SiGe Fin Trimming and Silicon Capping Against Oxidation
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Solution Overview
Problem
Existing methods for addressing short-channel effects and threshold voltage tuning in semiconductor devices, particularly with silicon germanium-based channels, are not entirely satisfactory due to susceptibility to oxidation reactions that degrade device performance.
Innovation Solution
A method involving selective trimming of silicon and silicon germanium fins before capping with a silicon layer to achieve precise fin dimensions, combined with epitaxial growth of the silicon cap, to prevent oxidation and enhance device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicon germanium fins are used to address short-channel effects and threshold voltage tuning, then device performance is improved, but susceptibility to oxidation reactions increases which degrades device performance
Solution Approach 1:
A silicon-containing layer is deposited as an intermediary protective barrier between the silicon germanium fin and the oxidizing environment. This cap layer selectively protects the germanium-rich regions from oxidation while allowing the fin to maintain its electrical functionality. The cap acts as a mediator that prevents direct contact between oxygen and the oxidation-sensitive silicon germanium material.
Solution Approach 2:
The silicon-containing cap layer is deposited in advance before the device undergoes subsequent processing steps that could cause oxidation. By establishing this protective barrier beforehand, the method prevents oxidation from occurring during later fabrication processes, thereby maintaining the integrity and performance of the silicon germanium fin.
2Manufacturing precision
If existing trimming methods are used for silicon germanium fins, then fin formation is achieved, but precision and effectiveness of trimming are insufficient leading to degraded device performance
Solution Approach 1:
The silicon-containing cap layer is deposited on the fin structure before final trimming operations. This preliminary capping action establishes a reference surface that enables more precise subsequent trimming. The cap layer serves as a template that helps achieve the desired fin dimensions with higher precision, and any excess cap material can be uniformly removed after trimming to reveal precisely dimensioned fins.
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 improves the precision and effectiveness of fin trimming and capping, leading to enhanced device performance by preventing oxidation and maintaining desired fin dimensions, thus addressing the limitations of existing methods.
Implementation Method 1
susceptibility to oxidation reactions that degrade device performance
Implementation Method 2
epitaxial growth of the silicon cap
Data Source
AI summary
A semiconductor structure includes a SiGe fin protruding from a substrate, where the SiGe fin includes a top portion having a first sidewall and a second sidewall and a bottom portion having a third sidewall and a fourth sidewall, and where a first transition region connecting the first sidewall to the third sidewall and a second transition region connecting the second sidewall to the fourth sidewall each have a tapered profile extending away from the first sidewall and the second sidewall, respectively, and a Si-containing layer disposed on the top portion of the SiGe fin, where a portion of the Si-containing layer on the first transition region extends away from the first sidewall by a first lateral distance and a portion of the Si-containing layer on the second transition region extends away from the second sidewall by a second lateral distance that is different from the first lateral distance.