Plasma Reactor Electrode Assembly with RF Switching
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Solution Overview
Problem
Conventional plasma reactors face challenges in achieving uniform plasma distribution and repeatability, especially when the workpiece moves through the plasma region, leading to issues like plasma charging damage and metal contamination, due to inadequate RF grounding and inefficient power coupling.
Innovation Solution
The plasma reactor incorporates an intra-chamber electrode assembly with a plurality of filaments surrounded by cylindrical insulating shells, an RF power source, and a system of RF switches to control electrical coupling, allowing for improved plasma uniformity and power coupling efficiency, reducing particle generation and metal contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional plasma reactors use fixed RF grounding and continuous plasma generation, then plasma is continuously produced, but plasma uniformity deteriorates and metal contamination increases
Solution Approach 1:
The patent implements periodic switching of RF power application to different filament groups. The RF power is applied in alternating cycles to first and second groups of filaments, creating periodic plasma generation that prevents continuous metal ion bombardment of the workpiece while maintaining overall plasma uniformity over time.
Solution Approach 2:
The filament array is divided into multiple independently controllable groups (first group and second group). Each group can be selectively activated by RF power through separate RF switches, allowing independent control of plasma generation in different spatial regions and temporal sequences.
2Power
If RF power is continuously applied to generate plasma, then plasma is maintained, but power coupling efficiency decreases and plasma charging damage increases
Solution Approach 1:
RF power is applied periodically in alternating cycles to different filament groups rather than continuously. This periodic application allows the plasma to be maintained while reducing the cumulative ion bombardment energy delivered to the workpiece, thereby reducing plasma charging damage while improving overall power coupling efficiency.
3Reliability
If multiple filaments are used to improve plasma uniformity, then plasma coverage increases, but device complexity increases
Solution Approach 1:
The filament array is segmented into multiple independently controllable groups. Each filament or group of filaments can be independently addressed by RF power through separate RF switches, allowing complex plasma patterns to be generated while maintaining modular control architecture that manages system complexity.
Solution Approach 2:
The same physical filament structure serves multiple functions: it can be individually addressed for localized plasma generation, grouped for regional control, or activated in sequences for temporal modulation. This multi-functionality reduces the need for additional hardware components.
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 plasma uniformity and repeatability, reduces plasma charging damage, and improves throughput by maintaining uniformity across different operating conditions, while also reducing the size of the plasma region and metal contamination.
Implementation Method 1
an RF power source to apply an RF signal the intra-chamber electrode assembly
Implementation Method 2
The generated electric field ionizes the gas atoms, releasing electrons. The electrons in the gas are accelerated by the RF electric field and ionizes the gas directly or indirectly by collisions, producing plasma.
Implementation Method 3
at least one RF switch configured to controllably electrically couple and decouple the first bus from one of i) ground, ii) the RF power source, or iii) the second bus
Data Source
AI summary
A plasma reactor includes a chamber body having an interior space that provides a plasma chamber, a gas distributor, a pump coupled to the plasma chamber, a workpiece support to hold a workpiece, an intra-chamber electrode assembly comprising a plurality of filaments extending laterally through the plasma chamber, each filament including a conductor surrounded by a cylindrical insulating shell, the plurality of filaments including a first multiplicity of filaments and a second multiplicity of filaments arranged in an alternating pattern with the first multiplicity of filaments, a first bus coupled to the first multiplicity of filaments and a second bus coupled to the second multiplicity of filaments, an RF power source to apply RF signal the intra-chamber electrode assembly, and at least one RF switch configured to controllably electrically couple and decouple the first bus from one of i) ground, ii) the RF power source, or iii) the second bus.