Plasma Ignition Bias Pulsing to Reduce RF Reflected Power
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Solution Overview
Problem
Existing plasma processing apparatuses experience high power of reflected waves during the ignition period, which hampers stable plasma generation and prolongs the time before substrate processing can commence.
Innovation Solution
A plasma processing apparatus that applies a series of bias pulses with negative voltages to the electrode, gradually increasing their absolute values during the ignition period to reduce reflected radio-frequency power waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radio-frequency power is supplied to ignite plasma in the chamber, then plasma generation is initiated, but high power of reflected waves occurs during the ignition period
Solution Approach 1:
A bias pulse is applied to the electrode before radio-frequency power is supplied to ignite the plasma. This preliminary action prepares the electrode surface and reduces the impedance mismatch during plasma ignition, thereby minimizing reflected radio-frequency power and enabling stable plasma generation from the outset
Solution Approach 2:
The bias power supply applies periodic bias pulses to the electrode during the ignition period. These pulsed bias voltages modulate the electrode potential, improving plasma ignition stability and reducing reflected power by creating favorable conditions for plasma formation in a periodic manner
2Productivity
If bias power is applied to the electrode to draw ions into the substrate, then ion bombardment is achieved, but plasma ignition stability is compromised during the ignition period
Solution Approach 1:
The bias pulse is applied in advance before radio-frequency power supply to establish proper electrode potential conditions. This preliminary biasing ensures that when plasma ignition occurs, the electrode is already prepared to draw ions effectively, achieving both ignition stability and ion bombardment efficiency
Solution Approach 2:
The bias power supply dynamically adjusts the bias voltage applied to the electrode based on the plasma ignition state. During the ignition period, the bias voltage is controlled to maintain plasma stability, and after ignition, it transitions to provide effective ion bombardment, thus adapting to different operational phases
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
Stable plasma generation is achieved in a shorter time, reducing the time to start substrate processing by minimizing reflected waves.
Implementation Method 1
The radio-frequency power supply supplies radio-frequency power for generating plasma from a gas in the chamber
Implementation Method 2
The bias power supply provides bias energy to the electrode of the substrate support to draw ions into a substrate
Data Source
AI summary
A plasma processing apparatus disclosed includes a chamber, a substrate support, a radio-frequency power supply, and a bias power supply. The substrate support includes an electrode and is provided in the chamber. The radio-frequency power supply supplies radio-frequency power for generating plasma from a gas in the chamber. The bias power supply is electrically coupled to the electrode of the substrate support. The radio-frequency power supply is configured to supply the radio-frequency power in an ignition period in which the plasma is ignited in the chamber. The bias power supply is configured to sequentially apply a plurality of bias pulses, each of which has a negative voltage, to the electrode of the substrate support, and stepwisely or gradually increase absolute values of voltage levels of the plurality of bias pulses in the ignition period.