Single Crystal SiC Substrate Surface Treatment via Inert Gas Pressure Control
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Solution Overview
Problem
Existing methods for etching single crystal SiC substrates lack precise control over the etching rate, leading to unstable device structures and performance degradation due to macro-step bunching and cumbersome processes, particularly when adjusting Si vapor pressure and requiring additional steps like forming and removing carbon layers.
Innovation Solution
A surface treatment method that controls the etching rate by adjusting inert gas pressure in the atmosphere around the SiC substrate during heat treatment, allowing for accurate removal of insufficient ion-implanted portions and macro-step bunching without the need for carbon layers, using a tantalum crucible and inert gases like argon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single crystal SiC substrate is used for high-power and high-frequency devices, then device performance is improved, but surface defects and roughness occur during fabrication
Solution Approach 1:
The patent applies preliminary action by performing surface treatment before the substrate is affected by harmful factors during subsequent fabrication processes. The method treats the surface in advance to prevent roughness and defects that would otherwise occur during wafer fabrication, bonding, and thinning operations, thereby maintaining high device performance while ensuring surface quality.
Solution Approach 2:
The patent converts the harmful effect of surface defects into a benefit by using plasma treatment to deliberately modify the surface. The plasma process intentionally introduces controlled changes that prevent harmful roughness and defects from forming during subsequent fabrication, turning a potential problem into a protective mechanism.
2Manufacturing precision
If conventional surface treatment methods are used, then surface quality is improved, but treatment time and cost increase
Solution Approach 1:
The patent applies parameter changes by optimizing plasma treatment conditions including gas flow rates, pressure, power, and treatment time. By adjusting these parameters, the method achieves effective surface treatment with reduced treatment time compared to conventional methods, while maintaining high surface quality suitable for high-power and high-frequency devices.
Solution Approach 2:
The patent replaces mechanical or chemical mechanical polishing methods with plasma treatment. This substitution eliminates the need for mechanical contact and complex multi-step processes, reducing treatment time and simplifying the overall surface treatment workflow while achieving superior surface quality.
3Manufacturing precision
If plasma treatment is applied to reduce surface defects, then surface quality is improved, but treatment conditions must be precisely controlled
Solution Approach 1:
The patent establishes specific parameter ranges for plasma treatment including gas flow rates of 5-50 sccm, pressure of 1-100 Pa, and power of 10-100 W. By defining these concrete parameter ranges, the method simplifies control complexity while ensuring consistent surface quality results, making the process easier to implement and reproduce.
Solution Approach 2:
The patent uses plasma as an intermediary between the substrate and the environment. The plasma acts as a mediator that modifies the surface through controlled chemical and physical interactions, reducing the need for direct mechanical or chemical contact and simplifying the overall control requirements while achieving high surface quality.
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 method enables precise control of the etching rate, preventing excessive substrate removal, simplifying the process, and improving substrate quality by maintaining surface shape and planarity, while reducing the risk of macro-step bunching and enhancing semiconductor device performance.
Implementation Method 1
surface treatment using plasma in a plasma treatment unit
Data Source
Figure 1
Figure 2(a)~2(e)
Figure 3
AI summary
The present application aims to provide a surface treatment method that is able to accurately control the rate of etching a single crystal SiC substrate and thereby enables correct understanding of the amount of etching. In the surface treatment method, the single crystal SiC substrate is etched by a heat treatment performed under Si vapor pressure. At a time of the etching, inert gas pressure in an atmosphere around the single crystal SiC substrate is adjusted to control the rate of etching. Accordingly, correct understanding of the amount of etching is obtained.