Plasma Processing Apparatus RF Power Diversion Control
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Solution Overview
Problem
In plasma processing of semiconductor wafers, the diversion of first radio frequency power into the output line of the second radio frequency power supply via plasma leads to unstable impedance matching, resulting in variations in the processing result due to reflected power, affecting reproducibility and plasma stability.
Innovation Solution
A plasma processing apparatus with a control device that adjusts the first radio frequency power supply to prevent power diversion by setting the second matching device to a predetermined value or disconnecting the second transmission path, ensuring stable impedance matching and plasma stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first radio frequency power supply supplies power to the first electrode, then plasma processing is enabled, but the power is diverted into the second radio frequency power supply output line via plasma causing instability
Solution Approach 1:
The patent extracts and removes the harmful diverted power from the system by providing a dedicated discharge path through the third resistor connected to ground. This prevents the diverted power from affecting the second radio frequency power supply and its impedance matching, thereby eliminating the source of instability while maintaining the benefits of dual electrode plasma processing.
2Loss of energy
If the second impedance matching device performs impedance matching, then power supply efficiency is improved, but the matching becomes unstable when diverted power is large
Solution Approach 1:
The third resistor acts as an intermediary element that provides a controlled discharge path for the diverted power. By introducing this intermediate component between the first electrode and ground, the patent prevents the diverted power from reaching the second impedance matching device, thereby stabilizing the matching operation while still allowing the first electrode to function properly.
3Manufacturing precision
If both first and second radio frequency power supplies are used, then processing precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the power supply system into three independent parts: the first radio frequency power supply for the first electrode, the second radio frequency power supply for the second electrode, and the third resistor providing a dedicated discharge path. This segmentation isolates the functions of each component, allowing the dual power supply system to achieve improved processing precision without proportionally increasing overall system complexity.
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 prevents variations in the processing result by maintaining stable impedance matching and plasma stability, enhancing the reproducibility of the plasma processing and reducing etching rate variations.
Implementation Method 1
the first radio frequency power supplied to the first electrode is diverted into the output line of the second radio frequency power supply via the plasma
Implementation Method 2
the diverted power is reflected by the second radio frequency power supply
Data Source
AI summary
At a time of a wafer processing by a plasma processing apparatus, in order to prevent first radio frequency power from being diverted into an output line of a second radio frequency power supply via plasma, the plasma processing apparatus includes: a processing chamber in which a sample is plasma-processed; a sample stage that includes a first electrode and a second electrode disposed outside the first electrode and on which the sample is placed; a first radio frequency power supply configured to supply first radio frequency power to the first electrode via a first matching device and a first transmission path; and a second radio frequency power supply configured to supply second radio frequency power to the second electrode via a second matching device and a second transmission path. The plasma processing apparatus further includes a control device configured to control the first radio frequency power supply to supply the first radio frequency power to the sample stage when a preset value of the second matching device is a predetermined value. The predetermined value is a value that makes an impedance of the second transmission path an impedance at which the radio frequency power is not detected by the second matching device.