Silicon Nitride Etching Composition for High SiNx/SiOx Selectivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing etching processes for semiconductor fabrication have low selectivity for removing silicon nitride (SiNx) relative to silicon or silicon oxide, which is inadequate for advanced 3D NAND memory technology, and there is a need to further suppress the etch rate of silicon oxide (SiOx) to achieve higher selectivity.
Innovation Solution
An etching composition comprising phosphoric acid and a silicon-containing compound, specifically formulated to selectively remove silicon nitride over silicon oxide, with the silicon-containing compound having specific formulas (I, II, III) and the etching composition including an aqueous solvent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional hot phosphoric acid etching is used at 160°C, then silicon nitride can be removed, but the selectivity relative to silicon or silicon oxide is low
Solution Approach 1:
The patent modifies the chemical composition parameters of the etching solution by adding silicon-containing compounds (such as tetraethyl orthosilicate, trimethyl orthosilicate, or silane) to phosphoric acid. This changes the etching chemistry to preferentially attack silicon nitride while protecting silicon oxide. The silicon-containing compounds react with phosphoric acid to form species that selectively etch SiNx, achieving over 100:1 selectivity while maintaining effective SiNx removal rates.
Solution Approach 2:
The etching solution is formulated as a composite system combining phosphoric acid with silicon-containing compounds. This composite composition creates a synergistic effect where the phosphoric acid provides the base etching capability and the silicon-containing compounds modify the etching selectivity. The combination produces a solution that simultaneously achieves high SiNx etch rate and high selectivity against SiOx, resolving the contradiction between removal efficiency and material selectivity.
2Reliability
If etching selectivity is increased to protect silicon oxide, then the etch rate of silicon nitride may be reduced
Solution Approach 1:
The patent optimizes the concentration parameters of silicon-containing compounds in the etching solution (typically 0.1-10% by weight) to achieve the desired balance. By carefully controlling these composition parameters, the solution maintains high SiNx etch rates (e.g., 50-200 nm/min) while simultaneously achieving high selectivity (100:1 or greater) against SiOx etching. The parameter optimization ensures both productivity and selectivity requirements are met.
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 etching composition achieves a high selectivity for silicon nitride over silicon oxide, significantly reducing the etch rate of silicon oxide while maintaining a high etch rate for silicon nitride, thereby enhancing the precision and reliability of semiconductor fabrication processes.
Implementation Method 1
an etching composition which includes: (A) phosphoric acid; and (B) a mixture that includes a silicon-containing compound and an aqueous solvent
Data Source
AI summary
The disclosed and claimed subject matter is directed to an etching composition that includes (A) phosphoric acid and (B) a mixture that includes (i) a silicon-containing compound and (ii) an aqueous solvent. In some embodiments, the etching compositions include additional ingredients. The etching compositions are useful for the selective removal of silicon nitride over silicon oxide from a microelectronic device having such material(s) thereon during its manufacture.