FinFET Active Fin Width Control via Sacrificial Oxide Rounding
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Solution Overview
Problem
The challenge in manufacturing semiconductor devices is to reduce threshold voltage variation and achieve desired driving current in fin-shaped field effect transistors (FinFETs) of 10 nm or less, as the short channel effect hinders performance enhancement through transistor size reduction.
Innovation Solution
A method involving the formation of a trench with active fins in a substrate, followed by the deposition of a sacrificial layer with lower oxygen permeability than silicon oxide, and subsequent heat treatments under oxidation and non-oxidation atmospheres to form sacrificial oxide layers, which helps in rounding the corners of the active fins and reducing their width, thereby controlling the threshold voltage and driving current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transistor size is reduced to enhance performance and integration density, then integration density and performance are improved, but short channel effect increases making it difficult to enhance performance
Solution Approach 1:
The patent transitions from planar transistors to three-dimensional FinFET structures by creating vertical fins in the substrate. This dimensional change increases the effective channel area without increasing the footprint, thereby improving integration density while maintaining better electrostatic control to mitigate short channel effects through the fin geometry.
2Power
If active fin width is reduced to improve device performance, then driving current and performance are enhanced, but threshold voltage variation increases
Solution Approach 1:
The patent performs preliminary oxidation of the active fin surfaces before gate formation to create a uniform oxide layer. This preliminary action prepares the surface with controlled characteristics, ensuring consistent threshold voltage across devices while maintaining the reduced fin width necessary for high driving current and performance.
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 effectively reduces the width of the active fins, stabilizes the threshold voltage, and enhances the driving current of FinFETs, addressing the short channel effect and achieving desired performance levels in nanoscale transistors.
Implementation Method 1
The forming the sacrificial oxide layer may include heat-treating the sacrificial layer and surfaces of the plurality of active fins
Implementation Method 2
removing the sacrificial oxide layer
Data Source
AI summary
A method for manufacturing a semiconductor device includes forming a trench defining a plurality of active fins in a substrate, forming a sacrificial layer on the plurality of active fins, forming a sacrificial oxide layer, and removing the sacrificial oxide layer. The forming the sacrificial oxide layer includes heat-treating the sacrificial layer and surfaces of the plurality of active fins.