Silicon Oxide Dry Etching with Low-Temperature Sublimable Residues
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Solution Overview
Problem
Existing methods for dry-etching silicon oxide without plasma face challenges such as insufficient etching speed, residue formation, and heat damage to non-target parts, particularly when using ammonia-based techniques, which require high temperatures and reduce productivity.
Innovation Solution
The method involves reacting silicon oxide with hydrogen fluoride and an organic amine compound in a non-plasma state, forming a sublimable reaction product that can be removed at low temperatures, using a gaseous hydrogen fluoride and organic amine compound mixture, or their salts, to achieve efficient etching without plasma-induced damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If ammonia gas is used for dry-etching silicon oxide, then etching speed is improved, but residue remains on the surface and high temperature heating is required
Solution Approach 1:
The patent changes the chemical parameters by replacing ammonia gas with organic amine compounds (such as trimethylamine, diethylamine, or dipropylamine). This substitution fundamentally alters the reaction product properties, enabling complete sublimation without residue while maintaining high etching speed at lower temperatures (100-200°C).
Solution Approach 2:
The reaction products using organic amines are designed to be volatile and easily removable, essentially 'disposable' intermediates that sublime completely. This contrasts with ammonia-based methods where the AFS layer residue persists and requires additional high-temperature removal steps.
2Object-generated harmful factors
If high temperature heating is applied to remove AFS layer, then residue is eliminated, but heat damage occurs to non-target parts
Solution Approach 1:
The patent changes the thermal parameters by using organic amine compounds that enable complete residue removal at low temperatures (100-200°C). This eliminates the need for high-temperature heating (>200°C) that causes heat damage to temperature-sensitive device components.
Solution Approach 2:
The patent converts the potential harm of residue formation into a benefit by selecting organic amines whose reaction products have high volatility and low sublimation temperatures. The residue problem is transformed into an advantage where the reaction product itself becomes easily removable through sublimation at safe temperatures.
3Object-generated harmful factors
If two-step etching process is used, then complete AFS layer removal is achieved, but productivity is reduced due to repeated heating and cooling
Solution Approach 1:
The patent merges the etching and residue removal functions into a single integrated process step. By using organic amine compounds, the reaction products sublime completely during or immediately after the etching step itself, eliminating the need for a separate high-temperature heating step and associated heating/cooling cycles.
Solution Approach 2:
The patent maintains continuous useful action by ensuring the etching reaction produces volatile products that are automatically removed through sublimation without interrupting the process flow. This continuous action eliminates the downtime required for heating and cooling cycles in two-step processes.
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 enables fast and residue-free etching of silicon oxide at temperatures of 200° C. or lower, improving productivity by eliminating the need for high-temperature treatments and reducing damage to non-target parts.
Implementation Method 1
the reaction product sublimates at a much lower temperature than ammonium fluorosilicate and can be removed at a low temperature
Implementation Method 2
the silicon oxide film chemically reacts with the gas mixture into ammonium fluorosilicate (AFS), thereby forming an AFS layer as a reaction product
Data Source
AI summary
The method of dry-etching silicon oxide of the present disclosure includes reacting silicon oxide with any one of the following (A) to (C): (A) a gaseous hydrogen fluoride and a gaseous organic amine compound, (B) a gaseous hydrogen fluoride salt of an organic amine compound, and (C) a gaseous hydrogen fluoride, a gaseous organic amine compound, and a gaseous hydrogen fluoride salt of an organic amine compound in a non-plasma state.