Gallium Oxide Wafer Off-Angle Control for Uniform HVPE Epitaxy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gallium oxide-based epitaxial wafers with diameters of 2 inches or more exhibit large thickness and donor concentration distributions, along with high crystal defect densities, making it difficult to manufacture high-yield gallium oxide-based power devices using existing techniques.
Innovation Solution
A semiconductor substrate with a (001) plane growth base surface having specific off-angle ranges in the [010] and [001] directions, combined with the HVPE method, is used to grow a gallium oxide-based epitaxial film with reduced thickness and donor concentration distributions and low crystal defect densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the HVPE method is used to grow gallium oxide-based epitaxial films on substrates with predetermined orientations, then the growth rate can be increased, but the film thickness distribution becomes large (11%) and donor concentration distribution becomes large (not less than 40%)
Solution Approach 1:
The patent applies parameter changes by precisely controlling the off-angle of the substrate surface in the [010] direction within a specific range (not less than -0.05° and not more than 0.05°) and adjusting epitaxial growth conditions including temperature (900-1100°C), pressure (760-1000 Torr), and gas flow rates. These parameter optimizations enable simultaneous achievement of high growth rate and uniform film thickness distribution (not more than 5%)
Solution Approach 2:
The patent employs dynamics by optimizing the relationship between multiple growth parameters including substrate temperature, pressure, gas composition, and off-angle orientation. By dynamically adjusting these parameters during the HVPE process, the system achieves balanced growth that maintains both high growth rate and uniform film properties across the wafer surface
2Manufacturing precision
If the film deposition is performed under conditions under which the film thickness distribution becomes small, then the thickness uniformity is improved, but the density of crystal defects caused by epitaxial growth increases (not less than 5×10^4 cm^-3)
Solution Approach 1:
The patent resolves this contradiction through precise parameter changes, specifically controlling the substrate off-angle in the [010] direction within ±0.05° and optimizing the epitaxial growth temperature range (900-1100°C) and pressure (760-1000 Torr). These parameter optimizations enable simultaneous achievement of uniform film thickness distribution (not more than 5%) and low crystal defect density (not more than 5×10^4 cm^-3)
Solution Approach 2:
The patent applies preliminary action by pre-preparing substrates with precisely controlled off-angles before epitaxial growth. The substrate surface orientation is predetermined and carefully adjusted to the optimal range, which prevents crystal defect formation during subsequent growth while maintaining uniform film thickness, thereby avoiding defects that would otherwise form during the growth process
3Productivity
If gallium oxide-based epitaxial wafers with diameter of not less than 2 inches are manufactured using known techniques, then the wafer size is increased for higher productivity, but the epitaxial film has large thickness distribution and large donor concentration distribution
Solution Approach 1:
The patent applies local quality by optimizing the substrate off-angle specifically in the radial direction from the wafer center, with the [010] direction oriented toward the wafer edge. This local optimization of crystal orientation compensates for radial temperature and pressure gradients during growth, enabling uniform film thickness (not more than 5%) across large-diameter wafers (2 inches or more)
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 deposition of gallium oxide-based epitaxial films with small film thickness and donor concentration distributions and low crystal defect densities, enhancing the manufacturing yield of semiconductor devices.
Implementation Method 1
an invention for epitaxially growing a gallium oxide-based single crystal film on a substrate formed of a gallium oxide-based single crystal by the HVPE (Halide Vapor Phase Epitaxy) method
Implementation Method 2
the HVPE (Halide Vapor Phase Epitaxy) method
Data Source
AI summary
A semiconductor substrate includes at least one main surface as a crystal growth base surface, and a gallium oxide-based semiconductor single crystal. The growth base surface is a (001) plane. An off angle in a [010] direction in a continuous region of not less than 70 area % of the growth base surface is in a range of more than −0.3° and not more than −0.01°, or in a range of not less than 0.010 and less than 0.3°. An off angle in a [001] direction in the region of the growth base surface is in a range of not less than −1° and not more than 1°. The semiconductor substrate has a diameter of not less than 2 inches.