Pulsed Biasing for Ion Source Electrode Cleaning
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Solution Overview
Problem
The accumulation of materials on the inner walls of the ion source chamber and electrodes in ion implantation systems reduces ion generation rates and beam current, necessitating frequent and time-consuming maintenance, which decreases IC production time and increases manufacturing costs.
Innovation Solution
The ion source operates in both processing and cleaning modes, where the ion beam is defocused to strike the electrodes, and pulsed biasing is applied to the ion source chamber and electrodes during the cleaning mode to remove material buildup without disrupting the system's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the ion source is operated continuously to maintain IC production, then productivity is improved, but material accumulation on electrodes reduces ion generation rate and beam current
Solution Approach 1:
The patent applies periodic pulsed biasing to the extraction electrode assembly during ion source operation. The bias voltage is applied in pulses rather than continuously, creating periodic cleaning action that removes material accumulation from electrode surfaces and apertures. This periodic maintenance action occurs during normal operation without requiring system shutdown, thus maintaining productivity while preventing degradation of ion generation rate and beam current.
2Reliability
If manual cleaning is performed to remove material accumulation, then ion source performance is restored, but the system must be powered down and vacuum released, causing loss of time
Solution Approach 1:
The patent implements a self-service cleaning mechanism where the extraction electrode assembly cleans itself through pulsed biasing during normal ion source operation. The ion source maintains its own performance without requiring external manual intervention, system shutdown, or vacuum release. The pulsed biasing automatically removes material accumulation, eliminating the time loss associated with traditional manual cleaning procedures.
Solution Approach 2:
The cleaning function is integrated into the continuous operation of the ion source. The pulsed biasing applies cleaning action during normal operation without interrupting the ion beam generation or requiring system shutdown. This maintains continuous useful action for both ion production and electrode cleaning, eliminating downtime and maintaining vacuum conditions throughout the process.
3Duration of action of stationary object
If frequent maintenance is performed to extend ion source lifetime, then reliability is improved, but productivity decreases due to system shutdown and vacuum release
Solution Approach 1:
The patent employs periodic pulsed biasing that continuously removes material accumulation from electrode surfaces during operation. This periodic self-cleaning action prevents the degradation that would otherwise require frequent maintenance shutdowns. By maintaining electrode cleanliness continuously, the ion source lifetime is extended without requiring frequent interruptions to IC production, thus improving both durability and productivity simultaneously.
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 method extends the lifetime of the ion source and improves performance by reducing maintenance time and costs, allowing continuous IC production without powering down the ion implanter system.
Implementation Method 1
the ion beam is defocused so that it strikes the suppression electrode and the ground electrode
Implementation Method 2
the defocused ion beam removes material from the suppression electrode
Implementation Method 3
a plasma is created in an ion source chamber. This plasma contains positively charged dopant ions
Implementation Method 4
a plasma is created in an ion source chamber. This plasma contains positively charged dopant ions
Implementation Method 5
one or more of the electrodes may be negatively biased to attract the positively charged dopant ions through an extraction aperture
Data Source
AI summary
A system and method of improving the performance and extending the lifetime of an ion source is disclosed. The ion source includes an ion source chamber, a suppression electrode and a ground electrode. In the processing mode, the ion source chamber may be biased to a first positive voltage, while the suppression electrode is biased to a negative voltage to attract positive ions from within the chamber through an aperture and toward the workpiece. In the cleaning mode, the ion beam is defocused so that it strikes the suppression electrode and the ground electrode. The voltages applied to the ion source chamber and the electrodes are pulsed to minimize the possibility of glitches during this cleaning mode.