Defect Removal via Oxidation and Etching on SiC Substrates
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Solution Overview
Problem
Surface defects on silicon-carbide and epitaxial wafers lead to increased surface roughness, which affects subsequent processes, causes defects in single crystal layer growth, and results in increased leakage current and reduced device reliability due to non-uniform metal electrode deposition and patterns.
Innovation Solution
An apparatus and method utilizing an atomic force microscope (AFM) to detect and oxidize defects, forming an oxide layer that can be easily removed, improving surface roughness and substrate quality, and including a humidity controlling system to optimize oxide layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to remove surface defects, then manufacturing complexity increases, but defect removal effectiveness remains insufficient
Solution Approach 1:
The defect removal process is segmented into three distinct stages: detection (using optical microscope or AFM), oxidation (forming oxide layer on defects), and removal (etching oxide layer). This segmentation allows each stage to be optimized independently, improving overall effectiveness while maintaining clear process control
Solution Approach 2:
An oxide layer is introduced as an intermediary substance that selectively forms on defect surfaces during oxidation. This intermediary layer serves as a marker for defect locations and provides a controlled removal mechanism through selective etching, enabling precise defect removal without affecting the surrounding substrate
2Reliability
If surface defects are not removed, then surface roughness increases, but device reliability decreases
Solution Approach 1:
The oxidation step is performed as a preliminary action before final defect removal. By oxidizing defects first, the method prepares them for selective removal in subsequent etching steps, ensuring that defects are eliminated before they can affect surface roughness or device performance
Solution Approach 2:
The method changes the chemical state of defects by oxidizing them, transforming the defect surface composition. This parameter change enables selective identification and removal of defects through subsequent etching processes, ultimately improving surface roughness while enhancing device reliability
3Productivity
If oxide layer formation is performed without humidity control, then oxidation efficiency decreases, but process complexity increases with humidity control
Solution Approach 1:
The humidity control system serves multiple functions: it optimizes oxidation efficiency by maintaining appropriate moisture levels, ensures uniform oxide layer formation across the substrate, and facilitates controlled etching of the oxide layer. This multi-functionality justifies the added process complexity
Solution Approach 2:
Humidity is controlled as a critical process parameter during oxidation to optimize the reaction conditions. By maintaining specific humidity levels, the oxidation efficiency is enhanced and oxide layer formation is improved, demonstrating that the parameter control yields proportional productivity gains
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 method effectively removes defects, enhancing substrate quality and device performance by improving surface roughness and reducing leakage current, thereby extending device lifespan and increasing reliability.
Implementation Method 1
The defect may be oxidized by using the AFM and the oxidized defect may be easily removed
Implementation Method 2
a humidity controlling part for controlling humidity in a chamber in which the substrate is placed
Implementation Method 3
an image processing part for observing a surface of a substrate
Implementation Method 4
forming an oxide layer by oxidizing the defect
Data Source
AI summary
An apparatus for removing a defect according to the embodiment includes an image processing part for observing a surface of a substrate; a layer forming part for forming a layer on the surface of the substrate; and a humidity controlling part for controlling humidity in a chamber in which the substrate is placed. A method for removing a defect according to the embodiment includes detecting the defect on a surface of a substrate; forming an oxide layer by oxidizing the defect; and removing the oxide layer. A method for removing a defect according to another embodiment includes forming an oxide layer on an entire surface of a substrate; and removing the oxide layer to remove the defect.