Plasma Supply Unit Ground Shield Cross-Talk
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Solution Overview
Problem
The challenge in substrate processing is achieving uniform plasma supply and consistent thin film quality due to cross-talk between plasma currents flowing through RF rods, leading to non-uniform plasma density and film quality, especially at higher frequencies.
Innovation Solution
A substrate processing apparatus is designed with a plasma supply unit that includes a ground shield between conductive portions to prevent cross-talk, using a high-frequency plasma generator equal to or greater than 60 MHz, and a configuration of RF rods and feeds to ensure uniform plasma application, including a bridge and split points to connect the RF rods to the gas supply unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple RF rods are used to supply plasma power, then plasma uniformity is improved, but cross-talk between plasma currents causes non-uniform plasma density
Solution Approach 1:
A ground shield is introduced as an intermediary component between overlapping RF rods to prevent electromagnetic interference. The ground shield acts as a mediator that blocks the harmful cross-talk between adjacent RF rods while allowing the beneficial plasma-generating fields to reach the substrate, thus maintaining plasma uniformity without the detrimental effects of current interference.
Solution Approach 2:
The harmful electromagnetic interference is extracted and directed away from the plasma generation zone by using the ground shield to channel induced currents to ground. This separates the useful plasma-generating function from the harmful interference, allowing multiple RF rods to operate without mutual interference.
2Manufacturing precision
If high frequency plasma (≥60 MHz) is used, then thin film quality is improved, but cross-talk effects are amplified causing non-constant film quality
Solution Approach 1:
The ground shield serves as a frequency-independent intermediary that effectively blocks high-frequency electromagnetic interference. Even at plasma frequencies of 60 MHz or higher where cross-talk is amplified, the ground shield maintains electrical isolation between RF rods, preventing the amplification of harmful effects while preserving the quality benefits of high-frequency plasma.
3Manufacturing precision
If RF rods are positioned to overlap for uniform plasma distribution, then plasma coverage is improved, but electromagnetic interference increases
Solution Approach 1:
The ground shield is strategically positioned between overlapping RF rod structures to provide electromagnetic isolation. This allows the RF rods to maintain their overlapping configuration for uniform plasma distribution while the ground shield blocks the electromagnetic interference that would otherwise result from such close positioning.
4Area of stationary object
If plasma conductors are placed close together, then reaction space coverage is improved, but induced signal components increase
Solution Approach 1:
The ground shield acts as an intermediary barrier between closely spaced plasma conductors, allowing them to be positioned close together for maximum reaction space coverage while preventing the generation of harmful induced signal components. The shield provides electrical isolation that eliminates mutual inductance effects between adjacent conductors.
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 configuration enhances the uniformity of plasma supply and thin film quality by reducing cross-talk and ensuring consistent plasma power distribution, improving the uniformity of the RF electric field and film quality even at higher frequencies.
Implementation Method 1
a ground shield located between the first conductive portion and the second conductive portion
Implementation Method 2
a plasma process such as plasma-enhanced atomic layer deposition (PEALD) has been suggested
Implementation Method 3
using high frequency plasma equal to or greater than 60 MHz
Data Source
AI summary
A plasma supply unit includes a first conductive portion, a second conductive portion having at least a part extending to overlap the first conductive portion, and a ground shield located between the first conductive portion and the second conductive portion, and a substrate processing apparatus including the plasma supply unit.