GaN Substrate Manufacturing via Inner Liner Gas Isolation
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Solution Overview
Problem
The challenge lies in manufacturing large-size substrates without cracking or melt-back issues, particularly when using silicon substrates due to differences in thermal expansion coefficients with gallium nitride substrates, which lead to stress and damage during the substrate formation process.
Innovation Solution
An apparatus is designed with a deposition chamber, a susceptor, and an inner liner that isolates etch gas from deposition gas, allowing for the simultaneous or sequential deposition of a second substrate material layer on a first substrate while etching the first substrate, using a support unit to manage stress and prevent cracking by controlling the deposition and etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon substrates are used as growth substrates, then manufacturing cost is reduced and large-size substrates can be manufactured, but stress and damage occur due to difference in coefficient of thermal expansion between silicon and gallium nitride substrates
Solution Approach 1:
The apparatus divides the substrate processing into two distinct sections: a deposition section for forming the gallium nitride layer on the silicon substrate, and an etching section for removing the silicon substrate. This segmentation allows independent optimization of each process, enabling the use of silicon substrates for large-size, low-cost manufacturing while eliminating the stress and damage issues through complete substrate removal.
Solution Approach 2:
The invention extracts the problematic silicon substrate after the gallium nitride layer is formed. By using the etching section to remove the silicon substrate through the center hole, only the desired gallium nitride layer remains as a free-standing substrate, eliminating the source of stress and damage while preserving the benefits of using silicon for cost-effective large-size manufacturing.
2Manufacturing precision
If the first substrate is removed after formation of the second substrate, then a free-standing substrate is achieved, but the process time is extended
Solution Approach 1:
The invention merges the deposition and etching processes into a single integrated apparatus where both operations can occur simultaneously or in overlapping time periods. The deposition section forms the gallium nitride layer while the etching section removes the silicon substrate through the center hole, reducing total process time while maintaining free-standing substrate quality.
Solution Approach 2:
The etching process begins during the deposition process rather than waiting for deposition to complete. This continuous action approach allows the silicon substrate to be removed progressively as the gallium nitride layer forms, eliminating idle time and reducing overall process duration while ensuring the final free-standing substrate meets quality requirements.
3Device complexity
If etch gas and deposition gas are not isolated, then the apparatus structure is simplified, but the etch gas contaminates the deposition gas and affects substrate quality
Solution Approach 1:
The apparatus is segmented into a deposition section and an etching section with distinct gas environments. The inner liner creates separate zones where deposition gas and etch gas do not mix, preventing contamination while maintaining a manageable apparatus structure. This spatial segmentation allows both processes to occur simultaneously without compromising substrate quality.
Solution Approach 2:
The inner liner acts as an intermediary structure that physically separates the deposition and etching gas flows. It guides the etch gas through the center hole to the rear surface of the substrate while preventing etch gas from entering the deposition section, thus protecting substrate quality without requiring complete apparatus 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
This approach enables the production of large-size substrates without melt-back or cracking, ensuring a free-standing substrate with reduced stress and improved productivity by removing the first substrate during or after the formation of the second substrate material layer.
Implementation Method 1
a deposition section in which a deposition gas is supplied to deposit a second substrate material layer on a first substrate
Implementation Method 2
an etching section in which an etch gas is supplied to remove the first substrate by etching
Data Source
AI summary
An apparatus includes a deposition chamber housing that accommodates a growth substrate, a supply nozzle to supply a deposition gas for forming a target large-size substrate on the growth substrate into the deposition chamber housing, a susceptor to support the growth substrate and expose a rear surface of the growth substrate to an etch gas, and an inner liner connected to the susceptor. The inner liner is to isolate the etch gas from the deposition gas and guide the etch gas toward the rear surface of the growth substrate. The susceptor includes a center hole that exposes the rear surface of the growth substrate and a support protrusion supporting the growth substrate, the support protrusion protruding toward the center of the center hole from an inner sidewall of the susceptor defining the center hole.