β-Ga2O3 HVPE Gas Inlet Layout to Suppress Killer Defects
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Solution Overview
Problem
The HVPE method for growing β-Ga2O3-based single crystal films often results in a higher occurrence of killer defects, which significantly degrade device characteristics, and existing techniques lack methods to effectively reduce or prevent these defects.
Innovation Solution
A method for manufacturing a β-Ga2O3-based single crystal semiconductor film involves placing a semiconductor substrate in an HVPE apparatus with specific gas inlet configurations, ensuring that the oxygen-including gas reaches the growth base surface most easily and the Ga chloride gas reaches it least easily, thereby reducing the formation and deposition of Ga oxide grains, which are the primary cause of killer defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the HVPE method is used to grow β-Ga2O3-based single crystal films, then the crystal growth efficiency is improved, but the occurrence of killer defects increases
Solution Approach 1:
The patent applies local quality by creating different gas concentration zones at different locations above the substrate. The gas inlets are positioned at different heights to create a gradient where Ga chloride gas concentration is lower near the substrate surface while oxygen and dopant gases are more uniformly distributed. This localized control of gas composition prevents excessive Ga oxide formation at the growth front, thereby reducing killer defects while maintaining high growth efficiency.
Solution Approach 2:
The patent introduces a vertical dimension (height) for gas inlet positioning to control the gas composition distribution. By arranging gas inlets at different heights (first inlet at height h1, second inlet at height h2 where h1 > h2), the patent creates a three-dimensional gas flow pattern that controls the relative concentrations of Ga chloride, oxygen, and dopant gases reaching the substrate, thereby resolving the contradiction between growth efficiency and defect reduction.
2Speed
If Ga chloride gas flows easily to the growth base surface, then the growth rate is improved, but the formation of Ga oxide grains increases causing killer defects
Solution Approach 1:
The patent creates a localized gas environment where the concentration of Ga chloride gas near the substrate surface is controlled to be lower than that of oxygen and dopant gases. This is achieved by positioning the Ga chloride gas inlet at a greater height from the substrate, ensuring that Ga oxide grain formation is suppressed while maintaining adequate growth rate through balanced gas supply.
Solution Approach 2:
The patent changes the parameter of gas inlet height to control the relative flow rates and concentrations of different gases. By setting the first gas inlet (supplying Ga chloride) at height h1 greater than the second gas inlet (supplying oxygen and dopant) at height h2, the patent optimizes the gas composition parameters at the substrate surface to prevent harmful Ga oxide grain formation while maintaining growth rate.
3Device complexity
If the inlets for oxygen and dopant gases are positioned at the same height, then the device complexity is reduced, but the control precision over gas composition is insufficient leading to killer defects
Solution Approach 1:
The patent segments the gas supply system into two distinct levels: a first gas inlet for Ga chloride at height h1 and a second gas inlet for oxygen and dopant gases at height h2. This segmentation allows independent control of different gas compositions, enabling precise control over the gas environment at the substrate surface while maintaining relatively simple device structure.
Solution Approach 2:
The patent uses the vertical height dimension to differentiate gas inlet positions, creating a two-level gas supply structure. This dimensional approach allows precise control of gas composition without significantly increasing device complexity, as the height difference alone provides the necessary control mechanism for preventing killer defects.
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 method significantly reduces the in-plane density of killer defects in the semiconductor film to no more than 10 defects/cm2, leading to improved device characteristics and increased manufacturable element size, allowing for the production of semiconductor devices with excellent forward and reverse leakage current characteristics.
Implementation Method 1
epitaxially growing a semiconductor film comprising a β-Ga2O3-based single crystal on the growth base surface of the semiconductor substrate by flowing a Ga chloride gas, an oxygen-including gas and a dopant-including gas
Implementation Method 2
HVPE (Halide Vapor Phase Epitaxy) method
Implementation Method 3
it has been found that, in growing a β-Ga2O3-based single crystal film by the HVPE method, Ga oxide grains are likely to be formed in a vapor phase
Data Source
AI summary
A method for manufacturing a semiconductor film includes placing a semiconductor substrate including a β-Ga2O3-based single crystal in a reaction chamber of an HVPE apparatus. When the semiconductor substrate is placed so that the growth base surface faces upward, an inlet for a dopant-including gas into the space is positioned higher than an inlet for an oxygen-including gas into the space and an inlet for a Ga chloride gas into the space is positioned higher than the inlet for the dopant-including gas into the space. When the semiconductor substrate is placed so that the growth base surface faces downward, the inlet for the dopant-including gas into the space is positioned higher than the inlet for the Ga chloride gas into the space and the inlet for the oxygen-including gas into the space is positioned higher than the inlet for the dopant-including gas into the space.