RF Waveform Shaping in Plasma Processing to Limit Ion Bombardment
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Solution Overview
Problem
Existing plasma processing technologies face challenges in efficiently generating plasma while minimizing ion bombardment on substrates, leading to potential damage during processing.
Innovation Solution
A plasma processing apparatus equipped with a voltage waveform shaping unit that includes a capacitor and a diode or switching element to control the RF power supply's voltage waveform, suppressing positive voltage fluctuations and ion bombardment by storing and redirecting power, thereby concentrating high-density plasma near the upper electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RF power is applied to generate plasma, then plasma generation efficiency is improved, but ion bombardment on substrate increases causing damage
Solution Approach 1:
The patent applies dynamic control of the voltage waveform by adjusting the duty cycle of the RF power supply. By making the voltage application time-variable rather than constant, the system can optimize plasma generation during specific phases while minimizing ion bombardment during other phases, thus resolving the contradiction between plasma efficiency and substrate protection
Solution Approach 2:
The patent employs periodic voltage waveform application with controlled duty cycles (e.g., 10-90% ranges) to alternately enhance plasma generation and reduce ion bombardment. This periodic modulation allows the system to achieve high plasma density during active phases while providing rest phases that reduce cumulative ion damage to the substrate
2Quantity of substance
If positive voltage of RF is increased to enhance plasma, then plasma density is improved, but ion energy and bombardment intensity increase
Solution Approach 1:
The patent changes the voltage waveform parameters by suppressing the positive voltage component and adjusting the duty cycle. This parameter modification allows maintaining adequate plasma density through controlled voltage application while reducing the peak ion energy that would otherwise result from high positive voltage swings, thus decoupling plasma density from 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
The solution enables efficient plasma generation with reduced ion bombardment, enhancing processing efficiency and substrate protection by maintaining stable plasma potential and ion energy control.
Implementation Method 1
a radio frequency power supply to apply RF power to the upper electrode to generate plasma of the processing gas
Implementation Method 2
a voltage waveform shaping unit provided between the RF power supply and the upper electrode to shape a voltage waveform of the RF power supply
Implementation Method 3
connecting a potential adjusting mechanism having a diode to the substrate electrode
Data Source
AI summary
A plasma processing apparatus is provided to perform plasma processing on a substrate. The plasma processing apparatus includes a processing chamber, a substrate support disposed in the processing chamber to place thereon the substrate, a grounded lower electrode provided in the substrate support, an upper electrode disposed to face the lower electrode, a gas supply unit to supply a processing gas to a space between the upper electrode and the substrate support, and a radio frequency power supply to apply RF power to the upper electrode to generate plasma of the processing gas. The plasma processing apparatus further includes a voltage waveform shaping unit provided between the RF power supply and the upper electrode to shape a voltage waveform of the RF power supply to suppress a positive voltage of the RF voltage applied to the upper electrode.