Ion Energy Analyzer Voltage Sweep for Complete Plasma Measurements
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Solution Overview
Problem
Existing plasma processing systems face challenges in accurately measuring ion energy distribution due to limitations in high voltage generating circuits, particularly with descending voltage sweeps, which can result in incomplete ion energy distribution measurements and inefficient battery usage.
Innovation Solution
A method involving a high voltage generating circuit with a switch and resistor configuration that allows for both ascending and descending voltage sweeps, enabling complete ion energy distribution measurements by sampling ion current during both stages and combining the data for a full set of measurements across the ion energy distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a descending voltage sweep is used in the high voltage generating circuit, then power consumption is reduced, but ion energy distribution measurements become incomplete
Solution Approach 1:
The voltage sweep is divided into two separate stages: an ascending voltage sweep stage and a descending voltage sweep stage. Each stage captures a different portion of the ion energy distribution. By segmenting the measurement process into these two phases, the system can obtain complete ion energy distribution data while maintaining the low power consumption advantage of descending sweeps.
Solution Approach 2:
An ascending voltage sweep is performed first to charge the capacitor and establish the initial voltage conditions before the descending sweep begins. This preliminary action ensures that the capacitor is properly charged and the measurement system is ready for the main descending sweep, enabling complete measurement coverage.
2Measurement precision
If a continuous voltage sweep from zero to maximum is used, then complete ion energy distribution measurements are obtained, but battery power is depleted quickly
Solution Approach 1:
The system uses periodic pulsed voltage sweeps instead of continuous voltage application. The high voltage generating circuit operates in discrete pulses, charging the capacitor to the required voltage level only when measurements are needed, then allowing it to discharge. This periodic operation dramatically reduces average power consumption from the battery while maintaining measurement capability.
Solution Approach 2:
The energy-intensive high voltage generation function is extracted from continuous operation and implemented as a separate, independently controlled voltage sweep circuit. This allows the high voltage to be generated only when needed for measurements, rather than continuously, thereby reducing overall power consumption from the battery.
3Productivity
If rapid voltage charging is implemented, then measurement speed is improved, but battery current demand increases
Solution Approach 1:
A capacitor is introduced as an intermediary energy storage element between the battery and the high voltage generating circuit. The capacitor charges rapidly from the battery during short pulses, then discharges to provide the high voltage sweep. This intermediary allows rapid voltage changes for fast measurements while the battery only needs to supply brief, high-current pulses rather than sustained current.
Solution Approach 2:
The voltage charging occurs in periodic pulses rather than continuously. The capacitor is charged rapidly during brief intervals when measurements are performed, then allowed to discharge and rest. This periodic charging pattern enables fast measurement response while keeping the average current demand on the battery manageable.
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 ensures comprehensive ion energy distribution measurements and improves battery performance by reducing power consumption, allowing for longer operation without battery replacement or recharging.
Implementation Method 1
provid a substrate for placement in a plasma processing system and exposure to the plasma
Implementation Method 2
a resistor in parallel with the high voltage switch, sampling ion current during a first stage while a first voltage is being charged on the first grid from the floating ground potential to a plateau voltage
Data Source
Figure 1
Figure 2(a)~2(d)
Figure 3(a)~3(b)
AI summary
An apparatus for obtaining ion energy distribution measurements in a plasma processing system comprising a substrate for placement in the plasma processing system and exposure to the plasma, the substrate having an ion energy analyser disposed therein for measuring the ion energy distribution at the substrate surface during plasma processing, the analyser comprising a plurality of conductive grids, and a collection electrode, C, each grid separated by an insulating layer, a high voltage generating circuit within the substrate and configured to take the output voltage of a battery to power the high voltage generating circuit and apply a voltage to a first grid of the plurality of conductive grids, a high voltage switch configured to discharge the first grid to a floating ground of the apparatus and a resistor in parallel with the high voltage switch, wherein the ion energy analyser is configured to sample ion current during a first stage while a first voltage is being charged on the first grid from the floating ground potential to a plateau voltage and to sample ion current during a second stage while a second voltage applied to the first grid is discharging through the resistor from a predetermined voltage generated by the high voltage generating circuit to the plateau voltage.