GAA Transistor Epitaxy Layout for Void-Free Source/Drain Isolation
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Solution Overview
Problem
The challenge of forming reliable semiconductor devices at smaller sizes is exacerbated by the increasing complexity of fabrication processes as feature sizes continue to decrease, making it difficult to maintain device performance and prevent defects.
Innovation Solution
The use of gate all around (GAA) transistor structures patterned through photolithography and self-aligned processes, combined with selective epitaxial growth and etching techniques to form epitaxial layers and dielectric structures that provide additional nucleation sites for source/drain epitaxial structures, ensuring void-free formation and electrical isolation, thereby improving device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency and cost are improved, but fabrication process difficulty and device reliability deteriorate
Solution Approach 1:
Epitaxial layers are formed in advance before source/drain structures are created. These pre-formed epitaxial layers serve as nucleation sites and structural templates that guide subsequent material deposition, ensuring proper crystal orientation and reducing defects even at scaled dimensions
Solution Approach 2:
Dielectric structures are introduced as intermediary elements positioned between and around the epitaxial layers. These dielectric structures provide electrical isolation, mechanical support, and process control during fabrication, enabling reliable device operation at smaller feature sizes
2Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency and cost are improved, but fabrication process complexity increases
Solution Approach 1:
The fabrication process is divided into distinct sequential stages: forming epitaxial layers first, then creating dielectric structures, and finally forming source/drain structures. This segmentation allows each step to be optimized independently and simplifies process control despite overall complexity
Solution Approach 2:
The patent utilizes changes in material properties and process parameters during epitaxial growth to achieve desired structures. By controlling deposition conditions, temperature, and composition, complex nanoscale structures are formed through controlled parameter variations rather than complex process sequences
3Ease of manufacture
If epitaxial layers are formed without dielectric structures, then manufacturing is simpler, but void formation occurs and electrical isolation is compromised
Solution Approach 1:
Dielectric structures serve as intermediary elements that fill spaces between epitaxial layers and source/drain structures. They prevent void formation by providing continuous material coverage and ensure electrical isolation between adjacent devices, maintaining manufacturing precision without excessive complexity
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 enables the fabrication of integrated circuits with improved device performance by preventing current leakage and maintaining structural integrity, enhancing the reliability of semiconductor devices at reduced sizes.
Implementation Method 1
selective epitaxial growth and etching techniques to form epitaxial layers and dielectric structures that provide additional nucleation sites for source/drain epitaxial structures
Implementation Method 2
gate all around (GAA) transistor structures patterned through photolithography
Data Source
AI summary
A semiconductor device includes a substrate. Semiconductor layers are stacked one above another over the substrate. A gate structure wraps around each of the semiconductor layers. Epitaxial layers are over the substrate and in contact with opposite ends of a bottommost one of the semiconductor layers. Source/drain epitaxial structures are over and in contact with the epitaxial layers, respectively. Dielectric structures vertically between the epitaxial layers and the respective source/drain epitaxial structures, respectively.