Plasma Chamber Pumping Duct for Residence Time Tuning
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Solution Overview
Problem
In plasma processing apparatus, varying the residence time of gaseous species in the plasma chamber to enhance the production of chemically active neutral and ionic species, such as radicals, is challenging due to its inverse proportionality to gas flow rate and direct proportionality to pressure, which affects ion beam properties and polymeric species production, making it difficult to independently control without altering other process features.
Innovation Solution
A residence time tuning assembly with a pumping duct connected to the plasma chamber, allowing for separate extraction of gaseous species from the plasma chamber, independent of the extraction aperture, enabling independent control of residence time by adjusting the gas flow rate and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the Z-gap between extraction plate and substrate platen is varied to control residence time, then the vacuum conductance and residence time are adjusted, but the electrostatic field adjacent the extraction aperture changes, affecting ion beam characteristics
Solution Approach 1:
The system is segmented into independent control paths: the pumping duct controls gas flow and residence time, while the extraction aperture maintains stable ion beam extraction. This segmentation eliminates the coupling between residence time control and ion beam characteristics.
Solution Approach 2:
The gas pumping function is extracted from the ion extraction path and implemented through a separate pumping duct. This allows residence time to be controlled independently of the electrostatic field and ion beam characteristics.
2Reliability
If the extraction voltage is adjusted to compensate for electrostatic field changes, then the ion beam extraction is maintained, but the ion energy changes, affecting processing quality
Solution Approach 1:
The gas flow control function is extracted and implemented through the pumping duct, separating it from the ion extraction function. This eliminates the need for extraction voltage adjustments to compensate for field changes, thereby maintaining stable ion energy.
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 solution allows for precise tuning of residence time, optimizing the production of radicals and polymeric species, improving ion beam characteristics, such as beam current and uniformity, while maintaining stable gas pressure and reducing pressure fluctuations during substrate processing.
Implementation Method 1
a pumping duct, connected to the plasma chamber on a first end, and defining a pumping path for extracting a gaseous species directly from the plasma chamber, separately from the extraction aperture
Implementation Method 2
plasma in the ion source may be generated in various ways such as rf excitation, dc, or microwave
Implementation Method 3
In order to generate more chemically active neutral and ionic species (known as radicals), increasing residence time of gaseous species in the plasma chamber is needed
Data Source
AI summary
A plasma processing apparatus. The plasma processing apparatus may include a plasma chamber, to define a plasma therein, and an extraction aperture, arranged along a first side of the plasma chamber, the extraction aperture to define an ion beam extracted therethrough. The plasma processing apparatus may further include a residence time tuning assembly, coupled to a portion of the plasma chamber, different from the first side, wherein the residence time tuning assembly comprises a pumping duct, connected to the plasma chamber on a first end, and defining a pumping path for extracting a gaseous species directly from the plasma chamber, separately from the extraction aperture.