Nitride Semiconductor Surface Roughness via Selective Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In methods of manufacturing semiconductor devices, regrown nitride semiconductor layers often have a rough surface, which can lead to increased contact resistance and reduced device performance.
Innovation Solution
A method involving the formation of a first nitride semiconductor layer, followed by a first and second layer, with an opening exposing the first layer, and then forming a second nitride semiconductor layer of a specific conductivity type. The second layer is removed using an acidic solution, where the etching rate of the first layer is lower than the second layer, resulting in improved surface roughness and reduced contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nitride semiconductor layer is regrown to reduce contact resistance, then contact resistance decreases, but surface roughness increases
Solution Approach 1:
The patent divides the protective layer into two distinct layers: a first layer (e.g., silicon nitride) with low etching rate and a second layer (e.g., zinc oxide) with high etching rate. This segmentation allows each layer to serve a specific function - the first layer protects the nitride semiconductor layer during etching, while the second layer is easily removed to reveal a smooth surface, thereby resolving the contradiction between contact resistance reduction and surface roughness control
Solution Approach 2:
The patent applies different materials with different etching rates to different layers, creating local quality variations. The first layer has low etching rate to protect the underlying nitride semiconductor layer, while the second layer has high etching rate for easy removal. This local differentiation of material properties enables simultaneous achievement of low contact resistance and smooth surface finish
2Manufacturing precision
If a protective layer is formed during etching, then etching selectivity is improved, but process complexity increases
Solution Approach 1:
The patent utilizes parameter changes in etching rate between different materials to achieve selective removal. The second layer (zinc oxide) has a significantly higher etching rate than the first layer (silicon nitride), allowing the second layer to be removed while leaving the first layer intact. This parameter-based differentiation simplifies the process by using inherent material properties rather than complex process controls
Solution Approach 2:
The first layer acts as an intermediary protective layer between the nitride semiconductor layer and the etching environment. It provides the necessary protection during etching operations while being designed to remain after the second layer is removed, thus mediating between the need for protection and the need for surface smoothness
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 results in a semiconductor device with reduced surface roughness and lower contact resistance between the electrode and the nitride semiconductor layer, enhancing the performance of semiconductor devices like high-electron-mobility transistors.
Implementation Method 1
removing the second layer using an acidic solution; A first etching rate of the first layer for the acidic solution is lower than a second etching rate of the second layer for the acidic solution
Data Source
AI summary
A method of manufacturing a semiconductor device includes forming a first nitride semiconductor layer containing Ga on a substrate; forming a first layer on the first nitride semiconductor layer; forming a second layer on the first layer; forming an opening in which the first nitride semiconductor layer is exposed in the second layer and the first layer; forming a second nitride semiconductor layer of a first conductivity type on a surface, exposed in the opening, of the first nitride semiconductor layer; removing the second layer using an acidic solution; and after removing the second layer, forming an electrode on the second nitride semiconductor layer. A first etching rate of the first layer for the acidic solution is lower than a second etching rate of the second layer for the acidic solution.