Plasma Etching Gas Mixture Prevents Mask Collapse
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Solution Overview
Problem
The plasma etching process for semiconductor manufacturing faces challenges with mask collapse when forming holes with high aspect ratios in silicon oxide and glass-based films, particularly when a silicon nitride film is interposed, leading to reduced yield and increased manufacturing costs due to the use of expensive Xe gas.
Innovation Solution
The method employs a gaseous mixture of C4F6 and C3F8 gases during plasma etching, with a flow rate ratio of C3F8 to C4F6 between 3/8 to 5/8, to prevent mask collapse without using Xe gas, even for holes with aspect ratios greater than 10, and includes a silicon nitride film between the silicon oxide and glass-based films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gaseous mixture of C4F6 gas, Ar gas, and O2 gas is used for plasma etching of glass based film, then the etching process can be performed, but mask collapse occurs when aspect ratio is increased, reducing production yield
Solution Approach 1:
The invention changes the chemical composition parameters of the processing gas by replacing Ar gas with C3F8 gas in the gas mixture. This parameter change modifies the plasma chemistry to reduce mask collapse while maintaining etching capability, thereby improving production yield for high aspect ratio holes without increasing manufacturing costs
2Object-affected harmful factors
If Xe gas is used to replace Ar gas in the gas mixture, then mask collapse can be prevented, but manufacturing costs increase
Solution Approach 1:
The invention substitutes the expensive Xe gas with a mixture of cheaper C4F6 gas and C3F8 gas. This replacement maintains the functional benefit of preventing mask collapse while significantly reducing the cost of consumable gases, thereby lowering manufacturing costs for semiconductor devices
3Manufacturing precision
If holes with high aspect ratio are formed in silicon oxide film and glass based film, then micro-processing accuracy is achieved, but mask collapse frequency increases
Solution Approach 1:
The invention uses a composite gas mixture of C4F6 and C3F8 instead of a single gas. This composite approach combines the benefits of both gases to achieve plasma chemistry that supports high aspect ratio etching while minimizing mask collapse, thus maintaining both manufacturing precision and reliability
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 effectively restricts mask collapse and improves production yield without increasing manufacturing costs, maintaining the integrity of the resist mask and ensuring accurate plasma etching.
Implementation Method 1
a gaseous mixture containing C4F6 gas and C3F8 gas as a processing gas is used in the plasma etching of the glass based layer
Implementation Method 2
plasma etching a glass based film positioned under the silicon oxide film
Data Source
AI summary
A plasma etching method includes: plasma etching a silicon oxide film to be etched that is positioned under a multi-layer resist mask by using the multi-layer resist mask formed on a substrate to be processed; and plasma etching a glass based film positioned under the silicon oxide film by using the multi-layer resist mask. In the method a gaseous mixture of C4F6 gas and C3F8 gas as a processing gas is used in the plasma etching of the glass based layer.