GaN Semiconductor Recess Etching via Bromine Microwave Plasma
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Solution Overview
Problem
The high electron temperature in inductively coupled plasma reactive-ion etching (ICP-RIE) leads to uneven etching surfaces and residual chlorine impurities in GaN-based semiconductor devices, degrading their electrical characteristics.
Innovation Solution
A manufacturing method involving a microwave plasma process using a bromine-based gas to form a recessed portion in the semiconductor layer, with a sacrificial layer to remove impurities and a wet etching process to create a smooth, low-halogen surface, and forming an electrode layer electrically connected to the semiconductor layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ICP-RIE using chlorine-based gas is used for etching, then etching capability is achieved, but residual chlorine impurities remain in the etched surface degrading electrical characteristics
Solution Approach 1:
The patent changes the etching gas parameter from chlorine-based gas to bromine-based gas in microwave plasma etching. This parameter change eliminates residual chlorine impurities while maintaining effective etching capability, thereby improving electrical characteristics of the GaN-based semiconductor device.
Solution Approach 2:
The patent substitutes the ICP-RIE process with microwave plasma etching process. This substitution changes the plasma generation mechanism and allows for better control of ion energy and temperature, reducing damage to the semiconductor surface and eliminating residual chlorine impurities.
2Productivity
If ICP-RIE is used for etching, then etching is performed, but high-energy ions collide with semiconductor causing uneven surface and damage
Solution Approach 1:
The patent changes the plasma generation method from inductive coupling to microwave heating, and uses bromine-based gas instead of chlorine-based gas. These parameter changes result in lower ion energy and temperature during etching, preventing high-energy ion damage and producing a more uniform etching surface.
3Productivity
If chlorine-based gas is used for etching, then etching is achieved, but chlorides form in surface acting as impurities
Solution Approach 1:
The patent changes the etching gas from chlorine-based (Cl2, BCl3) to bromine-based gas. This parameter change fundamentally alters the chemical composition of the etching process, eliminating chlorine impurities from the etched surface while maintaining effective etching rate through bromine-based chemistry.
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 GaN-based semiconductor device with improved surface smoothness and reduced halogen impurities, enhancing electron field-effect mobility and electrical characteristics.
Implementation Method 1
forming a recessed portion by etching a portion of the first semiconductor layer through a microwave plasma process, using a bromine-based gas
Implementation Method 2
forming a first sacrificial layer that contacts the first semiconductor layer and has a higher solid solubility for impurities included in the first semiconductor layer than the first semiconductor layer; annealing the first sacrificial layer and the first semiconductor layer
Implementation Method 3
removing the first sacrificial layer through a wet process
Data Source
AI summary
Provided is a method of manufacturing a gallium-nitride-based semiconductor device, comprising forming a first semiconductor layer of a gallium-nitride-based semiconductor; and forming a recessed portion by dry etching a portion of the first semiconductor layer via a microwave plasma process using a bromine-based gas.