Silicon Oxide Dry Etching With Low-Temperature Sublimable Byproducts
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Solution Overview
Problem
Existing methods for dry-etching silicon oxide without plasma suffer from insufficient etching speed and residue generation, especially at low temperatures, and require high-temperature treatments that can cause heat damage to non-target parts.
Innovation Solution
A dry-etching method using a gaseous hydrogen fluoride and an organic amine compound in a non-plasma state, which reacts with silicon oxide to form a sublimable reaction product that can be removed at low temperatures, avoiding residue formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional dry-etching methods without plasma are used, then plasma damage is avoided, but etching speed is insufficient
Solution Approach 1:
The invention changes the chemical parameters of the etching system by introducing a two-step process: first forming an AFS layer through chemical reaction between HF/NH3 gases and silicon oxide, then removing it through thermal decomposition at elevated temperatures. This parameter change enables both plasma-free operation and improved etching speed
Solution Approach 2:
The invention implements continuous useful action by maintaining gas flow during the AFS layer formation and then performing thermal decomposition in the same chamber without breaking vacuum, eliminating idle time between steps and maintaining continuous productive action
2Productivity
If COR treatment alone is performed to remove silicon oxide, then etching is achieved, but AFS layer remains as residue on the surface
Solution Approach 1:
The invention segments the etching process into two distinct steps: COR (chemical oxide removal) to form the AFS layer, and PHT (post heat treatment) to decompose and remove the AFS layer. This segmentation ensures complete surface cleaning while maintaining etching efficiency
Solution Approach 2:
The AFS layer acts as an intermediary substance that temporarily holds the etched material, allowing controlled removal through thermal decomposition. This intermediary approach prevents direct plasma-surface interaction while ensuring complete residue removal
3Manufacturing precision
If PHT treatment is conducted at higher temperature than COR treatment to remove thick AFS layer, then complete residue removal is achieved, but heat damage occurs to parts other than silicon oxide film
Solution Approach 1:
The invention uses periodic action by alternating between COR step (forming AFS layer) and PHT step (removing AFS layer) in cycles, allowing controlled thermal exposure that removes residues while limiting cumulative heat damage through repeated short-duration heating cycles
4Manufacturing precision
If chamber is heated or cooled every time steps are switched between COR and PHT, then complete etching process is achieved, but productivity is reduced
Solution Approach 1:
The invention merges the COR and PHT steps into a single continuous process within the same vacuum chamber, eliminating the need for chamber heating/cooling cycles between steps. The chamber maintains stable temperature while the substrate undergoes sequential treatment, significantly improving productivity
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 efficient etching of silicon oxide at a sufficient speed without generating residues, even at temperatures of 200° C. or lower, thereby improving productivity and reducing heat damage to non-target parts.
Implementation Method 1
reacting silicon oxide with a gaseous hydrogen fluoride and a gaseous organic amine compound
Implementation Method 2
the reaction product sublimates at a much lower temperature than ammonium fluorosilicate and can be removed at a low temperature
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.