GaN Plasma Etching With Sidewall Passivation for Rounded Trenches
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Solution Overview
Problem
Current dry etching methods for GaN trenches produce sharp corners that lead to charge leakage and limit the breakdown voltage of GaN transistors, while wet etching processes are time-consuming and environmentally unfriendly, and difficult to integrate into existing manufacturing flows.
Innovation Solution
A two-step plasma etching process using chlorine-based etchants with a fluorocarbon-based passivation material precursor to deposit passivation material on the trench walls, controlling the etch profile to achieve rounded corners without additional wet etch steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dry etching is used to etch GaN trenches, then the etching speed is fast and the process is environmentally friendly, but sharp corners are formed at the trench base leading to charge leakage
Solution Approach 1:
The patent changes the chemical parameters of the etching process by introducing a fluorocarbon-based passivation material precursor into the plasma etching recipe. This modifies the etching chemistry to deposit passivation material on the trench walls during etching, which rounds the corners at the trench base and reduces charge leakage while maintaining fast etching speed
Solution Approach 2:
The fluorocarbon-based passivation material acts as an intermediary substance that is deposited on the trench walls during the etching process. This intermediate layer modifies the etching behavior at the trench corners, rounding them off and preventing charge accumulation, thereby resolving the contradiction between fast etching and charge leakage
2Reliability
If wet etching is used to round the trench corners, then charge leakage is reduced, but the process time increases significantly and environmental hazards arise
Solution Approach 1:
The patent merges the etching and corner rounding operations into a single integrated plasma etching process. By incorporating the fluorocarbon-based passivation material precursor into the plasma recipe, the corner rounding function is combined with the main etching step, eliminating the need for separate wet etching steps and significantly reducing total process time
Solution Approach 2:
The patent replaces the wet chemical etching mechanism with a plasma-based mechanism. The fluorocarbon-based passivation material in the plasma process achieves corner rounding through plasma deposition and selective etching, substituting the wet chemical process with a dry plasma process that is faster and environmentally friendly
3Reliability
If wet etching is used to round trench corners, then charge leakage is minimized, but the process becomes difficult to integrate into existing manufacturing flows
Solution Approach 1:
The patent combines the corner rounding function with the existing plasma etching process by modifying the plasma recipe to include a fluorocarbon-based passivation material precursor. This integration allows corner rounding to be achieved within the existing plasma etching equipment and process flow, eliminating the need for separate wet etching steps and simplifying manufacturing integration
Solution Approach 2:
The modified plasma etching process achieves multiple functions simultaneously: it etches the GaN trench to the required depth and shape, deposits passivation material on the trench walls, and rounds the trench corners. This multi-functional approach eliminates the need for separate process steps and makes the process easily integrable into existing manufacturing flows
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 process produces GaN trenches with rounded corners, reducing charge leakage and increasing breakdown voltage, while being compatible with existing manufacturing processes and avoiding environmental hazards.
Implementation Method 1
performing a first plasma etch step to anisotropically etch the at least one GaN or GaN alloy layer through the opening
Implementation Method 2
the first plasma etch step uses an etch recipe comprising a chlorine-based etchant
Implementation Method 3
the second plasma etch step uses an etch recipe comprising a chlorine-based etchant and a fluorocarbon-based passivation material precursor and wherein the deposition of the passivation material within the feature
Implementation Method 4
performing a second plasma etch step to anisotropically etch the bottom surface of the partially formed feature through the opening while depositing a passivation material onto the walls
Data Source
AI summary
Plasma etching a substrate including at least one GaN or GaN alloy layer to form a feature. The plasma etching providing a substrate with a mask formed thereon, performing a first plasma etch step to anisotropically etch the at least one GaN or GaN alloy layer through the opening to produce a partially formed feature having one or more side walls and a bottom surface having a peripheral region, and performing a second plasma etch step to anisotropically etch the bottom surface of the partially formed feature through the opening while depositing a passivation material onto the walls.