Inner Spacer Layout for GAA Transistors With Uniform Current Flow
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Solution Overview
Problem
The semiconductor industry faces challenges in forming reliable devices at increasingly smaller sizes due to the complexity of fabrication processes as feature sizes decrease, leading to difficulties in achieving uniform current flow and electrical resistance across nanostructures.
Innovation Solution
The formation of gate all around (GAA) transistor structures with inner spacers and stressor structures, where the inner spacers have varying widths and air voids to reduce parasitic capacitance and improve current uniformity, and the use of stressor structures with varying widths to adjust electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency increases and costs decrease, but fabrication process complexity increases and manufacturing reliability deteriorates
Solution Approach 1:
The fabrication process is divided into multiple self-aligned steps including forming first spacers, removing sacrificial material, forming second spacers, and selective removal. This segmentation allows complex nanostructure formation to be broken down into manageable steps that can be performed with existing lithography tools, maintaining manufacturing reliability while achieving smaller feature sizes
Solution Approach 2:
Sacrificial material is deposited and patterned in advance before the actual nanostructure formation. This preliminary action creates a template that guides subsequent spacer formation and material deposition, ensuring precise alignment and reducing fabrication complexity despite smaller feature dimensions
2Area of stationary object
If feature sizes decrease to increase functional density, then chip area utilization improves, but achieving uniform current flow and electrical resistance becomes more difficult
Solution Approach 1:
The spacer width is varied locally along the length of the nanostructure. First spacers have a first width and second spacers have a second width different from the first. This local variation in spacer dimensions allows precise control of electrical resistance and current flow uniformity at different positions, compensating for manufacturing variations in smaller features
Solution Approach 2:
The physical parameters of the spacer structure are changed to control electrical properties. By adjusting spacer width, material composition, and thickness, the electrical resistance and current flow characteristics are optimized. This parameter control enables uniform current flow even as overall feature sizes decrease
3Manufacturing precision
If inner spacers with varying widths are formed to improve current uniformity, then current flow uniformity improves, but device structure complexity increases
Solution Approach 1:
The spacer structures serve multiple functions: they define nanostructure dimensions, control electrical resistance, ensure self-alignment for subsequent processing steps, and manage stress distribution. This multi-functionality reduces the need for additional separate structures, maintaining relative simplicity while achieving precise current flow control
Solution Approach 2:
The device structure employs nested layers including sacrificial material, first spacers, second spacers, and nanostructures, where each layer is formed within and dependent on the previous layer. This nested arrangement allows complex functionality to be achieved through systematic layering rather than complicated single-step structures
Data Source
AI summary
A semiconductor device structure is provided. The semiconductor device structure includes a substrate having a base and a fin over the base. The semiconductor device structure includes a nanostructure over the fin. The semiconductor device structure includes a gate stack wrapping around an upper portion of the fin and the nanostructure. The semiconductor device structure includes an inner spacer between the fin and the nanostructure. The semiconductor device structure includes a film in the inner spacer. A first dielectric constant of the film is lower than a second dielectric constant of the inner spacer. The semiconductor device structure includes a low dielectric constant structure in the film.