Selective Silicon Nitride Etching via Fluorine and Suppressant
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Solution Overview
Problem
Current etching methods for semiconductor processes face challenges in achieving high selectivity and precision in removing silicon nitride without damaging substrate features, as wet etching consumes large chemicals and high-energy plasma etching methods can cause ion bombardment damage.
Innovation Solution
A gas-phase chemistry method involving a fluorine-containing precursor and a silicon-containing suppressant is used to selectively etch silicon nitride, maintaining a water-free environment and controlling temperature and flow rates to achieve high selectivity over silicon oxide and silicon, preventing feature damage from ion bombardment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet HF etching is used to remove silicon oxide, then selectivity for silicon oxide over other dielectrics is improved, but penetration into constrained trenches is poor and material deformation occurs
Solution Approach 1:
The patent changes the physical state of the etching medium from liquid (wet HF) to gas phase (anhydrous HF vapor), enabling the etchant to penetrate constrained trenches effectively while maintaining high selectivity for silicon oxide removal
Solution Approach 2:
The patent replaces the wet chemical etching mechanism with a gas-phase chemical etching mechanism, where anhydrous HF vapor delivers fluorine atoms to etch silicon oxide without the limitations of liquid penetration and material deformation
2Ease of operation
If local plasma etching is used to penetrate constrained trenches, then trench penetration capability is improved, but substrate damage occurs through electric arc discharge
Solution Approach 1:
The patent replaces plasma-based physical/chemical etching with pure gas-phase chemical etching using anhydrous HF vapor, eliminating ion bombardment and electric arc discharge while maintaining effective trench penetration capability
Solution Approach 2:
The patent uses anhydrous HF vapor in a controlled gas-phase environment that avoids the harmful effects of plasma discharge, providing a non-ionizing etching mechanism that prevents substrate damage
3Productivity
If conventional etching methods are used to remove silicon nitride, then etching capability is achieved, but selectivity over silicon oxide and silicon is insufficient
Solution Approach 1:
The patent introduces a silicon-containing suppressant as an intermediary substance that selectively suppresses etching of silicon oxide and silicon while allowing anhydrous HF to etch silicon nitride, achieving high selectivity through chemical mediation
Solution Approach 2:
The patent applies different chemical environments to different materials on the substrate: anhydrous HF vapor provides fluorine atoms that react with silicon nitride, while the silicon-containing suppressant creates a protective layer on silicon oxide and silicon surfaces, achieving material-specific etching behavior
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 method enables fast and selective etching of silicon nitride with high selectivity over silicon oxide and silicon, reducing chemical consumption and preventing feature damage, suitable for advanced semiconductor devices like VNAND.
Implementation Method 1
flowing a fluorine-containing precursor into a processing region of a semiconductor processing chamber... contacting a substrate with the fluorine-containing precursor and the silicon-containing suppressant... selectively etching the exposed region of silicon nitride
Implementation Method 2
The processing region of the semiconductor processing chamber may be maintained water-free while contacting the substrate with the fluorine-containing precursor and the silicon-containing suppressant
Data Source
AI summary
Exemplary methods for selective etching of semiconductor materials may include flowing a fluorine-containing precursor into a processing region of a semiconductor processing chamber. The methods may also include flowing a silicon-containing suppressant into the processing region of the semiconductor processing chamber. The methods may further include contacting a substrate with the fluorine-containing precursor and the silicon-containing suppressant. The substrate may include an exposed region of silicon nitride and an exposed region of silicon oxide. The methods may also include selectively etching the exposed region of silicon nitride to the exposed region of silicon oxide.