SiC Epitaxial Wafer Growth with Continuous Gas Supply to Limit Step Bunching
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Solution Overview
Problem
Existing methods for producing epitaxial silicon carbide wafers struggle with reproducibility and stability in reducing step bunching, leading to variations in device quality and yield, as surface conditions degrade during the transition from etching to epitaxial growth.
Innovation Solution
Continuing to supply hydrogen carrier gas and silicon-based material gas during the stabilization of epitaxial growth conditions after etching treatment, ensuring a stable low surface energy for the SiC substrate, and introducing carbon-based material gases only after conditions stabilize, to promote stable epitaxial growth and reduce step bunching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional etching treatment is performed followed by epitaxial growth with interruption of silicon-based material gas, then the epitaxial growth process can be initiated, but step bunching occurs and surface conditions become unstable
Solution Approach 1:
The patent maintains continuous supply of silicon-based material gas from the etching treatment through the epitaxial growth initiation phase. This continuous action prevents surface condition degradation and maintains stable low surface energy on the SiC substrate, thereby suppressing step bunching while enabling smooth transition to epitaxial growth
Solution Approach 2:
The patent prepares the SiC substrate surface by performing etching treatment with silicon-based material gas present before initiating epitaxial growth. This preliminary action creates and maintains a stable surface condition with low surface energy, preventing step bunching from occurring during the transition phase
2Productivity
If silicon-based material gas is interrupted during the transition from etching to epitaxial growth, then the growth process can start, but surface conditions degrade and reproducibility decreases
Solution Approach 1:
The patent maintains continuous supply of silicon-based material gas throughout the transition period from etching to epitaxial growth. This continuous action prevents surface condition degradation by maintaining stable low surface energy on the SiC substrate, thereby ensuring reproducibility while enabling growth initiation
3Manufacturing precision
If hydrogen carrier gas and silicon-based material gas are continued to be supplied during stabilization, then surface energy remains stable and low, but the process complexity increases
Solution Approach 1:
The patent maintains continuous supply of hydrogen carrier gas and silicon-based material gas during the stabilization period. This continuous action keeps surface energy stable and low on the SiC substrate, preventing step bunching. The gas flow rates are carefully controlled to maintain the desired surface conditions without requiring complex additional equipment
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 enables the production of epitaxial SiC wafers with significantly reduced step bunching, improving the quality and reproducibility of the epitaxial films, allowing for the formation of high-quality electronic devices with enhanced characteristics and yield.
Implementation Method 1
an SiC substrate is set in an epitaxial growth furnace, the inside of the epitaxial growth furnace is evacuated, then a carrier gas of hydrogen is introduced and the pressure is adjusted to 2×10 3 Pa, a silicon-based material gas is introduced, and the SiC substrate is etched
Implementation Method 2
the SiC substrate is formed with an SiC thin film by epitaxial growth by the thermal CVD process (thermal chemical vapor deposition process)
Implementation Method 3
after the introduction of a carbon-based material gas is started, epitaxial growth is performed
Implementation Method 4
epitaxial growth by the thermal CVD process
Data Source
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AI summary
The object is to produce with good reproducibility an epitaxial silicon carbide wafer having a high quality silicon carbide single crystal thin film with little step bunching. To achieve this object, for etching the silicon carbide single crystal substrate in the epitaxial growth furnace, hydrogen carrier gas and silicon-based material gas are used. After the etching treatment is finished as well, the epitaxial growth conditions are changed in the state in the state supplying these gases. When the conditions stabilize, a carbon-based material gas is introduced for epitaxial growth.