Multi-Gate Transistor Formation With Selective Sacrificial Deposition
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Solution Overview
Problem
The formation of extraneous oxide layers on semiconductor substrates during the manufacturing of nano-FETs can impact subsequent process steps and device performance, particularly when forming sacrificial materials in the gate-last process.
Innovation Solution
A nitrogen-containing plasma treatment is applied to the exposed surfaces of fins and nanostructures to make them less susceptible to the deposition of a sacrificial material layer, followed by a conformal deposition and selective etching to minimize the presence of sacrificial material on these surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a sacrificial material layer is deposited conformally on channel regions and fins, then the gaps between channel regions are filled to form sacrificial material structures, but extraneous oxide layers form on the exposed surfaces of fins and nanostructures impacting device performance
Solution Approach 1:
A surface treatment is applied to the exposed surfaces of fins and nanostructures before depositing the sacrificial material layer. This preliminary treatment modifies the surface properties to reduce the susceptibility of these surfaces to oxide layer formation during subsequent processing steps, thereby preventing the harmful effect before it occurs.
Solution Approach 2:
The surface treatment is applied selectively only to the exposed surfaces of fins and nanostructures that are adjacent to channel regions, while leaving other surfaces untreated. This creates local differentiation in surface properties, ensuring that oxide layer formation is suppressed only where it would be harmful, while maintaining normal oxidation behavior elsewhere.
2Productivity
If the minimum feature size is reduced to improve integration density, then more components can be integrated into a given area, but additional manufacturing problems arise including increased susceptibility to oxide layer formation
Solution Approach 1:
The surface treatment modifies the physical or chemical parameters of the fin and nanostructure surfaces, changing their reactivity toward oxidation. This parameter change allows the structures to maintain their small dimensions for high integration density while simultaneously reducing their susceptibility to harmful oxide layer formation.
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 reduces manufacturing defects and improves device performance by minimizing the impact of sacrificial material on critical dimensions and electrical properties of nano-FETs.
Implementation Method 1
A nitrogen-containing plasma treatment is applied to the exposed surfaces of fins and nanostructures to make them less susceptible to the deposition of a sacrificial material layer
Implementation Method 2
a conformal deposition and selective etching to minimize the presence of sacrificial material on these surfaces
Data Source
AI summary
Forming a semiconductor device includes forming over a surface of a fin a stack of channel regions separated by respective gaps and applying a surface treatment to sidewalls of the channel regions and to the surface of the fin thus causing the sidewalls of the channel regions and the surface of the fin to be less susceptible to deposition of a sacrificial material layer, relative to prior to the surface treatment, and depositing the sacrificial material layer on the channel regions and on the surface of the fin, wherein the surface treatment causes deposition of the sacrificial material to occur to a lesser extent on the sidewalls of the channel regions and the surface of the fin relative to the tops and bottoms of the channel regions, and etching back the sacrificial material layer to form sacrificial material structures within the respective gaps.