Etching Method Gas Flow Control
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Solution Overview
Problem
Conventional parallel plate plasma etching apparatuses lack a consistent and reliable method for determining the optimal flow rate ratio of gases supplied to the central and peripheral parts of a substrate during etching processes, particularly when using CF-based gases, leading to inefficiencies in surface uniformity and etching characteristics.
Innovation Solution
An etching method that controls the flow rate of processing gases containing carbon and halogen, with a carbon number of two or less supplied more to the central portion and three or more to the peripheral portion, or vice versa, using a gas supply unit with independent control over the central and peripheral regions to achieve uniform etching characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single gas flow rate is supplied uniformly across the entire substrate surface, then the apparatus operation is simple, but the in-surface uniformity of etching characteristics deteriorates
Solution Approach 1:
The gas supply unit is divided into a central portion and a peripheral portion, allowing independent control of gas flow rates to different regions of the substrate. This segmentation enables optimized etching uniformity across the substrate surface by addressing the different gas distribution requirements of central and peripheral areas.
Solution Approach 2:
Different gas flow rates are supplied to the central and peripheral portions of the substrate based on their specific etching requirements. The gas flow rate to the central portion is set differently from that to the peripheral portion, creating local quality variations that improve overall etching uniformity.
2Manufacturing precision
If different gas flow rates are supplied to central and peripheral portions, then the in-surface uniformity of etching characteristics is improved, but the device complexity increases
Solution Approach 1:
The gas supply unit is segmented into central and peripheral gas injection openings, with separate flow rate control for each segment. This segmentation allows precise control of gas distribution while maintaining a relatively simple overall apparatus structure.
Solution Approach 2:
The gas supply unit serves multiple functions: it supplies processing gas to both central and peripheral regions, and independently controls flow rates to each region. This multi-functionality reduces the need for separate complex control systems for each function.
3Manufacturing precision
If trial-and-error methods are used to determine optimal gas flow rate ratios, then the etching uniformity can be improved, but the time and effort required increase significantly
Solution Approach 1:
The patent establishes predetermined relationships between gas flow rate ratios and etching characteristics based on the carbon numbers of the gases used. This preliminary establishment of optimal parameters eliminates the need for time-consuming trial-and-error processes during actual production.
Solution Approach 2:
The patent provides a systematic method for determining optimal gas flow rate ratios based on the carbon numbers of the processing gases, creating a feedback mechanism that guides parameter selection without requiring extensive experimental iteration.
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
This approach enhances in-surface uniformity of etching rates and processing accuracy by optimizing gas distribution, reducing the need for trial-and-error methods and improving the consistency of etching results.
Implementation Method 1
a plasma of the processing gas is generated, whereby an etching process is performed on, e.g., a semiconductor wafer
Implementation Method 2
active species of CF, which are produced when the CF-based gas is converted into a plasma, cause both the etching and the polymerization
Implementation Method 3
a hole (recess) is formed by an etching action of an etchant together with polymerization which forms polymer on a sidewall of the hole to protect the sidewall
Data Source
AI summary
When a substrate is etched by using a processing gas including a first gas containing halogen and carbon and having a carbon number of two or less per molecule, while supplying the processing gas toward the substrate independently from a central and a peripheral portion of a gas supply unit, which face the central and the periphery part of the substrate respectively, the processing gas is supplied such that a gas flow rate is greater in the central portion than in the peripheral portion. When the substrate is etched by using a processing gas including a second gas containing halogen and carbon and having a carbon number of three or more per molecule, the processing gas is supplied such that a gas flow rate is greater in the peripheral portion than in the central portion.