Diamond Epitaxy Buffer Layer for Fin Surface Repair
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Solution Overview
Problem
Current pre-epitaxy processing of epitaxial seed fin surfaces often results in fin damage, leading to nodule formation and excessive boron dopant deposition, which can cause epitaxial growth delays and device shorting due to high boron dopant concentrations near the channel.
Innovation Solution
A semiconductor device fabrication method involving the formation of a buffer layer around the fin to repair damage and provide a seed layer for diamond epitaxy growth, which is subsequently merged with overgrowth to control dopant concentration and prevent shorting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If long pre-epitaxy processing with high boron dopant gas is used, then fin surface preparation is achieved, but nodule formation and excessive boron dopant deposition occur leading to device shorting
Solution Approach 1:
A buffer layer is introduced as an intermediary between the damaged fin and the subsequent epitaxial growth. This buffer layer absorbs the harmful effects of prolonged pre-epitaxy processing by providing a sacrificial layer that can be damaged without affecting the underlying fin structure, while still enabling controlled boron dopant deposition for junction formation.
Solution Approach 2:
The buffer layer is formed in advance before the main epitaxial growth process. This preliminary action allows the fin surface to be prepared and repaired beforehand, creating a controlled interface that prevents nodule formation during subsequent processing while maintaining the ability to deposit appropriate dopant concentrations.
2Manufacturing precision
If high boron dopant concentration is deposited near the channel, then junction formation is enhanced, but device shorting occurs due to excessive dopant
Solution Approach 1:
The buffer layer enables spatially differentiated dopant concentration control. By having the buffer layer in place, boron dopant can be deposited with high concentration locally at the buffer-fin interface where junction formation is needed, while the buffer layer prevents excessive dopant from reaching the channel region, thus achieving local quality optimization.
Solution Approach 2:
The buffer layer acts as a parameter control mechanism for dopant concentration distribution. It allows the dopant concentration profile to be sharply controlled - high concentration near the junction region for effective junction formation, and low concentration near the channel to prevent shorting - by changing the physical and chemical parameters at the buffer layer interface.
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 buffer layer repairs fin damage and provides a clean seed surface for diamond epitaxy, reducing the risk of shorting and allowing for tuned dopant concentrations for beneficial junction and silicide formation, thereby improving semiconductor device performance.
Implementation Method 1
forming diamond shaped epitaxy upon the buffer layer
Data Source
AI summary
A semiconductor structure includes a fin upon a semiconductor substrate. A clean epitaxial growth surface is provided by forming a buffer layer upon fin sidewalls and an upper surface of the fin. The buffer layer may be epitaxially grown. Diamond shaped epitaxy is grown from the buffer layer sidewalls. In some implementations, the diamond shaped epitaxy may be subsequently merged with surrounding dielectric. A dopant concentration of the surrounding dielectric may be higher than a dopant concentration of the diamond shaped epitaxy.