SiGe Fin Channel Profile Control to Reduce DIBL
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Solution Overview
Problem
Current semiconductor devices face challenges in achieving optimal channel region profiles, leading to increased drain-induced barrier lowering (DIBL) and device defects due to limitations in feature size reduction and material composition.
Innovation Solution
The formation of channel regions with gradient concentrations of semiconductor materials, specifically silicon germanium, where higher germanium concentrations at the bottom and lower concentrations at the top, are achieved through epitaxial growth and selective etching processes, resulting in more rectangular profiles and improved gate control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional fabrication methods are used to reduce minimum feature size, then integration density improves, but channel region profile control deteriorates leading to increased DIBL and device defects
Solution Approach 1:
The patent applies local quality by creating channel regions with gradient concentrations of semiconductor materials, specifically silicon germanium, where higher germanium concentrations are positioned at the bottom and lower concentrations at the top. This non-uniform material composition within the channel region provides better profile control and reduced DIBL while maintaining integration density improvements from feature size reduction.
Solution Approach 2:
The patent utilizes parameter changes by varying the germanium concentration throughout the channel region depth. The epitaxial growth process deposits silicon germanium with controlled gradient concentrations, and selective etching processes further modify the profile. These parameter changes in material composition enable precise control over channel region geometry and electrical characteristics, resolving the contradiction between integration density and profile control.
2Area of moving object
If feature size is reduced to increase integration density, then more components fit in given area, but DIBL and device defects increase due to profile control limitations
Solution Approach 1:
By implementing local quality through gradient silicon germanium concentrations in the channel region, the patent achieves better profile control at reduced feature sizes. The higher germanium concentration at the bottom provides structural stability and profile control, while the lower concentration at the top maintains electrical performance. This local differentiation reduces device defects and improves reliability despite increased integration density.
Solution Approach 2:
The patent employs composite materials by combining silicon and germanium in varying concentrations within the channel region. The silicon germanium alloy with gradient composition provides both the mechanical/structural benefits of germanium (profile control, reduced DIBL) and the electrical benefits of silicon, creating a composite structure that maintains reliability while enabling higher integration density through smaller feature sizes.
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 reduces DIBL, enhances performance, and minimizes device defects by providing better control over fin-width variation and gate control in semiconductor devices.
Implementation Method 1
The channel regions may be thinned by exposing the channel regions to alkaline or acid solutions
Implementation Method 2
The formation of channel regions with gradient concentrations of semiconductor materials, specifically silicon germanium, where higher germanium concentrations at the bottom and lower concentrations at the top, are achieved through epitaxial growth
Data Source
AI summary
Methods for improving profiles of channel regions in semiconductor devices and semiconductor devices formed by the same are disclosed. In an embodiment, a method includes forming a semiconductor fin over a semiconductor substrate, the semiconductor fin including germanium, a germanium concentration of a first portion of the semiconductor fin being greater than a germanium concentration of a second portion of the semiconductor fin, a first distance between the first portion and a major surface of the semiconductor substrate being less than a second distance between the second portion and the major surface of the semiconductor substrate; and trimming the semiconductor fin, the first portion of the semiconductor fin being trimmed at a greater rate than the second portion of the semiconductor fin.