Semiconductor device and manufacturing method thereof
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Solution Overview
Problem
As semiconductor technology advances to sub-20-25 nm nodes, gate-all-around (GAA) FETs face challenges in achieving optimal control over the channel region due to the lack of gate control over the bottom side of the fin structure in traditional designs, leading to short-channel effects and performance limitations.
Innovation Solution
The manufacturing process involves forming stacked semiconductor layers with varying Ge content, patterning them into fin structures, and using a sacrificial gate structure to create a fully surrounded gate dielectric and electrode layer around the channel region, ensuring comprehensive control and improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional Fin FET gate structure is used where the gate electrode is adjacent to three side surfaces of the channel region, then the manufacturing process is simpler, but the gate control over the channel region is insufficient leading to short-channel effects
Solution Approach 1:
The gate structure transitions from a planar configuration to a three-dimensional wrap-around structure that envelops the channel region on all sides including the bottom surface. This dimensional change enables complete gate control over the channel, eliminating short-channel effects while maintaining scalability to sub-20-25 nm nodes
Solution Approach 2:
The gate dielectric layer and gate electrode are nested around the channel region in a concentric arrangement, with the gate dielectric layer forming an inner layer directly surrounding the channel and the gate electrode forming an outer layer. This nested configuration achieves complete gate control through a structured, manufacturable design
2Productivity
If transistor dimensions are scaled down to sub 20-25 nm nodes to increase device density, then higher device density is achieved, but short-channel effects and performance limitations worsen
Solution Approach 1:
By transitioning to a three-dimensional gate-all-around structure, the patent maintains effective gate control even as transistor dimensions scale down to sub-20-25 nm nodes. The wrap-around gate configuration provides superior electrostatic control that counteracts the increased short-channel effects inherent in scaled devices, enabling continued density improvement without sacrificing reliability
Solution Approach 2:
The gate dielectric layer thickness and gate electrode dimensions are optimized for sub-20-25 nm nodes, with the gate dielectric layer forming a complete surrounding barrier that enhances depletion control. Material composition and layer thickness parameters are specifically tuned to maintain performance at scaled dimensions
Data Source
AI summary
A semiconductor device includes a first channel region disposed over a substrate, a first source region and a first drain region disposed over the substrate and connected to the first channel region such that the first channel region is disposed between the first source region and the first drain region, a gate dielectric layer disposed on and wrapping the first channel region, a gate electrode layer disposed on the gate dielectric layer and wrapping the first channel region, and a second source region and a second drain region disposed over the substrate and below the first source region and the first drain region, respectively. The second source region and the second drain region are in contact with the gate dielectric layer. A lattice constant of the first source region and the first drain region is different from a lattice constant of the second source region and the second drain region.