Selective Silicon Oxide Etching in Laminated Semiconductor Films
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Solution Overview
Problem
Current micromachining processing agents fail to selectively etch silicon oxide films without etching silicon nitride and silicon alloy films, leading to difficulties in patterning and processing semiconductor devices with laminated films.
Innovation Solution
A micromachining processing agent containing hydrogen fluoride, ammonium fluoride, a water-soluble polymer, and an organic compound with a carboxyl group, which allows for selective etching of silicon oxide films while suppressing etching of silicon nitride and silicon alloy films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If buffered hydrofluoric acid or hydrofluoric acid is used as a micromachining processing agent, then the silicon oxide film can be etched, but the silicon nitride film and silicon alloy film are etched simultaneously, making it difficult to pattern the structure in a desired shape
Solution Approach 1:
The patent changes the chemical composition parameters of the etching solution by adding specific additives (anionic surfactant and water-soluble polymer) to hydrofluoric acid, transforming it from a non-selective etchant into a selective etching agent that differentiates between silicon oxide, silicon nitride, and silicon alloy films based on their chemical properties
Solution Approach 2:
The patent introduces intermediary substances (anionic surfactant and water-soluble polymer) that mediate the etching process. These additives adsorb onto specific film surfaces, creating a protective barrier that prevents the hydrofluoric acid from etching silicon nitride and silicon alloy films while allowing selective etching of silicon oxide film
2Manufacturing precision
If an anionic surfactant such as ammonium lauryl sulfate is added to hydrofluoric acid to achieve selective etching of silicon oxide film, then the silicon nitride film can be protected, but the foaming property becomes extremely large, making it unsuitable for semiconductor production
Solution Approach 1:
The patent merges multiple functional additives (anionic surfactant for selectivity and water-soluble polymer for foam control) into a single etching solution formulation, allowing the solution to simultaneously achieve selective etching while maintaining acceptable foaming properties for industrial application
Solution Approach 2:
The patent uses a water-soluble polymer that can replicate the foam-suppressing function of other additives while being specifically compatible with the hydrofluoric acid-based etching system, providing both selective etching capability and controlled foaming characteristics
3Productivity
If conventional etching liquids are used to remove the silicon oxide film, then the silicon oxide film can be etched, but the silicon nitride film and silicon alloy film are particularly etched, reducing processing accuracy
Solution Approach 1:
The patent modifies the chemical parameters of the etching solution by adding specific concentrations of anionic surfactant and water-soluble polymer to hydrofluoric acid, creating a new composition that maintains high etching efficiency for silicon oxide while introducing selectivity to protect silicon nitride and silicon alloy films from unintended 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 solution enables precise micromachining of silicon oxide films while preventing etching of silicon nitride and silicon alloy films, improving the accuracy and yield in semiconductor device production.
Implementation Method 1
a micromachining processing agent containing: (a) hydrogen fluoride in an amount of 0.01 to 50 mass % with respect to a total mass of the micromachining processing agent; (b) ammonium fluoride in an amount of 0.1 to 40 mass % with respect to a total mass of the micromachining processing agent
Implementation Method 2
a water-soluble polymer in an amount of 0.001 to 10 mass % with respect to a total mass of the micromachining processing agent... the silicon nitride film is not particularly etched
Implementation Method 3
an organic compound having a carboxyl group in an amount of 0.001 to 1 mass % with respect to a total mass of the micromachining processing agent... micromachining of the silicon alloy film is suppressed
Data Source
AI summary
A micromachining processing agent and a micromachining processing method capable of selectively micromachining a silicon oxide film when a laminated film including at least a silicon nitride film, a silicon oxide film, and a silicon alloy film is micromachined. The micromachining processing agent is used for micromachining of a laminated film including at least a silicon oxide film, a silicon nitride film, and a silicon alloy film. The micromachining processing agent contains: (a) 0.01 to 50 mass % of hydrogen fluoride; (b) 0.1 to 40 mass % of ammonium fluoride; (c) 0.001 to 10 mass % of a water-soluble polymer; (d) 0.001 to 1 mass % of an organic compound having a carboxyl group; and (e) water as an optional component, in which the water-soluble polymer is at least one selected from a group consisting of acrylic acid, ammonium acrylate, acrylamide, styrenesulfonic acid, ammonium styrenesulfonate, and styrenesulfonic acid ester.