Silicon Oxide Etching Gas Chemistry for Uniform Surface Flatness
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Solution Overview
Problem
Existing etching methods for silicon oxide films on semiconductor wafers result in uneven surface flatness due to variations in reaction product formation and collision probabilities of etching gases, leading to convex or concave shapes that degrade semiconductor device performance.
Innovation Solution
An etching method using a combination of halogen-containing, ammonia, and amine gases, with controlled gas supply cycles and pressure conditions, to achieve uniform etching and high surface flatness of silicon oxide films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single type of etching gas is supplied to the silicon oxide film, then the etching process is simple, but the surface flatness becomes uneven due to variations in reaction product formation and gas collision probabilities
Solution Approach 1:
The patent combines multiple types of etching gases (halogen-containing gas, ammonia gas, and amine gas) into a single etching atmosphere to simultaneously achieve uniform etching across the silicon oxide film surface and maintain process simplicity. This merging approach allows different gases to complement each other's functions, with halogen-containing gases providing etching capability and ammonia/amine gases regulating reaction product formation, thereby resolving the contradiction between process simplicity and surface flatness uniformity.
Solution Approach 2:
The patent changes the compositional parameters of the etching gas mixture by introducing multiple gas types with different chemical properties. Specifically, it controls the ratios of halogen-containing gas, ammonia gas, and amine gas to optimize the etching uniformity and surface flatness. This parameter adjustment allows the system to achieve desired etching results while maintaining controlled reaction conditions throughout the etching process.
2Productivity
If etching gases are supplied continuously, then the etching speed is high, but the reaction product formation becomes uneven leading to convex or concave shapes on the etched surface
Solution Approach 1:
The patent implements periodic action by sequentially controlling the supply of different etching gases during the etching process. It alternates between supplying halogen-containing gas for etching and ammonia/amine gases for reaction product management, creating a cyclic etching pattern that prevents excessive reaction product accumulation and ensures uniform surface morphology while maintaining high etching speed.
Solution Approach 2:
The patent maintains continuous useful action by ensuring that etching and reaction product management occur simultaneously through the continuous supply of a multi-component gas mixture. The halogen-containing gas continuously provides etching capability while ammonia and amine gases continuously regulate reaction product formation, ensuring both high productivity and uniform surface shape throughout the etching process.
3Productivity
If halogen-containing gas alone is used for etching, then the etching rate is high, but the surface flatness deteriorates due to excessive reaction product formation
Solution Approach 1:
The patent introduces ammonia gas and amine gas as intermediary substances that mediate between the halogen-containing gas and the silicon oxide film. These intermediary gases regulate the formation and removal of reaction products, preventing excessive accumulation that would otherwise degrade surface flatness. They act as buffers that maintain etching rate while ensuring uniform surface morphology.
Solution Approach 2:
The patent creates a composite etching atmosphere by combining halogen-containing gas, ammonia gas, and amine gas in specific ratios. This composite gas mixture synergistically combines the high etching rate capability of halogen-containing gases with the surface-flatness-preserving properties of ammonia and amine gases, achieving both high productivity and high manufacturing precision simultaneously.
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 method ensures a desired shape and high flatness of etched silicon oxide films, preventing performance degradation in semiconductor devices by balancing reaction product formation and gas collisions, thereby enhancing manufacturing quality.
Implementation Method 1
etching a silicon oxide film by supplying a halogen-containing gas, an ammonia gas, and an amine gas as etching gases
Implementation Method 2
whereby the reaction products are made to sublime
Data Source
Figure 1
Figure 2A~2D
Figure 3A~3B
AI summary
An etching method according to the present disclosure includes an etching step in which a halogen-containing gas, an ammonia gas, and an amine gas are supplied as etching gases to a substrate including a silicon oxide film formed on a surface of the substrate, and the silicon oxide film is etched.