Indium Semiconductor Plasma Etching for Smooth Low-Roughness Surfaces
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Solution Overview
Problem
Indium-containing compound semiconductor etching processes face challenges in achieving smooth surfaces and reducing surface roughness due to residual passivation, which affects the performance of optical devices and increases fabrication complexity.
Innovation Solution
A method involving a primary plasma etching process with a Halogen-containing and Nitrogen-containing gas mixture followed by a secondary plasma etching process with an Oxygen-containing component, applying RF bias power between 10 W and 50 W, to remove passivation material and excess surface material, thereby smoothing the substrate surfaces without requiring complex configuration or separate polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If excessive passivation is applied during etching to protect sidewalls, then sidewall protection is improved, but subsequent fabrication complexity increases due to difficulty in removing unwanted material
Solution Approach 1:
The secondary plasma process selectively extracts and removes the residual passivation material from the base and sidewalls after the primary etching process. This extraction step simplifies the overall fabrication process by eliminating the need for additional complex removal steps that would otherwise be required.
Solution Approach 2:
The secondary plasma process acts as an intermediary step between the primary etching and subsequent fabrication processes. It mediates by removing the problematic residual passivation, creating a clean surface that is ready for the next fabrication step without requiring complex additional processing.
2Manufacturing precision
If a cyclic etching process is used to remove passivation and smooth surfaces, then surface roughness is reduced, but process complexity increases due to precise process tuning requirements
Solution Approach 1:
The invention uses distinct parameter sets for the two plasma processes: the primary process uses parameters optimized for anisotropic etching with passivation, while the secondary process uses parameters optimized for passivation removal and surface smoothing. These parameter changes are straightforward and do not require complex cyclic tuning.
Solution Approach 2:
By segmenting the process into two simple sequential steps rather than one complex cyclic process, the invention achieves surface smoothing without requiring precise process tuning and configuration. Each step has clear, distinct parameters that are easier to control and reproduce.
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 achieves smooth and uniform surfaces with minimal residual passivation and surface roughness, simplifying the etching process and reducing the need for additional mechanical processing steps, while maintaining flexibility in vacuum conditions.
Implementation Method 1
performing a primary plasma etching process by generating a plasma from a first etchant gas mixture within the chamber to plasma etch the Indium-containing compound semiconductor material
Implementation Method 2
passivation material is formed from InN x compounds formed by reaction between the Indium-containing substrate and the Nitrogen-containing component in the primary plasma etching process
Implementation Method 3
performing a secondary plasma etching process by generating a plasma from a second etchant gas or gas mixture comprising an Oxygen-containing component
Implementation Method 4
the Oxygen-containing plasma of the secondary plasma etching process not only reacts with and removes the passivation material on the sidewalls and base of the etched feature, but also reacts with the Indium-containing surface material resulting in material removal and producing InO x
Implementation Method 5
an RF bias power is applied to the etched substrate during the secondary etching process and the RF bias power is between about 10 W and about 50 W
Data Source
Figure 1~2(b)
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AI summary
A method of plasma etching an Indium-containing compound semiconductor substrate and plasma etch apparatus for plasma etching an Indium-containing semiconductor substrate are provided.