Cyclic Plasma Etching of Oxide-Nitride Stacks for HAR Contacts
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Solution Overview
Problem
Conventional etching processes struggle to efficiently and uniformly etch alternating layers of silicon nitride and silicon oxide in semiconductor structures, often leading to non-uniform profiles and arcing issues due to the use of polymeric passivation materials and plasma damage.
Innovation Solution
A cyclic etching process using a fluorine-containing precursor followed by a phosphorous-and-fluorine-containing precursor is employed, which selectively etches silicon nitride and silicon oxide without the need for polymeric passivation, maintaining high directionality and reducing arcing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet HF etch is used to preferentially remove silicon oxide, then etch selectivity is improved, but penetration ability into constrained trenches deteriorates and material deformation occurs
Solution Approach 1:
The patent changes the physical state of the etching process from wet to dry plasma etching, and further modifies the chemical composition by using fluorine-containing precursors with carbon-free formulations. This parameter change enables the etch process to penetrate constrained trenches effectively while maintaining high selectivity between silicon oxide and silicon nitride layers, avoiding the deformation issues associated with wet etching.
Solution Approach 2:
The patent employs a composite approach by combining fluorine-containing precursors with specific process conditions to create a plasma chemistry that exhibits both high etch selectivity and excellent penetration ability. The carbon-free fluorine-containing precursor formulation works synergistically with the plasma process to achieve uniform etching through high aspect ratio contacts without the drawbacks of traditional wet or conventional dry etching methods.
2Object-affected harmful factors
If local plasma is used to penetrate constrained trenches, then penetration ability is improved, but substrate damage through electric arcs worsens
Solution Approach 1:
The patent modifies the plasma process parameters by using carbon-free fluorine-containing precursors and controlling the plasma chemistry to prevent arc formation. This parameter change maintains the penetration ability of dry plasma etching into constrained trenches while eliminating the substrate damage caused by electric arcs, achieving a stable and controlled etching process.
Solution Approach 2:
The patent uses a carbon-free fluorine-containing precursor formulation that avoids the formation of polymeric residues and arc-generating conditions. This approach replaces the need for complex arc suppression mechanisms with a simpler, carbon-free chemistry that inherently prevents arc formation, reducing substrate damage while maintaining effective trench penetration.
3Object-generated harmful factors
If polymeric passivation materials are used in etching processes, then sidewall protection is improved, but pattern loading and arcing issues worsen
Solution Approach 1:
The patent extracts and eliminates the carbon-containing polymeric passivation materials from the etching process by using carbon-free fluorine-containing precursors. This removal of polymeric materials eliminates the source of pattern loading and arcing issues while still providing adequate sidewall protection through the controlled plasma chemistry, achieving clean etching without harmful byproducts.
Solution Approach 2:
The patent changes the chemical composition parameters of the etching precursor from carbon-containing to carbon-free fluorine-containing formulations. This parameter change fundamentally alters the etching chemistry to prevent polymeric material formation, thereby eliminating pattern loading and arcing issues while maintaining effective sidewall protection through the modified plasma process.
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 process achieves uniform etching of alternating layers with high selectivity and directionality, minimizing pattern loading and arcing, thereby improving the quality of semiconductor structures.
Implementation Method 1
forming plasma effluents of the fluorine-containing precursor
Implementation Method 2
The contacting may selectively etch an exposed portion of silicon nitride
Implementation Method 3
forming plasma effluents of the fluorine-containing precursor and the phosphorous-and-fluorine-containing precursor
Implementation Method 4
The contacting may selectively etch an exposed portion of silicon oxide
Data Source
AI summary
Exemplary semiconductor processing methods may include flowing a fluorine-containing precursor into a processing region of a semiconductor processing chamber. A substrate may be positioned within the processing region. The substrate may include alternating layers of silicon nitride and silicon oxide. The methods may include forming plasma effluents of the fluorine-containing precursor. The methods may include contacting the substrate with the plasma effluents of the fluorine-containing precursor. The contacting may selectively etch an exposed portion of silicon nitride. The methods may include introducing a phosphorous-and-fluorine-containing precursor into the processing region of the semiconductor processing chamber while maintaining a flow of the fluorine-containing precursor. The methods may include forming plasma effluents of the fluorine-containing precursor and the phosphorous-and-fluorine-containing precursor. The methods may include contacting the substrate with the plasma effluents of the fluorine-containing precursor and the phosphorous-and-fluorine-containing precursor. The contacting may selectively etch an exposed portion of silicon oxide.