Silicon Nitride Etching Selectivity via Chelating Agent
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Solution Overview
Problem
Conventional etching compositions for silicon nitride layers face challenges such as abnormal growth of the silicon oxide layer, particle formation on the wafer surface, and instability in semiconductor manufacturing processes due to excessive bubble generation.
Innovation Solution
An etching composition comprising phosphoric acid, a silicon-based compound represented by Formula 1, and water, which selectively etches silicon nitride layers with high selectivity compared to silicon oxide layers, while minimizing abnormal growth and particle formation, and maintaining process stability by reducing bubble generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phosphoric acid is used to etch silicon nitride layers, then the etching process can be performed, but abnormal growth of silicon oxide layer occurs due to increased silicon ion concentration
Solution Approach 1:
A chelating agent is introduced as an intermediary substance that binds to silicon ions released during etching, preventing them from participating in autoprotolysis reactions that cause abnormal oxide growth. The chelating agent acts as a mediator between the etching process and the oxide layer stability.
Solution Approach 2:
The pH of the etching composition is precisely controlled and maintained within a specific range (2-4) to optimize the etching rate of silicon nitride while minimizing the etching rate of silicon oxide and preventing abnormal oxide growth through controlled chemical conditions.
2Manufacturing precision
If deionized water is supplied to control phosphoric acid concentration, then etching selectivity can be maintained, but particle formation occurs on wafer surface
Solution Approach 1:
The chelating agent serves as an intermediary that captures silicon ions in solution, preventing them from precipitating as particles on the wafer surface while maintaining the desired etching selectivity through controlled chemical interactions.
Solution Approach 2:
The chelating agent is consumed during the etching process to bind silicon ions, effectively removing them from the solution before they can form particles, thereby maintaining solution cleanliness and wafer surface quality.
3Manufacturing precision
If sulfuric acid is added to phosphoric acid to reduce silicon oxide etching rate, then selectivity improves, but production efficiency decreases due to reduced silicon nitride etching rate
Solution Approach 1:
Instead of changing the chemical composition by adding sulfuric acid, the pH parameter of the phosphoric acid solution is precisely controlled within the range of 2-4, which independently optimizes both selectivity and etching rate without compromising production efficiency.
Solution Approach 2:
The harmful effect of silicon oxide etching is eliminated by removing excess phosphoric acid through controlled water supply and pH adjustment, rather than adding substances that would suppress silicon nitride etching, thereby maintaining high production efficiency.
4Manufacturing precision
If hydrofluoric acid is added to improve silicon nitride etching selectivity, then selectivity increases, but silicon oxide layer is also etched excessively
Solution Approach 1:
The pH of the phosphoric acid solution is precisely controlled within the range of 2-4, creating chemical conditions that favor silicon nitride etching while inherently suppressing silicon oxide etching, eliminating the need for hydrofluoric acid and its associated harmful effects.
Solution Approach 2:
The chelating agent acts as an intermediary that selectively binds silicon ions from silicon nitride etching, preventing them from attacking the silicon oxide layer, thereby protecting the oxide layer while maintaining high nitride etching selectivity.
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 high etching selectivity for silicon nitride layers, prevents abnormal growth of the silicon oxide layer, minimizes particle formation, and ensures process stability by reducing bubble generation, thereby enabling the manufacture of semiconductor devices with consistent quality.
Implementation Method 1
the silicon nitride layer reacts with phosphoric acid and changes into the form of H2SiO3
Implementation Method 2
an etching composition that may selectively etch a silicon nitride layer as compared to a silicon oxide layer
Data Source
AI summary
The present disclosure relates to an etching composition for a silicon nitride layer, and the etching composition for a silicon nitride layer has a significantly excellent etching selectivity for a silicon nitride layer as compared to a silicon oxide layer, prevent abnormal growth of the silicon oxide layer, suppresses particle generation affecting characteristics of a semiconductor device, and has an excellent effect of a significantly small generation height of bubbles.