Etchant Composition for Silicon Nitride Selectivity
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Solution Overview
Problem
Existing etchant compositions for silicon nitride films in semiconductor manufacturing lack high selectivity over silicon oxide films, leading to damage, re-growth of silicon oxide films, and defects in etching processes, particularly when using hydrofluoric acid or low solubility compounds.
Innovation Solution
An etchant composition containing phosphoric acid, a compound expressed by Chemical Formula 1 or 2, a silicone compound, and an amino acid compound, with specific weight percentages, which maintains high selectivity and prevents re-growth of silicon oxide films during the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydrofluoric acid is included in the etchant to increase etching capability, then the etching rate improves, but the selectivity to silicon nitride film deteriorates and silicon oxide film is damaged
Solution Approach 1:
The patent removes hydrofluoric acid from the etchant composition entirely, replacing it with phosphoric acid as the primary etching agent. This extraction of the harmful component eliminates the damage to silicon oxide film while maintaining etching capability through alternative chemistry.
Solution Approach 2:
The patent changes the chemical composition parameters by using phosphoric acid with specific concentration ratios (70-90 wt%) and adding small amounts of silicon-fluorine compounds (0.1-5 wt%). This parameter change achieves high selectivity (2000:1 or higher) while maintaining effective etching rate.
2Stability of the object's composition
If deionized water is added to the phosphoric acid mixture to maintain etching rate, then etching performance is stabilized, but process control becomes sensitive and defects occur
Solution Approach 1:
The patent optimizes the water content parameter to a specific range (10-40 wt%) in the phosphoric acid mixture. This parameter optimization provides a stable etching rate while reducing sensitivity to process variations, achieving both composition stability and manufacturing precision.
3Productivity
If oxime silane is added to the phosphoric acid composition to etch silicon nitride film, then etching capability is enhanced, but solubility decreases causing particle generation
Solution Approach 1:
The patent replaces oxime silane with silicon-fluorine compounds that have better solubility characteristics. The silicon-fluorine compounds provide the necessary etching capability without the solubility problems, preventing particle generation on the substrate.
Solution Approach 2:
The patent creates a composite etchant system combining phosphoric acid with silicon-fluorine compounds and amino acid compounds. This composite composition achieves enhanced etching capability while maintaining good solubility and preventing particle generation.
4Reliability
If silicon oxide film etching inhibitors such as silicate or fluorosilicic acid are added to increase selective etching rate, then selectivity improves, but silicon concentration increases causing re-growth of silicon oxide film
Solution Approach 1:
The patent removes traditional silicon oxide film etching inhibitors (silicate, fluorosilicic acid) from the composition. Instead, it uses phosphoric acid combined with silicon-fluorine compounds and amino acid compounds to achieve high selectivity without causing re-growth issues.
Solution Approach 2:
The patent employs a composite system of phosphoric acid, silicon-fluorine compounds, and amino acid compounds that work synergistically to provide selective etching while preventing silicon oxide film re-growth through controlled chemistry.
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 composition achieves a selectivity of 2000:1 or higher between silicon nitride and silicon oxide films, minimizing damage to silicon oxide films and maintaining a constant etching rate without re-growth over time.
Implementation Method 1
the silicon nitride film may be removed by wet etching process that uses an etchant or etchant composition containing phosphoric acid
Implementation Method 2
an etchant composition with a high selectivity to a silicon nitride film, which etches a silicon nitride film with a selectivity of 2000:1 or higher between the silicon nitride film and a silicon oxide film
Data Source
AI summary
Provided is an etchant composition for a silicon nitride film, and more particularly, to an etchant composition with a high selectivity to a silicon nitride film, which is used to etch away a silicon nitride film in semiconductor process and which selectively has a high etching rate for the silicon nitride film compared to a silicon oxide film in a high temperature etch process, in which the etchant composition with the high selectivity selectively etches the silicon nitride film at a selectivity of 2000:1 or higher between the silicon nitride film and the silicon oxide film which are in a stack structure, and minimizes damages to the silicon oxide film and etching rate, and does not cause re-growth of the silicon oxide film over the process time.