Indium Semiconductor Plasma Etching for Smooth Sidewalls
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Solution Overview
Problem
Existing plasma etching methods for indium-containing compound semiconductors face challenges in achieving smooth and uniform sidewalls and bases while avoiding passivation residue, leading to surface roughness and performance degradation in optical devices.
Innovation Solution
A two-step plasma etching process using a halogen-containing and nitrogen-containing primary etch followed by an oxygen-containing secondary etch, with controlled RF bias power, effectively removes passivation and excess material, resulting in smooth surfaces without complex process tuning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If passivation gas (CH4, O2 or N2) is used during plasma etching to achieve anisotropic etching, then etch anisotropy is improved, but surface roughness increases and device performance degrades
Solution Approach 1:
The etching process is divided into two distinct stages: a first plasma etching process using halogen-containing gas for anisotropic etching, followed by a second plasma etching process using oxygen-containing gas for surface smoothing. This segmentation allows each process to optimize for its specific function without compromise
Solution Approach 2:
The invention changes the chemical composition parameter of the etchant gas between two sequential processes. The first process uses halogen-containing gas (Cl2, HBr) for anisotropic etching, while the second process uses oxygen-containing gas (O2, CO, CO2, N2O) to remove passivation and smooth surfaces, eliminating the need for passivation gases like CH4
2Object-affected harmful factors
If cyclic etching process is used to remove passivation and smooth surfaces, then surface roughness is reduced, but process complexity increases
Solution Approach 1:
The invention implements a continuous two-step plasma etching process where the first plasma etching process performs anisotropic etching and the second plasma etching process continuously removes passivation and smooths surfaces. This continuous action eliminates the need for complex cyclic tuning while maintaining surface quality
Solution Approach 2:
The process uses a simple parameter change - switching from halogen-containing gas to oxygen-containing gas between two sequential etching steps. This straightforward parameter transition avoids the complex process tuning and configuration required by cyclic etching methods
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 produces indium-containing compound semiconductor features with minimal surface roughness and uniformity, enhancing device performance and simplifying the fabrication process.
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
Ion bombardment at the bottom of the feature removes the passivation at the base of the feature while the passivation on the sidewall inhibits lateral etching
Implementation Method 3
The etchant gas mixtures used in these processes are typically based on Cl2 and/or HBr
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 InOx
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
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 can use a primary plasma etching process and a secondary plasma etching process. The primary plasma etching process uses a halogen-containing component and a nitrogen-containing component. The secondary plasma etching process uses an oxygen-containing component.