Large-Diameter Nitride Substrate Growth for Uniform Crystal Quality
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Solution Overview
Problem
Large-diameter Group-III element nitride semiconductor substrates exhibit variations in quality due to regions with different crystal plane directions and impurity concentrations, leading to inconsistent device characteristics.
Innovation Solution
A method for producing a Group-III element nitride semiconductor substrate with a diameter of 100 mm or more, featuring a coefficient of variation in yellow luminescence intensity of 0.3 or less, achieved through controlled crystal growth using a Na flux method with an alumina crucible coated with aluminum nitride, ensuring uniform impurity distribution and reduced warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the substrate diameter is increased to 100 mm or more, then the productivity and device power handling capability are improved, but variations in quality and impurity concentration become more significant
Solution Approach 1:
The patent applies parameter changes by controlling the rotation speed of the crucible during crystal growth (specifically 30 rpm or higher) and adjusting the temperature gradient in the growth chamber. These parameter changes ensure uniform impurity distribution and prevent facet growth across the entire 100 mm or larger substrate diameter, thereby maintaining quality uniformity while enabling high-power device applications
2Device complexity
If the crystal growth area is expanded to reduce tiling joints, then the manufacturing complexity is reduced, but regions with different crystal plane directions and impurity concentrations are generated
Solution Approach 1:
The patent applies preliminary action by pre-coating the crucible inner surface with aluminum nitride before crystal growth. This preliminary coating prevents impurity incorporation at the crystal-substrate interface and ensures uniform nucleation across the entire growth area, eliminating the need for tiling while maintaining crystal plane uniformity throughout the large-diameter substrate
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 results in a substrate with suppressed variations in quality and reduced warping, enabling consistent device performance across the entire surface, suitable for high-frequency/high-power electronic devices.
Implementation Method 1
an alumina crucible coated with aluminum nitride
Implementation Method 2
controlled crystal growth using a Na flux method
Implementation Method 3
coefficient of variation of a yellow luminescence intensity in a range corresponding to 88% or more of an entire region of the first surface of 0.3 or less based on a photoluminescence spectrum obtained through photoluminescence measurement
Data Source
AI summary
There is provided a large-diameter Group-III element nitride semiconductor substrate including a first surface and a second surface, in which, despite its large diameter, variations in quality in the first surface are suppressed. A Group-III element nitride semiconductor includes: a first surface; and a second surface, wherein the Group-III element nitride semiconductor substrate has a diameter of 100 mm or more, and wherein the Group-III element nitride semiconductor substrate has a coefficient of variation of a yellow luminescence intensity in a range corresponding to 88% or more of an entire region of the first surface of 0.3 or less based on a photoluminescence spectrum obtained through photoluminescence measurement of a range of the entire region of the first surface.