GaN PEC Etching via Cathode Pad and UV Light
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Solution Overview
Problem
Photoelectrochemical (PEC) etching of group III nitrides, such as gallium nitride (GaN), faces challenges in achieving effective etching rates due to limitations in the area of the cathode region and the use of semi-insulating substrates with non-conductive masks, which hinder the advancement of PEC etching processes.
Innovation Solution
A structure manufacturing method involving a conductive member, such as a cathode pad, in contact with the etching target, and a non-conductive mask to define the region to be etched, with the cathode pad not constituting the edge of the etched region, immersed in an alkaline or acidic etching solution containing peroxodisulfate ions and irradiated with UV light to enhance the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PEC etching is performed on group III nitrides using conventional methods, then the etching process can be carried out with simple apparatus, but the etching rate is insufficient due to limitations in cathode region area
Solution Approach 1:
The patent segments the cathode function by introducing a separate conductive member (cathode pad) that is electrically connected to the etching target but spatially separated from the mask edge. This allows the cathode area to be independently enlarged without affecting the mask definition, thereby increasing the etching rate while maintaining etching precision.
Solution Approach 2:
The patent transitions from a two-dimensional constraint where the mask edge defines both the etching boundary and the cathode edge, to a three-dimensional configuration where the conductive member extends beneath the mask. This dimensional change allows the cathode area to be increased in the vertical dimension while the mask maintains precise lateral definition.
2Manufacturing precision
If semi-insulating substrates with non-conductive masks are used, then the mask can provide good pattern definition, but PEC etching cannot be effectively performed due to lack of electrical connection
Solution Approach 1:
The patent introduces a conductive member as an intermediary element that bridges the electrical connection between the etching target and the etching solution. This conductive member acts as a mediator that enables PEC etching on semi-insulating substrates without compromising the pattern definition provided by the non-conductive mask.
Solution Approach 2:
The patent extracts the electrical connection function from the mask structure itself and places it in a separate conductive member. This separation allows the mask to maintain its non-conductive, high-precision pattern definition role while the conductive member independently provides the necessary electrical connection for PEC etching.
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 improves the etching rate by increasing the effective cathode area, facilitating PEC etching even with semi-insulating substrates and non-conductive masks, thereby advancing the etching process effectively.
Implementation Method 1
Photoelectrochemical (PEC) etching has been proposed as an etching technique for forming various structures on group III nitrides such as GaN
Implementation Method 2
etching the group III nitride that constitutes the region to be etched by immersing the treatment object in an alkaline or acidic etching solution containing peroxodisulfate ions as an oxidizing agent that accepts electrons
Implementation Method 3
irradiating the surface to be etched with light through the etching solution
Data Source
AI summary
A structure manufacturing method including: preparing a treatment object that includes an etching target having a surface to be etched comprising a conductive group III nitride and a region to be etched, a conductive member in contact with at least a portion of a surface of a conductive region of the etching target that is electrically connected to the region to be etched, and a mask formed on the surface to be etched and comprising a non-conductive material; and etching the group III nitride by immersing the treatment object in an alkaline or acidic etching solution containing peroxodisulfate ions as an oxidizing agent that accepts electrons, and irradiating the surface to be etched with light through the etching solution, wherein an edge that defines the region to be etched is constituted by an edge of the mask without including an edge of the conductive member.