Plasma Chamber Voltage Cycling to Suppress Electrode Sputtering
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Solution Overview
Problem
In plasma processing apparatuses, the phenomenon of electrode sputtering occurs when the electrode potential exceeds the container wall potential, leading to reduced process efficiency and the need for frequent cleaning, which decreases productivity.
Innovation Solution
A plasma processing apparatus is designed with a controller that periodically alternates between two voltage states, applying a first voltage value for a partial period of the electrode potential cycle and a second, higher voltage value continuously, to control the collision energy of ions and reduce sputtering, while efficiently cleaning the processing container components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the electrode potential is increased to improve plasma generation efficiency, then plasma processing capability is improved, but electrode sputtering occurs and container components are damaged
Solution Approach 1:
The patent applies periodic reversal of the electrode potential between positive and negative half-cycles. During the positive half-cycle, plasma is generated efficiently; during the negative half-cycle, the reversed potential prevents ion bombardment and sputtering of the container components. This periodic action allows high power operation without cumulative sputtering damage.
Solution Approach 2:
The patent inverts the electrode potential periodically, switching between positive and negative polarity. This inversion ensures that during one half-cycle, plasma generation occurs, while during the other half-cycle, the reversed potential protects the container from sputtering by preventing ion acceleration toward the walls.
2Productivity
If continuous plasma processing is performed to maintain productivity, then processing output is improved, but container components accumulate damage and require frequent cleaning
Solution Approach 1:
By implementing periodic potential reversal, the patent enables continuous processing while preventing cumulative sputtering damage. Each negative half-cycle cleans and protects the container components, allowing the processing to continue indefinitely without frequent maintenance, thus maintaining high productivity while extending component lifespan.
Solution Approach 2:
The patent converts the potentially harmful ion bombardment into a beneficial cleaning effect by utilizing the negative half-cycle of potential reversal. The ion flux during the negative half-cycle removes deposited materials from the container walls, transforming what would be damaging sputtering into a self-cleaning mechanism that maintains processing quality and extends component life.
3Quantity of substance
If high voltage is applied continuously to maintain plasma density, then plasma quality is improved, but energy consumption increases and sputtering damage accumulates
Solution Approach 1:
The patent maintains high plasma density during the positive half-cycle when needed for processing, then reduces voltage stress during the negative half-cycle. This periodic application allows the system to achieve high plasma density when required while reducing cumulative energy consumption and preventing continuous sputtering damage, effectively managing the trade-off between plasma quality and energy use.
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 suppresses sputtering and enhances the cleaning process, improving the productivity and efficiency of plasma processing by controlling the collision energy of ions and extending the lifespan of container components.
Implementation Method 1
a plasma generation source configured to supply plasma into the processing container
Implementation Method 2
a bias power supply configured to supply bias power of a desired waveform to the electrode
Data Source
AI summary
A plasma processing apparatus includes: a processing container; an electrode that places a substrate thereon within the processing container; a plasma generation source that supplies plasma into the processing container; a bias power supply that supplies bias power to the electrode; a part exposed to the plasma in the processing container; a DC power supply that supplies a DC voltage to the part; a controller that executes a process including a first control procedure in which a first state in which the DC voltage has a first voltage value and a second state in which the DC voltage has a second voltage value higher than the first voltage value are periodically repeated, and the first voltage value is applied in a partial period in each cycle of a potential of the electrode, and the second voltage value is applied such that the first state and the second state are continuous.