Semiconductor Isolation Structure With Spacer Layout for Leakage Control
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Solution Overview
Problem
The challenge of forming reliable semiconductor devices at smaller sizes is exacerbated by the increasing complexity and difficulty of fabrication processes as feature sizes continue to decrease, necessitating improved manufacturing methods.
Innovation Solution
A method involving the formation of semiconductor fins with epitaxial source/drain structures and advanced gate structures, utilizing multi-patterning processes and materials like boron nitride for improved carrier mobility and reduced leakage, along with a sequence of deposition and etching steps to create a stable and functional semiconductor device.
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 reliability increase
Solution Approach 1:
The fabrication process is divided into multiple patterning steps (e.g., self-aligned dual patterning, self-aligned triple patterning) where each step creates a portion of the final pattern. This segmentation allows complex small-featured devices to be manufactured through manageable sequential steps, maintaining reliability while achieving high functional density.
Solution Approach 2:
Mandrel structures and spacer layers are formed in advance before the final pattern transfer. These preliminary structures serve as templates that guide subsequent etching steps, ensuring precise feature formation at reduced dimensions while maintaining process reliability through pre-planned pattern definition.
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:
Multiple patterning operations are merged into self-aligned processes where spacers automatically define the position of subsequent features. This merging reduces the need for separate alignment steps and photolithography operations, simplifying the overall fabrication process while maintaining the ability to create small-featured high-density devices.
Solution Approach 2:
The fabrication process utilizes self-aligned mechanisms where previously formed structures (mandrels, spacers) automatically serve as masks and alignment references for subsequent steps. This self-service approach eliminates the need for external alignment equipment and complex photolithography processes, reducing fabrication complexity while enabling high functional density.
3Ease of manufacture
If conventional materials and processes are used at smaller sizes, then manufacturing simplicity is maintained, but carrier mobility and leakage performance deteriorate
Solution Approach 1:
The material composition parameters are changed from conventional silicon-based semiconductors to group III-V compounds (GaAs, InP, GaInAs) and other advanced materials with superior carrier mobility. This parameter change enables high-performance transistor operation at reduced feature sizes while maintaining manufacturability through established epitaxial growth and fabrication processes.
Solution Approach 2:
Composite semiconductor structures are formed using multiple material layers including group III-V compounds, silicon-germanium (SiGe) source/drain regions, and various dielectric materials. These composite materials provide tailored electrical properties for high carrier mobility while managing stress and leakage, enabling reliable small-featured device fabrication.
Data Source
AI summary
A semiconductor device includes a substrate, a first transistor, and a second transistor. The first transistor includes a first gate structure, first gate spacers on opposite sidewalls of the first gate structure, and first and second epitaxial source/drain structures. The second transistor includes a second gate structure, second gate spacers on opposite sidewalls of the second gate structure, and third and fourth epitaxial source/drain structures. The semiconductor device includes a first isolation structure laterally between the second epitaxial source/drain structure and the third epitaxial source/drain structure. The semiconductor device includes spacers on opposite sidewalls of a top portion of the first isolation structure, in which the spacers are made of a same material as the first and second gate spacers, and a dielectric constant of the first isolation structure is lower than a dielectric constant of the spacers.