UV-Seeded ICP Ignition to Cut Arcing and Dielectric Sputtering
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Solution Overview
Problem
Conventional plasma processing tools face challenges in achieving reliable and efficient ignition of inductively coupled plasmas, particularly at reduced RF power levels and higher gas pressures, which can result in intermittent ignition, arcing, and sputtering of dielectric walls.
Innovation Solution
The use of an ultraviolet light source to emit a UV light beam onto a dielectric wall or metal surface within the plasma chamber, prior to or during plasma ignition, enhances the rate of initial exponential growth of the plasma and reduces the required RF power for ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional plasma ignition methods are used at reduced RF power levels, then energy consumption is reduced, but ignition reliability deteriorates with intermittent ignition and arcing
Solution Approach 1:
The patent applies preliminary action by introducing a UV light source that pre-ionizes the gas before RF power is applied. The UV radiation creates initial electron density in the plasma chamber, which serves as a seed for subsequent plasma ignition. This preliminary ionization action enables reliable plasma startup at reduced RF power levels by eliminating the need for high-power ignition pulses that cause arcing and intermittent ignition.
2Quantity of substance
If conventional plasma ignition is attempted at higher gas pressures, then plasma density can be increased, but ignition stability deteriorates with intermittent ignition
Solution Approach 1:
The UV light source performs preliminary ionization of the gas at higher pressures, creating sufficient initial electron density to sustain plasma ignition. This pre-conditioning of the gas allows the system to achieve stable plasma at higher pressures where conventional methods would fail due to insufficient electron multiplication rate.
3Reliability
If higher RF power is used to ensure reliable plasma ignition, then ignition reliability improves, but ion bombardment of dielectric walls increases causing sputtering
Solution Approach 1:
By pre-ionizing the gas with UV radiation before RF power application, the system achieves reliable plasma ignition at lower RF power levels. This eliminates the need for high-power ignition pulses that create excessive ion bombardment and sputtering of dielectric chamber walls, thereby reducing material degradation while maintaining ignition reliability.
4Device complexity
If conventional ignition methods are used, then device complexity remains low, but ignition speed is slow
Solution Approach 1:
The UV light source performs preliminary ionization of the gas, creating initial electron density that accelerates the plasma ignition process. This pre-conditioning step significantly reduces the time required for plasma to reach operational density levels, improving ignition speed from seconds to much faster timescales while adding only a single light source component to the system.
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 improves the reliability and speed of plasma ignition, reduces ion bombardment of the dielectric window, and enhances the cleanliness and longevity of plasma processing apparatus components.
Implementation Method 1
an ultraviolet light source configured to emit an ultraviolet light beam onto a metal surface that faces an interior volume of the plasma chamber
Data Source
AI summary
Plasma processing apparatus and associated methods are provided. In one example, a plasma processing apparatus includes a plasma chamber. The plasma processing apparatus includes a dielectric wall forming at least a portion of the plasma chamber. The plasma processing apparatus includes an inductive coupling element located proximate the dielectric wall. The plasma processing apparatus includes an ultraviolet light source configured to emit an ultraviolet light beam onto a metal surface that faces an interior volume of the plasma chamber. The plasma processing apparatus includes a controller configured to control the ultraviolet light source.