Dielectric Exhaust Pipe Layout for Stable Plasma Cleaning
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Solution Overview
Problem
Existing exhaust pipe systems in film forming apparatuses, such as CVD apparatuses, face challenges in effectively cleaning deposits near the vacuum pump due to insufficient cleaning performance by remote plasma source apparatuses, leading to blockages and vacuum pump overload, and unstable plasma generation due to potential abnormal electric discharges.
Innovation Solution
An exhaust pipe device with a dielectric inner pipe and a radio-frequency electrode on its outer periphery, where the ground electrode is positioned closer on the inner side than the outer side to prevent arcing, generating capacitively coupled plasma for efficient cleaning without disrupting the vacuum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between the radio-frequency electrode and ground electrodes is increased to avoid abnormal electric discharge, then arcing is prevented, but plasma generation becomes unstable
Solution Approach 1:
The ground electrode is configured with non-uniform distance from the radio-frequency electrode along the dielectric pipe: closer on the inner side (facing the pipe interior) and farther on the outer side. This local quality variation allows the inner region to maintain stable plasma generation while the outer region prevents arcing to the pipe exterior.
Solution Approach 2:
The ground electrode structure intentionally breaks symmetry by positioning itself asymmetrically relative to the radio-frequency electrode, with different distances on opposite sides. This asymmetric configuration optimizes plasma stability on the interior side while preventing external arcing.
2Productivity
If a radio-frequency electrode is disposed on the outer periphery of a dielectric pipe with ground electrodes at pipe ends, then plasma can be generated inside the pipe, but abnormal electric discharge such as arcing occurs outside the conduit
Solution Approach 1:
The ground electrode creates a non-uniform electric field distribution with stronger field concentration on the inner side (facing the dielectric pipe interior) and weaker field on the outer side. This local field quality control enables plasma generation inside the pipe while suppressing external arcing.
Solution Approach 2:
The dielectric pipe acts as an intermediary that confines and directs the electric field primarily inside the pipe, while the asymmetrically positioned ground electrode further modulates the field to prevent external discharge.
3Reliability
If the distance between electrodes is increased to prevent arcing, then electric discharge safety improves, but the voltage increase is limited and plasma generation becomes unstable
Solution Approach 1:
The asymmetric ground electrode configuration creates optimal local electric field conditions: sufficient distance on the outer side for discharge prevention, and optimal distance on the inner side for maintaining high plasma generation power with stable capacitively coupled plasma.
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 effectively removes deposits inside the exhaust pipe near the vacuum pump, enhances cleaning performance, and stabilizes plasma generation, preventing abnormal electric discharges and maintaining efficient vacuum operation.
Implementation Method 1
a plasma generation circuit configured to generate plasma inside the dielectric pipe
Implementation Method 2
a dielectric pipe through which gas inside the film forming chamber is exhausted
Data Source
AI summary
An exhaust pipe device according to an embodiment includes a dielectric pipe; a radio-frequency electrode; a ground electrode; and a plasma generation circuit. The radio-frequency electrode is disposed on an outer periphery side of the dielectric pipe and a radio-frequency voltage is applied to the radio-frequency electrode. The ground electrode is disposed on an end portion side of the dielectric pipe such that a distance from the radio-frequency electrode is smaller on an inner side than on an outer side of the dielectric pipe, and a ground potential is applied to the ground electrode. The plasma generation circuit generates plasma inside the dielectric pipe. The exhaust pipe device functions as a part of an exhaust pipe disposed between a film forming chamber and a vacuum pump that exhausts gas inside the film forming chamber.