GaN Substrate Storage in Low-Oxygen Atmosphere
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Solution Overview
Problem
Conventional methods for storing GaN substrates under clean air conditions lead to oxidation, prohibiting the manufacture of semiconductor devices with favorable properties.
Innovation Solution
Storing GaN substrates in an atmosphere with oxygen concentration not greater than 15 vol.% and water-vapor concentration not greater than 20 g/m³, with specific orientation and roughness conditions to minimize oxidation and maintain high photoemission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If GaN substrates are stored under clean air atmosphere, then storage is simple and convenient, but the substrate surface oxidizes and device properties deteriorate
Solution Approach 1:
The patent applies inert atmosphere storage by controlling the storage environment to have oxygen concentration of 10 vol.% or less and water vapor concentration of 15 g/m³ or less. This creates a low-oxygen, low-moisture environment that prevents oxidation of the GaN substrate surface while maintaining practical storage conditions, thus resolving the contradiction between storage convenience and device property preservation.
Solution Approach 2:
The patent changes the storage environment parameters (oxygen concentration and water vapor concentration) from conventional clean air conditions to controlled low-oxygen, low-moisture conditions. By adjusting these physical-chemical parameters of the storage atmosphere, the patent prevents surface oxidation while maintaining storage feasibility, thereby resolving the technical contradiction.
2Productivity
If GaN substrates are stored for prolonged periods, then manufacturing flexibility is improved, but surface oxidation occurs and photoemission efficiency decreases
Solution Approach 1:
The patent implements prolonged storage capability by maintaining substrates in an inert-like atmosphere with controlled oxygen (≤10 vol.%) and water vapor (≤15 g/m³) concentrations. This environment prevents oxidation during extended storage periods, enabling manufacturing flexibility without compromising photoemission efficiency, thus resolving the contradiction between productivity and reliability.
Solution Approach 2:
The patent applies preliminary protection by establishing controlled storage conditions before oxidation can occur. By pre-controlling the atmosphere parameters (oxygen and water vapor concentrations) in the storage environment, the patent prevents surface degradation during prolonged storage, thereby maintaining photoemission efficiency while enabling manufacturing flexibility.
3Reliability
If GaN substrates with off-axis orientation are used, then blue-shift is reduced and emission efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent changes the crystallographic orientation parameter by specifying off-axis orientations (e.g., m-plane, a-plane, or semi-polar orientations) instead of conventional c-axis orientation. This parameter change in substrate orientation reduces blue-shift and improves emission efficiency, while the patent manages the associated manufacturing precision requirements through controlled growth and processing methods.
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 allows for the production of semiconductor devices with reduced blue-shift and high emission efficiency by controlling oxygen and water-vapor interaction with the substrate surfaces.
Implementation Method 1
the surface of the GaN substrates oxidizes due to the prolonged storage
Data Source
AI summary
A GaN substrate is stored within an atmosphere in which the oxygen concentration is not greater than 15 vol. % and the water-vapor concentration is not greater than 20 g/m3. The GaN substrate (1) has a planar first principal face (1m), and in an arbitrary point (P) along the first principal face (1m) and separated 3 mm or more from the outer edge thereof, the GaN substrate's plane orientation has an off-inclination angle Δα of −10° or more, 10° or less with respect to the plane orientation of an arbitrarily designated crystalline plane (1a) that is inclined 50° or more, 90° or less with respect to a plane (1c), being either the (0001) plane or the (000 1) plane, through the arbitrary point. This enables storing GaN substrates whose principal-face plane orientation is other than (0001) or (000 1), making available GaN substrates with which semiconductor devices of favorable properties can be manufactured.