Etching Composition Selectivity and Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current etching compositions for semiconductor manufacturing struggle with achieving a high selectivity ratio for nitride film removal while minimizing oxide film etching, often resulting in particle generation and storage stability issues, which can lead to defects and inefficiencies in the process.
Innovation Solution
An etching composition comprising phosphoric acid, a silane compound, and an ammonium salt represented by Formula 1, which includes a silane compound and an ammonium salt that provides structural stability and prevents particle formation, allowing for selective nitride film etching with minimal oxide film etching and maintaining stability over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If phosphoric acid and deionized water are used for wet etching of nitride film, then etching rate is maintained, but etching selectivity ratio to oxide film decreases and defects occur
Solution Approach 1:
The patent changes the chemical composition parameters of the etching solution by adding specific additives (silane compound and ammonium salt) to phosphoric acid-based etching solution. This modifies the etching characteristics to achieve high selectivity ratio (oxide film etching rate suppressed to 1/10 or less of nitride film) while maintaining adequate etching rate for nitride film removal.
2Manufacturing precision
If silicic acid or silicate is added to phosphoric acid for etching, then etching selectivity improves, but particles are generated that affect the substrate
Solution Approach 1:
The patent replaces conventional silicic acid/silicate additives with a silane compound that decomposes to form colloidal silica in situ. This approach uses a stable, non-particulate precursor (silane) that converts to the desired etching-modifying species (colloidal silica) only during the etching process, avoiding particle generation from adding solid silicate directly to the solution.
3Manufacturing precision
If silane-based additive is added to etching composition, then etching performance improves, but solubility is too low causing precipitation of particles
Solution Approach 1:
The patent creates a composite etching system combining phosphoric acid, silane compound, and ammonium salt. The ammonium salt acts as a solubilizing agent that keeps the silane compound dissolved at adequate concentrations. During etching, the silane decomposes and forms colloidal silica that remains dispersed without precipitating, providing both improved etching performance and compositional stability.
4Duration of action of stationary object
If conventional etching composition is stored for long period, then etching speeds change, but selection ratio varies adversely
Solution Approach 1:
The patent performs preliminary stabilization by adding ammonium salt to the etching composition before storage. This additive prevents decomposition and maintains constant etching characteristics throughout the storage period. The composition is designed to be stable from manufacture through storage and use, with etching rates and selectivity ratios remaining constant.
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 high selectivity ratio for nitride film etching with minimal oxide film etching, prevents particle formation, and maintains stability over storage, ensuring reliable semiconductor device manufacturing processes.
Implementation Method 1
In a wet etching process for removing the nitride film, a mixture of phosphoric acid and deionized water is generally used
Implementation Method 2
an etching composition including phosphoric acid and a silicic acid or a silicate
Data Source
AI summary
An etching composition includes phosphoric acid, a silane compound comprising at least one silicon (Si) atom, and an ammonium salt represented by Formula 1 below:wherein:L1 to L3 are independently substituted or unsubstituted hydrocarbylene,R1 to R4 are independently hydrogen, a substituted or unsubstituted hydrocarbyl group, andXn− is an n-valent anion, where n is an integer of 1 to 3.