Phosphoric Acid Etchant with Silane Compound for Nitride Selectivity
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Solution Overview
Problem
Conventional etchant compositions for removing nitride films in semiconductor manufacturing often result in reduced etching selectivity between nitride and oxide films, leading to defects and particle formation, which affect device characteristics and require additional processing steps.
Innovation Solution
An etchant composition comprising phosphoric acid and a silane compound with specific chemical structures, which selectively etches nitride films while minimizing oxide film etching and preventing particle formation, by forming a protective film on the oxide surface to enhance selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If phosphoric acid and deionized water mixture is used for nitride film etching, then etching rate is maintained, but etching selectivity to oxide film deteriorates and defects arise
Solution Approach 1:
The patent changes the chemical composition parameters of the etchant by replacing deionized water with a specific organic solvent (alcohol or ether) and adjusting the phosphoric acid concentration to 70-99.9 wt%, thereby improving etching selectivity between nitride and oxide films while reducing defect formation
Solution Approach 2:
The patent uses readily available organic solvents (alcohols or ethers) as replacements for deionized water, employing inexpensive, easily handled materials that provide superior etching performance without the defects associated with conventional water-based etchants
2Productivity
If fluoric acid or nitric acid is added to phosphoric acid for nitride film removal, then etching rate increases, but etching selection ratio between nitride film and oxide film deteriorates
Solution Approach 1:
The patent changes the etchant composition by using pure phosphoric acid or phosphoric acid with organic solvent additives, avoiding the use of fluoric acid or nitric acid. This parameter change maintains high etching rate while preserving excellent selectivity between nitride and oxide films
3Manufacturing precision
If silicic acid or silicate is used as additive in phosphoric acid etchant, then etching performance is enhanced, but particle formation occurs affecting substrate
Solution Approach 1:
The patent replaces silicic acid or silicate additives with simple organic solvents (alcohols or ethers) that do not cause particle formation. These inexpensive organic additives enhance etching performance without generating harmful particles on the substrate
Solution Approach 2:
The patent converts the potential harm of particle-forming additives into a beneficial solution by using organic solvents that provide etching enhancement without particle generation, thereby eliminating the harmful effect while maintaining the benefit of improved etching performance
4Productivity
If phosphoric acid etchant is used for nitride film removal, then nitride film is etched, but oxide film is also etched due to reduced selection ratio, making EFH adjustment difficult
Solution Approach 1:
The patent changes the etchant composition to phosphoric acid with organic solvent (alcohol or ether) additives, which maintains high nitride film etching rate while significantly improving oxide film resistance. This parameter change enables precise control of effective field oxide height by allowing sufficient etching time for nitride removal without excessive oxide etching
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 etchant composition achieves a high selection ratio for nitride film etching over oxide film etching, preventing particle formation and improving device characteristics by using a silane compound with multiple silane groups that effectively protects the oxide film.
Implementation Method 1
the silane compound according to claim 1, as an additive for an etchant composition... may be reacted with a surface of an oxide film to form a protective film capable of protecting the oxide film
Implementation Method 2
An etchant composition comprising phosphoric acid and a silane compound... selectively etches nitride films while minimizing oxide film etching
Data Source
AI summary
An etchant composition includes phosphoric acid and a silane compound represented by the following Chemical Formula 1:wherein A is an n-valent radical, L is C1-C5 hydrocarbylene, R1 to R3 are independently hydrogen, hydroxy, hydrocarbyl, or alkoxy, in which R1 to R3 exist respectively or are connected to each other by a heteroelement, and n is an integer of 2 to 5.