the process integrates smoothly into existing process flows without requiring additional thermal budget or complex process sequencing
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 method allows for the formation of highly conformal source/drain extension regions with improved gate overlap and doping profile abruptness, enhancing the reliability and performance of semiconductor devices by avoiding implantation-related crystal damage and shadowing effects, especially in multi-gate configurations.
Implementation Method 1
applying a thermal annealing process to diffuse dopants incorporated into a dielectric material of sidewall spacers into underlying extension regions
Data Source
AI summary
A semiconductor device includes a semiconductor material positioned above a substrate and a gate structure positioned above a surface of the semiconductor material, the gate structure covering a non-planar surface portion of the surface. A sidewall spacer is positioned adjacent to the gate structure and includes first dopants having one of an N-type and a P-type conductivity, wherein the sidewall spacer covers an entire sidewall surface of the gate structure and partially covers the surface of the semiconductor material. Source/drain extension regions that include the first dopants are positioned within the non-planar surface portion and in alignment with the sidewall spacer, wherein a concentration of the first dopants within a portion of the sidewall spacer proximate the non-planar surface portion substantially corresponds to a concentration of the first dopants within the source/drain extension regions proximate the non-planar surface portion.