Cyclic Silicon Oxide-Nitride Etch Without Polymeric Passivation
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Solution Overview
Problem
Conventional etch processes for semiconductor manufacturing face challenges in selectively etching silicon nitride and silicon oxide materials, particularly in 3D NAND structures, where passivation materials can lead to non-uniform profiles and arcing issues due to the formation of polymeric passivation on sidewalls and wafer bevels.
Innovation Solution
A cyclic etch process involving exposure to a fluorine-containing precursor and a hydrogen-containing precursor, followed by an inert precursor, is used to form and remove fluorinated layers at low temperatures, enhancing directionality without the need for polymeric passivation, thereby reducing profile issues and arcing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymeric passivation is used to protect sidewalls during etching, then etch selectivity is improved, but profile uniformity deteriorates and arcing issues occur
Solution Approach 1:
The patent removes polymeric passivation materials from the etch process entirely, replacing them with in-situ formed fluorinated passivation layers that are automatically removed after etching. This extraction of harmful polymeric materials eliminates the source of profile non-uniformity and arcing while maintaining etch selectivity through controlled fluorine chemistry
Solution Approach 2:
The patent changes the chemical parameters by using fluorine-containing precursors (NF3, CF4) at controlled temperatures (20-40°C) to form volatile fluorinated passivation layers instead of polymeric materials. This parameter change transforms the passivation mechanism from polymeric deposition to controlled fluorination, achieving both selectivity and uniformity
2Length of moving object
If conventional dry etching is used to penetrate constrained trenches, then etch penetration is improved, but substrate damage increases due to electric arcs
Solution Approach 1:
The patent uses fluorine-containing gases (NF3, CF4) in a controlled inert atmosphere to perform etching. These gases provide chemically reactive fluorine species for etching while maintaining an overall inert environment that prevents unwanted side reactions and reduces plasma instability, thereby minimizing substrate damage from electric arcs
Solution Approach 2:
The patent employs composite gas chemistry combining fluorine-containing precursors with hydrogen-containing precursors. This composite approach creates a synergistic effect where fluorine provides etch capability and hydrogen helps terminate dangling bonds and stabilize the plasma, reducing substrate damage while maintaining trench penetration
3Object-affected harmful factors
If low temperature etching is used to reduce damage, then substrate damage is reduced, but etch directionality deteriorates
Solution Approach 1:
The patent introduces fluorinated passivation layers as intermediary protective layers during the etch process. These layers form on sidewalls during fluorine exposure and protect against lateral etching, providing directionality control without requiring high temperatures. The fluorinated layers act as a mediator between the etch chemistry and the physical structure, enabling low-temperature directional etching
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 results in a high-directional etch that minimizes pattern loading and arcing, enabling uniform etching through stacked layers of silicon nitride and silicon oxide with improved control over etch profiles and reduced damage to delicate structures.
Implementation Method 1
forming plasma effluents of the fluorine-containing precursor and the hydrogen-containing precursor
Implementation Method 2
contacting the substrate with the plasma effluents of the fluorine-containing precursor and the hydrogen-containing precursor. The contacting may form a fluorinated portion of the stacked layers
Implementation Method 3
forming plasma effluents of the inert precursor
Implementation Method 4
contacting the substrate with the plasma effluents of the inert precursor. The contacting may remove the fluorinated portion of the stacked layers
Data Source
AI summary
Exemplary semiconductor processing methods may include flowing a fluorine-containing precursor and a hydrogen-containing precursor into a processing region of a semiconductor processing chamber. A substrate may be positioned within the processing region. The substrate may include a trench formed through stacked layers including alternating layers of silicon nitride and silicon oxide. The methods may include forming plasma effluents of the fluorine-containing precursor and the hydrogen-containing precursor and contacting the substrate with the plasma effluents of the fluorine-containing precursor and the hydrogen-containing precursor to form a fluorinated portion of the stacked layers. The methods may include flowing an inert precursor into the processing region, forming plasma effluents of the inert precursor, and contacting the substrate with the plasma effluents of the inert precursor to remove the fluorinated portion of the stacked layers. The methods may be performed at a temperature of less than or about 20° C.