SiGe FinFET Carrier Mobility via Germanium Condensation
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Solution Overview
Problem
Conventional FinFET fabrication faces challenges in improving current performance due to issues with layout designs and carrier mobility in the channel region of silicon germanium epitaxial structures.
Innovation Solution
A semiconductor device with a silicon germanium layer uniformly distributed in a fin-shaped structure is formed by creating an epitaxial layer on a silicon-containing substrate and performing a germanium condensation process, allowing germanium to accumulate in the fin structures and substrate, thereby increasing carrier mobility and element performance through the higher lattice constant of the silicon germanium layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional FinFET fabrication layout designs are used, then the basic transistor structure is achieved, but the carrier mobility in the channel region is insufficient and element performance is limited
Solution Approach 1:
The patent applies local quality by introducing a silicon germanium layer specifically in the fin shaped structure region while keeping the substrate as silicon. This creates a localized material composition change that enhances carrier mobility in the channel region without altering the entire device structure. The silicon germanium layer is positioned precisely where mobility enhancement is needed, demonstrating local quality improvement.
Solution Approach 2:
The patent changes the material composition parameter by incorporating germanium into the silicon fin structure. This parameter change (from pure silicon to silicon germanium alloy) directly affects the lattice constant and carrier mobility. The germanium concentration is controlled to achieve desired mobility enhancement while maintaining structural integrity and compatibility with existing fabrication processes.
2Volume of moving object
If the fin shaped structure is scaled down to reduce device size, then the overlapping area between gate and fin is reduced, but the control over channel region and reduction of short channel effects are compromised
Solution Approach 1:
The patent uses composite materials by combining silicon substrate with silicon germanium fin structure. This composite structure allows the fin to maintain mechanical strength and structural integrity at scaled dimensions while the silicon germanium portion provides enhanced electrical properties. The combination enables smaller device size without sacrificing channel control or introducing excessive short channel effects.
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 solution effectively increases carrier mobility and improves element performance by stressing the channel region of semiconductor transistors, achieving enhanced current between the source and drain and reducing drain-induced barrier lowering and short channel effects.
Implementation Method 1
the epitaxial layer may react with oxygen to form an oxide layer
Implementation Method 2
the epitaxial layer may also experience condensation simultaneously, thereby driving the germanium inwardly into the fin shaped structures and the substrate
Data Source
AI summary
A semiconductor device includes a silicon substrate, a fin shaped structure and a shallow trench isolation. The fin shaped structure includes a top portion which protrudes from a bottom surface of the fin shaped structure and the fin shaped structure is directly disposed on the silicon substrate. The bottom surface of the fin shaped structure covers an entire top surface of the silicon substrate. The fin shaped structure further includes a silicon germanium (SiGe) layer extending within the fin shaped structure and occupying the whole top portion of the shaped structure. The fin shaped structure is a semiconductor fin shaped structure, and the material of the silicon substrate is different from the material of the silicon germanium layer The shallow trench isolation is disposed on the top portion and the bottom surface of the fin shaped structure.