Selective Silicon Oxide Etching via Fluorocarbon Deposit
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Solution Overview
Problem
Conventional etching methods for silicon oxide with respect to silicon nitride often result in unintended etching of the silicon nitride region due to the lack of protection during the etching process of silicon oxide, leading to inefficiencies in forming precise openings in electronic device manufacturing.
Innovation Solution
An etching method involving multiple sequences of plasma processing using a fluorocarbon gas, where the first sequence etches the silicon oxide with a lower amount and the subsequent sequences increase the etching amount, while forming a deposit to protect the silicon nitride region, allowing for selective etching of silicon oxide without significantly etching the silicon nitride.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional plasma etching is used to etch silicon oxide, then etching efficiency is improved, but silicon nitride region is unintentionally etched
Solution Approach 1:
A protective film is formed on the silicon nitride region before the etching process begins. This preliminary protective layer prevents the silicon nitride from being etched during the plasma etching of silicon oxide, thereby maintaining both high etching efficiency and selectivity.
Solution Approach 2:
The protective film acts as an intermediary layer between the plasma etching process and the silicon nitride region. It allows the etching to proceed efficiently on silicon oxide while blocking the harmful etching effects from reaching the silicon nitride, thus resolving the contradiction between efficiency and selectivity.
2Manufacturing precision
If protective film is formed on silicon nitride before etching, then selectivity is improved, but process complexity increases
Solution Approach 1:
The protective film is formed using the same plasma processing equipment and fluorocarbon-based gas that will be used for the etching process. This self-service approach allows the protective layer to be created in-situ without requiring separate deposition equipment or additional material layers, thereby maintaining selectivity while minimizing process complexity.
Solution Approach 2:
The fluorocarbon-based plasma process serves dual functions: it first forms the protective film on silicon nitride, and then performs the etching of silicon oxide. This multi-functionality eliminates the need for separate protective layer deposition steps, reducing overall process complexity while maintaining high selectivity.
3Manufacturing precision
If multiple etching sequences are used to control etching amount, then manufacturing precision is improved, but processing time increases
Solution Approach 1:
The protective film is formed in advance before the etching sequences begin. This preliminary protective layer remains in place throughout the multiple etching sequences, allowing precise control of etching amounts without requiring additional protective steps between sequences, thereby maintaining manufacturing precision while minimizing processing time.
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 method effectively suppresses the etching of silicon nitride while efficiently etching silicon oxide, enabling the formation of precise openings by controlling the etching sequences and deposit formation, thus improving the manufacturing process for electronic devices.
Implementation Method 1
a first step of generating a plasma of a processing gas containing a fluorocarbon gas in a processing chamber where the target object is accommodated and forming a deposit containing fluorocarbon on the target object
Implementation Method 2
a first step of generating a plasma of a processing gas containing a fluorocarbon gas in a processing chamber where the target object is accommodated
Implementation Method 3
a second step of etching the first region by radicals of fluorocarbon contained in the deposit
Data Source
AI summary
An etching method is provided for selectively etching a first region of silicon oxide with respect to a second region of silicon nitride. The target object includes the second region, the first region and a mask. The etching method includes a first sequence and a second sequence. Each of sequence includes, a first step of generating a plasma of a processing gas containing a fluorocarbon gas in a processing chamber where the target object is accommodated and forming a deposit containing fluorocarbon on the target object, and a second step of etching the first region by radicals of fluorocarbon contained in the deposit. The first sequence is performed during a period including time when the second region is exposed, and an etching amount of the first region in the first sequence is smaller than an etching amount of the first region in the second sequence.