GAA Semiconductor Structure With Metal Oxide Dopant Barriers
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Solution Overview
Problem
Conventional methods for manufacturing gate-all-around (GAA) devices face challenges such as dopant out-diffusion, leading to threshold voltage variation, increased minimum operating voltage, serious drain-induced barrier lowering, larger subthreshold leakage current, and degraded carrier mobility in SRAM and standard logic cells.
Innovation Solution
Incorporating metal oxide layers between semiconductor layers and inner spacers to act as a barrier and prevent dopant diffusion, thereby improving the characteristics of GAA devices by interposing rare earth oxides like lanthanum oxide, gadolinium oxide, or yttrium oxide between the semiconductor layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing methods are used for GAA devices, then manufacturing process is simpler, but dopant out-diffusion occurs causing threshold voltage variation and degraded device characteristics
Solution Approach 1:
A metal oxide layer is introduced as an intermediary barrier between the doped well region and the channel region. This metal oxide layer prevents dopant diffusion into the channel while allowing the manufacturing process to remain relatively straightforward, thus improving threshold voltage control without excessive complexity increase
Solution Approach 2:
The patent uses composite material structures combining semiconductor layers with metal oxide barrier layers. This composite approach creates a multi-layer structure where the metal oxide component provides dopant blocking functionality while the semiconductor layers maintain device operation, resolving the contradiction between precision and complexity
2Reliability
If metal oxide layers are added to prevent dopant diffusion, then device characteristics improve, but manufacturing process complexity increases
Solution Approach 1:
The metal oxide layer is applied locally only where dopant diffusion needs to be prevented (at the interface between doped regions and channel), rather than throughout the entire device structure. This localized approach improves reliability where needed while minimizing overall structural complexity
Solution Approach 2:
The metal oxide layer serves as a thin intermediary barrier that provides significant dopant blocking functionality with minimal added structural complexity. Its intermediate position between doped regions and channel allows it to prevent out-diffusion without requiring major structural redesign
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
The use of metal oxide layers results in improved threshold voltage variation, reduced minimum operating voltage, decreased subthreshold leakage current, and enhanced carrier mobility, with improvements ranging from 10% to 36% compared to GAA devices without these layers.
Implementation Method 1
metal oxide layers interposing between the inner spacers and the semiconductor layers
Data Source
AI summary
A semiconductor structure includes: a semiconductor substrate; a first source/drain feature and a second source/drain feature over the semiconductor substrate; and semiconductor layers extending longitudinally in a first direction and connecting the first source/drain feature and the second source/drain feature. The semiconductor layers are spaced apart from each other in a second direction perpendicular to the first direction. The semiconductor structure further includes inner spacers each between two adjacent semiconductor layers; metal oxide layers interposing between the inner spacers and the semiconductor layers; and a gate structure wrapping around the semiconductor layers and the metal oxide layers.