SiC Gate Interface Passivation for Higher Channel Mobility
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Solution Overview
Problem
Semiconductor devices based on silicon carbide suffer from low electron mobility at the SiC/gate dielectric interface, leading to increased channel resistance and ON-resistance, which necessitates larger active areas and higher costs.
Innovation Solution
A method involving surface cleaning and passivation of the SiC substrate to prevent exposure to oxidizing atmospheres during dielectric layer formation, followed by deposition of a passivation layer or interface layer using non-oxidative processes, such as hydrogen or nitrogen oxide, to enhance the SiC/gate dielectric interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gate dielectric layers are grown on SiC substrate, then a functional gate structure is formed, but defects propagate at the semiconductor-dielectric interface resulting in decreased device performance
Solution Approach 1:
The patent applies preliminary action by performing surface cleaning and passivation treatments on the SiC substrate before dielectric layer formation. Specifically, the substrate surface is cleaned to remove contaminants and then passivated by forming a thin interface layer (such as silicon oxide or silicon nitride) prior to depositing the gate dielectric. This preliminary preparation prevents defect propagation during subsequent dielectric growth, thereby improving device performance while maintaining the functional gate structure.
Solution Approach 2:
The patent introduces an intermediary interface layer between the SiC substrate and the gate dielectric layer. This interface layer acts as a mediator that prevents direct interaction between the substrate and dielectric, thereby blocking defect propagation. The interface layer can be formed through controlled oxidation or nitridation processes, creating a buffer zone that improves the overall quality of the semiconductor-dielectric interface.
2Reliability
If nitridation anneal is performed to enhance interface mobility, then electron mobility improves, but mobility remains low compared to SiC bulk mobility requiring larger active area
Solution Approach 1:
The patent performs preliminary surface passivation by forming a controlled interface layer before dielectric deposition. This preliminary treatment creates a high-quality interface that enhances electron mobility from the outset, reducing the need for subsequent nitridation anneals. The interface layer preparation includes controlling oxidation and carbon contamination levels, which directly improves channel mobility and allows for smaller active areas while maintaining device performance.
Solution Approach 2:
The patent applies parameter changes by precisely controlling the composition and thickness of the interface layer. By adjusting parameters such as oxidation time, temperature, and atmosphere composition during interface layer formation, the patent optimizes electron mobility at the SiC/dielectric interface. This controlled parameter adjustment achieves mobility levels closer to SiC bulk mobility, reducing the required active area and associated manufacturing costs.
3Manufacturing precision
If oxidizing atmosphere is used during dielectric layer formation, then complete dielectric coverage is achieved, but native oxides and carbon clusters form on the cleaned surface
Solution Approach 1:
The patent performs preliminary surface cleaning to remove native oxides and carbon clusters before dielectric layer formation. This cleaning step creates a fresh, contamination-free surface that is then immediately passivated with a controlled interface layer. By performing this preliminary preparation in a controlled sequence, the patent ensures complete dielectric coverage without re-introducing contamination, as the passivated surface is less susceptible to oxidative damage during subsequent processing.
Solution Approach 2:
The patent introduces an intermediary interface layer that acts as a protective barrier between the cleaned SiC substrate and the oxidizing atmosphere during dielectric formation. This interface layer prevents direct oxidation of the substrate surface, blocking the formation of unwanted native oxides and carbon clusters. The intermediary layer allows dielectric material to be deposited uniformly while maintaining surface purity and preventing contamination.
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
Improves channel mobility, reducing channel resistance and ON-resistance without increasing the active area, thereby lowering costs and device size.
Implementation Method 1
cleaning a surface area of the semiconductor substrate by removing oxide species, carbon clusters, or other contaminants
Implementation Method 2
Surface passivation may comprise any protection of the surface of the semiconductor substrate by passivation means such as, for example, a passivation layer or passivation components which are suitable for protecting the SiC substrate surface from reacting with oxidizing components
Implementation Method 3
followed by deposition of a passivation layer or interface layer using non-oxidative processes, such as hydrogen or nitrogen oxide
Implementation Method 4
Interface mobility can be enhanced by anneals in nitrogen atmosphere (e.g. nitric oxide)
Data Source
AI summary
Herein, a method of forming a semiconductor device may comprise forming a semiconductor substrate comprising silicon carbide at a surface thereof, cleaning a surface area of the semiconductor substrate by removing oxide species, carbon clusters, or other contaminants, and forming a dielectric layer above the cleaned surface of the semiconductor substrate. The method further provides a surface passivation at the interface of the cleaned surface of the semiconductor substrate and the dielectric layer.