Plasma Bias Phasing for Efficient Negative Ion Delivery
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Solution Overview
Problem
Current plasma processing techniques face inefficiencies in supplying negative ions to substrates due to the faster arrival of electrons, which reduces the electric field intensity for drawing negative ions, limiting the effective delivery of negative ions during plasma processing.
Innovation Solution
A plasma processing apparatus with a chamber, substrate support, plasma generator, and dual power sources is employed, where a first power source generates an electric bias for the lower electrode, and a second power source applies a positive voltage to a member exposed to plasma, controlling the voltage phases to efficiently draw negative ions onto the substrate by neutralizing the electrode potential and reducing electron influx.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single power source is used to generate electric bias for the lower electrode, then the device complexity is reduced, but the ability to efficiently supply negative ions to the substrate is compromised due to electron interference
Solution Approach 1:
The single power source is divided into two separate power sources: a first power source connected to the lower electrode and a second power source connected to the upper electrode. This segmentation allows independent control of electric bias at each electrode, enabling the first power source to generate negative ions while the second power source manages electron interference, thereby improving negative ion supply efficiency without compromising device simplicity
Solution Approach 2:
Instead of using a single power source to generate electric bias for both electrodes, the invention inverts the approach by using two power sources with opposite functions: the first power source generates negative ions at the lower electrode, while the second power source applies positive potential to the upper electrode to repel electrons. This inverted control strategy resolves the contradiction by improving negative ion supply through dual-power-source coordination
2Productivity
If the electric field intensity is increased to draw negative ions faster, then the negative ion delivery efficiency is improved, but electrons arrive even faster and neutralize the electrode potential, reducing the effective electric field
Solution Approach 1:
The second power source is configured to maintain a positive potential at the upper electrode in advance, creating a preemptive counter-action against electron influx. This preliminary anti-action prevents electrons from neutralizing the electric field before negative ions can be effectively delivered, thereby maintaining both high negative ion delivery efficiency and stable electric field conditions
Solution Approach 2:
The second power source establishes a positive potential at the upper electrode before negative ions are supplied, preparing the electric field configuration in advance. This preliminary action ensures that when negative ions are delivered with high intensity, the electric field remains stable and effective by preventing electron interference from the outset
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 ensures efficient supply of negative ions to the substrate by managing the electric bias phases, enhancing the intensity of the electric field for ion delivery and improving the plasma processing efficiency.
Implementation Method 1
The plasma generator 30 is configured to generate plasma from a gas in the chamber 10
Implementation Method 2
The first power source 62 is configured to generate an electric bias EB
Implementation Method 3
The second power source 64 is configured to apply a positive voltage to an upper electrode 30
Data Source
AI summary
A disclosed plasma processing apparatus includes a chamber, a substrate support, a plasma generator, and first and second power sources. The first power source is configured to generate an electric bias and electrically connected to a lower electrode of the substrate support provided in the chamber. The second power source is configured to apply a positive voltage to a member in a first period that is a part of a whole period in which the electric bias output from the first power source to the lower electrode has a potential not less than an average potential of the electric bias within a cycle thereof. The member is disposed to be exposed to plasma generated in the chamber. The first power source is configured to output the electric bias having a positive potential to the lower electrode in a second period after the first period.