Oxide Semiconductor Plasma Etching With High Mask Selectivity
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Solution Overview
Problem
Existing methods for etching oxide semiconductor films, such as those containing indium, gallium, and zinc, face challenges in achieving a high mask selection ratio and vertical etching shape, particularly when using silicon oxide films as hard masks, as not all halogen-containing gases effectively differentiate between the oxide semiconductor and silicon oxide films during plasma etching.
Innovation Solution
The method involves using a plasma processing apparatus with a bromine-containing or iodine-containing gas to etch the oxide semiconductor film, generating plasma that selectively etches the film while maintaining a vertical shape, and optionally adding oxygen or carbon monoxide to control the etching process and prevent constricted side walls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chlorine-containing gas is used for etching oxide semiconductor film, then etching can be performed, but mask selection ratio is insufficient and vertical shape cannot be achieved
Solution Approach 1:
The patent changes the chemical composition parameter of the etching gas from chlorine-containing gas to bromine-containing gas (e.g., HBr). This parameter change fundamentally alters the etching chemistry, enabling selective removal of oxide semiconductor material while preserving the silicon oxide mask, thereby achieving both high mask selection ratio and vertical etching shape
Solution Approach 2:
The bromine-containing gas acts as an intermediary substance that facilitates selective etching. The bromine radicals generated from HBr plasma selectively react with indium gallium zinc oxide while having minimal effect on silicon oxide, serving as a chemical mediator that enables discrimination between the two materials for precise pattern transfer
2Productivity
If fluorine-containing gas is used for etching, then oxide semiconductor film can be etched, but silicon oxide mask is also etched
Solution Approach 1:
The patent changes the halogen element parameter from fluorine to bromine in the etching gas composition. Bromine-containing gases provide sufficiently high etching rates for oxide semiconductor films while simultaneously offering selective chemistry that spares silicon oxide masks, thus maintaining both productivity and mask integrity
Solution Approach 2:
The etching process exhibits local quality through material-specific selectivity. The bromine-containing plasma creates different etching rates for different materials: high etching rate for indium gallium zinc oxide regions, and minimal etching rate for silicon oxide mask regions. This spatially differentiated etching behavior enables precise pattern transfer without mask degradation
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 the mask selection ratio, ensuring a vertical etching shape and improving the etching performance by using bromine-containing gases, which outperform chlorine-containing gases in maintaining the desired etching characteristics, and allows for precise control of the etching process.
Implementation Method 1
a step of etching the oxide semiconductor film by plasma generated from the processing gas
Implementation Method 2
etching an oxide semiconductor film with plasma of a processing gas containing a bromine (Br)-containing gas or an iodine (I)-containing gas
Data Source
AI summary
A method for etching an oxide semiconductor film includes: providing a substrate including a mask of a silicon-containing film on an oxide semiconductor film containing at least indium (In), gallium (Ga), and zinc (Zn); supplying a processing gas containing a bromine (Br)-containing gas or an iodine (I)-containing gas; and etching the oxide semiconductor film by plasma generated from the processing gas.