Selective Nitride Etchant Composition for EFH-Stable Oxide Protection
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Solution Overview
Problem
Current etching processes for semiconductor manufacturing face challenges in achieving high selectivity for nitride films over oxide films, often resulting in defects, particle generation, and deterioration of device characteristics due to the use of phosphoric acid, which affects the effective field oxide height (EFH) and requires additional processes.
Innovation Solution
A composition comprising a first inorganic acid, an organic phosphite or hypophosphite as additives, and a silane inorganic acid salt, which provides high etch selectivity for nitride films while minimizing oxide film etching, preventing particle generation and maintaining device characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If phosphoric acid is used for wet etching of nitride film, then etching capability is improved, but etch selectivity between nitride film and oxide film deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the etching solution by replacing phosphoric acid with a combination of hydrofluoric acid and boric acid. This parameter change achieves high etch selectivity (oxide etch rate suppressed to 0.001-0.1 nm/min while nitride etch rate maintained at 0.1-10 nm/min) without requiring additional process steps.
Solution Approach 2:
Boric acid acts as an intermediary substance that suppresses the etching of oxide films while allowing effective etching of nitride films. The boric acid molecules interact with the etching system to selectively inhibit oxide removal, enabling high selectivity without sacrificing nitride etching capability.
2Productivity
If phosphoric acid is used for nitride film removal, then nitride film etching is improved, but device characteristics deteriorate due to EFH changes
Solution Approach 1:
The patent converts the potential harm of oxide film etching into a benefit by using hydrofluoric acid combined with boric acid. The boric acid specifically suppresses oxide etching while allowing nitride etching to proceed, thus eliminating the harmful effect on EFH while maintaining productivity in nitride film removal.
3Stability of the object's composition
If deionized water is added to phosphoric acid to prevent etch rate decrease, then etch rate stability is improved, but particle generation increases
Solution Approach 1:
The patent replaces the problematic phosphoric acid-based solution with a hydrofluoric acid and boric acid-based solution that does not require stabilization with deionized water. This new composition maintains etch rate stability inherently without generating particles, eliminating the need for additional water addition and avoiding the associated particle generation problem.
4Productivity
If phosphoric acid and hydrofluoric acid are used together, then nitride film etching is improved, but oxide film etching increases
Solution Approach 1:
The patent modifies the chemical composition parameters by introducing boric acid to the hydrofluoric acid system. This parameter change creates a selective etching environment where oxide etch rate is suppressed to 0.001-0.1 nm/min while nitride etch rate is maintained at 0.1-10 nm/min, achieving both high productivity and precision.
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 enables selective etching of nitride films with high selectivity, allowing for precise regulation of the effective field oxide height (EFH) and preventing damage to oxide films, thereby enhancing device characteristics and process stability.
Implementation Method 1
a composition for selective etching of a nitride film with respect to an oxide film includes a first inorganic acid including any one selected from the group consisting of sulfuric acid, nitric acid, phosphoric acid, silicic acid, hydrofluoric acid, boric acid, hydrochloric acid, perchloric acid, and mixtures thereof
Data Source
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AI summary
A composition for etching and a method of manufacturing a semiconductor device, the method including an etching process of using the composition for etching, are provided. The composition for etching includes a first inorganic acid; any one first additive selected from the group consisting of phosphorous acid, an organic phosphite, a hypophosphite, and mixtures thereof; and a solvent. The composition for etching is a high-selectivity composition for etching that can selectively remove a nitride film while minimizing the etch rate for an oxide film and does not have a problem such as particle generation, which adversely affects device characteristics.