VGAA Gate Structure With Full Channel Encirclement
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Solution Overview
Problem
Existing vertical gate-all-around (VGAA) transistors face limitations in achieving optimal control of charge carriers and reducing short channel effects due to inadequate encirclement of the channel region by gate dielectric and electrode layers, leading to suboptimal performance in advanced semiconductor integrated circuits.
Innovation Solution
A manufacturing method involving the formation of a channel structure, hard mask layer, and sequential deposition of spacer, interfacial, high-k dielectric, and gate metal layers, followed by etching and patterning to create a gate structure that fully encircles the channel region, enhancing control over charge carriers and reducing short channel effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing VGAA transistor structures are used, then fabrication is relatively simple, but control of charge carriers is inadequate and short channel effects are not sufficiently reduced
Solution Approach 1:
The gate structure is designed with nested concentric layers including inner gate electrode, outer gate electrode, and surrounding gate dielectric layers that completely encircle the channel region. This nested configuration enables enhanced control of charge carriers through multiple gate layers while maintaining a systematic fabrication process using sequential deposition and etching steps
2Reliability
If existing VGAA transistor structures are used, then manufacturing process is straightforward, but short channel effects are not adequately reduced
Solution Approach 1:
The nested concentric gate structure with inner and outer gate electrodes completely surrounding the channel region provides superior electrostatic control that effectively suppresses short channel effects. The sequential fabrication process using deposition and etching steps makes this complex structure manufacturable
Solution Approach 2:
The gate structure transitions from planar or partial surround configurations to complete three-dimensional encirclement of the channel region. This dimensional enhancement provides superior control over charge carriers and short channel effects while maintaining fabrication feasibility through standardized deposition and etching processes
3Reliability
If complete encirclement of channel region is achieved, then control of charge carriers is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The fabrication process uses preliminary patterning steps to define mandrel structures before depositing gate dielectric and gate electrode layers. This preliminary action establishes precise geometric boundaries that guide subsequent deposition processes, ensuring complete and uniform encirclement of the channel region while managing manufacturing precision requirements
Solution Approach 2:
The sequential deposition of gate dielectric and gate electrode layers automatically conforms to the underlying channel structure geometry, creating self-aligned encirclement. This self-service mechanism reduces the need for high-precision lithographic patterning and ensures complete coverage through conformal deposition processes
Data Source
AI summary
A semiconductor device includes a channel region, first and second S/D contacts, first and second S/D epitaxial regions, a gate structure, and a gate contact. The channel region includes a first surface, a second surface opposite to the first surface, and a sidewall connected to the first surface and the second surface. The first S/D contact is disposed over the first surface of the channel region, the second S/D contact is disposed underneath the second surface of the channel region, the first S/D epitaxial region underlies the first S/D contact and overlies the first surface of the channel region, and the second S/D epitaxial region overlies the second S/D contact and underlies the second surface of the channel region. The gate structure surrounds the sidewall of the channel region, and the gate contact is disposed in proximity to the second S/D contact and lands on the gate structure.