Zirconium Oxide Plasma Etching Selectivity
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Solution Overview
Problem
Current plasma etching techniques face challenges in achieving sufficient etching selectivity and forming deep, vertical holes and trenches in high-k films, such as silicon oxide and amorphous carbon films, due to inadequate selectivity between the target film and underlying films.
Innovation Solution
A plasma etching method using a gas mixture of boron trichloride, hydrogen bromide, and hydrogen, with optional noble gases like argon or helium, to enhance the etching selectivity of zirconium oxide films over silicon oxide or amorphous carbon films, allowing for improved pattern formation and deep hole creation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional plasma etching techniques are used, then the etching process can be performed, but the etching selectivity of the target film to the underlying film is insufficient
Solution Approach 1:
The invention changes the chemical composition parameters of the etching gas from conventional single-gas or simple mixture formulations to a specific multi-component gas mixture containing BCl3, HBr, H2, and optional noble gases. This parameter change in gas composition enables simultaneous achievement of high etching selectivity (≥1) and improved vertical hole formation capability by optimizing the chemical reactions at the etching interface.
Solution Approach 2:
The invention uses a composite gas mixture system combining multiple etching chemicals (BCl3, HBr), reducing agents (H2), and optional noble gases. This composite approach allows the gas mixture to provide multiple functions simultaneously: BCl3 contributes to etching rate, HBr enhances selectivity, H2 prevents unwanted side reactions, and noble gases optimize plasma characteristics, collectively resolving the selectivity-precision contradiction.
2Manufacturing precision
If the etching selectivity between target film and underlying film is low, then the etching process is simpler, but deep and vertical holes and trenches cannot be formed
Solution Approach 1:
The invention optimizes multiple gas composition parameters simultaneously: BCl3 provides aggressive etching for deep hole formation, HBr enhances selectivity through selective chemical bonding, H2 suppresses polymer formation that would reduce verticality, and noble gases adjust plasma density. This multi-parameter optimization enables both deep vertical hole formation and high etching selectivity to be achieved together.
3Productivity
If conventional gas mixtures are used, then the process is easier to control, but the etching rate and selectivity of zirconium oxide film are insufficient
Solution Approach 1:
The invention employs a composite gas system where BCl3 contributes to high etching rate through efficient Si-Cl bond formation, HBr enhances selectivity via Zr-Br selective bonding, H2 prevents carbon deposition that would reduce etching efficiency, and noble gases optimize plasma generation. This composite approach achieves both high productivity and high reliability 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 achieves high etching selectivity and improved etching rates for zirconium oxide films, enabling the formation of desired patterns and deep, vertical features in target films without etching the underlying films, thus overcoming the limitations of existing techniques.
Implementation Method 1
plasma etching with plasma generated from a first gas. The first gas consists of at least one chloride-containing gas of the group of boron trichloride, tetrachloromethane, chloride and silicon tetrachloride, at least one hydrogen-containing gas of the group of hydrogen bromide, hydrogen and methane, and a noble gas
Implementation Method 2
etching a film by a plasma etching with plasma generated from a gas
Data Source
AI summary
A plasma etching method is performed by forming a desired pattern of a mask into a film including a zirconium oxide film by plasma etching with plasma generated from a first gas. The first gas consists of at least one chloride-containing gas of the group of boron trichloride, tetrachloromethane, chloride and silicon tetrachloride, at least one hydrogen-containing gas of the group of hydrogen bromide, hydrogen and methane, and a noble gas. An underlying film of a silicon oxide film or an amorphous carbon film is provided underneath the zirconium oxide film, and an etching selectivity of the zirconium oxide film to the underlying film is greater than or equal to one.