Pulsed DC Sputtering Arc Detection via Reverse Current Thresholds
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Solution Overview
Problem
Current methods and apparatus for arc detection during substrate processing fail to detect up to 16% of arcs due to hardware/firmware limitations and short arc durations, leading to underreporting and untreated arc events.
Innovation Solution
The method involves supplying pulsed DC power to a target in a processing chamber and determining the reverse current during the pulse off time. If the reverse current exceeds at least one of two predefined thresholds, a pulsed DC power shutdown response is generated; otherwise, power continues to be supplied.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current, voltage, and/or change of current or voltage sensor data are used during pulse on time for arc detection, then arc detection can be performed during processing, but up to 16% of arcs fail to be detected due to short arc durations or arc current/voltage not meeting thresholds
Solution Approach 1:
The patent inverts the detection approach by measuring reverse current during pulse off time instead of forward current during pulse on time. This allows detection of arcs that do not meet traditional thresholds by detecting the reverse current signature that occurs when an arc extinguishes, thereby improving detection completeness from 87% to 99%
Solution Approach 2:
The patent uses reverse current as an intermediary indicator to detect arc events. Instead of directly detecting the arc during pulse on time, the system detects the reverse current phenomenon that occurs during pulse off time, which serves as a reliable mediator indicating that an arc event has occurred
2Ease of manufacture
If traditional arc detection thresholds are used during pulse on time, then hardware and firmware limitations are worked within, but fast developing arcs with short duration cannot be detected
Solution Approach 1:
The patent employs periodic pulsed DC power supply with distinct pulse on time and pulse off time phases. By performing detection during the pulse off time phase, the system creates periodic detection opportunities that capture fast developing arcs which would otherwise occur too quickly during the pulse on time phase
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 boosts total arc detectability from approximately 87% to about 99% during substrate processing, effectively addressing the underreporting of arc events.
Implementation Method 1
supplying pulsed DC power to a target disposed in a processing volume of a processing chamber
Implementation Method 2
during a pulse off time, determining if a reverse current is equal to or greater than at least one of a first threshold or a second threshold
Implementation Method 3
a sensor configured to measure a reverse current during operation
Implementation Method 4
If the reverse current is equal to or greater than the at least one of the first threshold or second threshold, generate a pulsed DC power shutdown response
Data Source
AI summary
Methods and apparatus for processing a substrate are provided herein. For example, a method for processing a substrate comprises supplying pulsed DC power to a target disposed in a processing volume of a processing chamber for depositing sputter material onto a substrate, during a pulse off time, determining if a reverse current is equal to or greater than at least one of a first threshold or a second threshold different from the first threshold, and if the reverse current is equal to or greater than the at least one of the first threshold or second threshold, generate a pulsed DC power shutdown response, and if the reverse current is not equal to or greater than the at least one of the first threshold or second threshold, continue supplying pulsed DC power to the target.