Fluorine Plasma Etching of Boron Layers With Carbon Selectivity
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Solution Overview
Problem
Conventional semiconductor processing technologies face challenges in uniformly removing boron-containing materials from substrates, leading to inconsistent patterning and etching profiles, particularly in 3D NAND structures, due to limited selectivity and etch rates, which can result in bowing and clogging of memory holes, affecting the uniformity and electrical performance of devices.
Innovation Solution
The use of a fluorine-containing precursor, such as nitrogen trifluoride (NF3), is employed to generate plasma effluents that selectively remove boron-containing materials from substrates with high selectivity relative to carbon-containing materials, maintaining the integrity of underlying structures and preventing undercut profiles, while maintaining controlled processing conditions like temperature and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to remove boron-containing material, then the etching process can proceed, but the selectivity relative to carbon-containing material is limited and etch rates are inconsistent
Solution Approach 1:
The patent changes the chemical parameters of the etching process by using fluorine-containing precursors (NF3, CF4, SF6) instead of conventional etchants. This chemical parameter change enables high selectivity (greater than 10:1) between boron-containing material and carbon-containing hardmask material, while maintaining consistent etch rates (greater than 5,000 Å/min) and uniformity throughout the etching process.
2Productivity
If high etch rates are achieved, then productivity improves, but uniformity of etching and patterning consistency deteriorate
Solution Approach 1:
The patent achieves both high productivity and high precision by changing to fluorine-based chemistry with controlled plasma parameters. The etch rate exceeds 5,000 Å/min while maintaining uniform patterning across the substrate, resolving the traditional trade-off between speed and quality in semiconductor etching processes.
Solution Approach 2:
The patent employs periodic pulsing of the fluorine-containing precursor during the etching process. This periodic action allows for controlled removal of boron-containing material at high rates while maintaining uniformity and preventing defects, achieving both high productivity and manufacturing precision.
3Loss of substance
If etching is performed to remove boron-containing material, then the material can be cleared, but bowing and clogging of memory holes may occur affecting uniformity
Solution Approach 1:
The patent changes the etching chemistry to fluorine-based precursors with optimized plasma conditions, enabling complete removal of boron-containing material without causing bowing or clogging of memory holes. This maintains the circularity and uniformity of memory holes throughout the etching process, achieving both complete material removal and structural integrity.
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 achieves efficient removal of boron-containing materials with high selectivity and rate, minimizing impact on underlying materials, ensuring uniformity and preventing clogging, thus improving the quality and uniformity of semiconductor structures and device performance.
Implementation Method 1
generating plasma effluents of the fluorine-containing precursor
Implementation Method 2
contacting the substrate with the plasma effluents of the fluorine-containing precursor. The methods may include removing the boron-containing material from the substrate
Data Source
AI summary
Exemplary methods of semiconductor processing may include providing a fluorine-containing precursor to a processing region of a semiconductor processing chamber. A substrate may be housed within the processing region. The substrate may include a boron-containing material overlying a carbon-containing material. The methods may include generating plasma effluents of the fluorine-containing precursor. The methods may include contacting the substrate with the plasma effluents of the fluorine-containing precursor. The methods may include removing the boron-containing material from the substrate.