Nanosecond Pulser Circuit for Plasma Voltage Droop Compensation
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Solution Overview
Problem
Existing plasma systems experience voltage droop between consecutive high voltage pulses due to ion current, leading to voltage reduction on wafers within the plasma chamber.
Innovation Solution
A nanosecond pulser system with a snubber circuit and droop compensation mechanism, including a snubber resistor and capacitor, is used to counteract ion current, maintaining a substantially flat voltage between pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high voltage pulses are applied to the plasma chamber, then plasma generation and processing capability are improved, but voltage droop occurs between consecutive pulses due to ion current
Solution Approach 1:
The patent applies preliminary anti-action by introducing a compensating voltage signal before the voltage droop becomes problematic. The system measures the actual voltage between pulses and generates a compensating signal that counteracts the expected ion current effect, thereby pre-correcting the voltage deviation before it affects plasma processing quality
Solution Approach 2:
The patent implements feedback control by continuously measuring the voltage between consecutive high voltage pulses using a voltage divider circuit. The measured voltage is compared with a reference voltage, and the difference is amplified and fed back to adjust the output voltage, thereby automatically compensating for voltage droop caused by ion current
2Adaptability or versatility
If ion current is present in the plasma chamber, then plasma processing function is enabled, but voltage reduction on the wafer occurs between pulses
Solution Approach 1:
The system uses feedback control to monitor the actual voltage between pulses and automatically adjusts the output to maintain consistent wafer voltage. The voltage divider circuit measures the voltage, the amplifier compares it with the reference, and the system corrects any deviation, ensuring reliable and consistent voltage delivery to the wafer despite ion current effects
Solution Approach 2:
The patent replaces direct mechanical/voltage control with an electronic feedback control system. Instead of relying on precise mechanical timing and fixed voltage output, the system uses electronic sensing, amplification, and feedback adjustment to dynamically compensate for ion current effects, achieving more reliable voltage consistency
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 system maintains a consistent voltage across the wafer by offsetting the voltage reduction caused by ion current, ensuring stable plasma processing.
Implementation Method 1
a snubber circuit coupled with the one or more switches
Implementation Method 2
a transformer coupled with the one or more solid state switches
Implementation Method 3
One that produces high frequency waveforms that can be used to create a plasma within the plasma chamber
Data Source
AI summary
A pulse generator is disclosed. The pulse generator includes a DC source; a plurality of switches, a transformer; and a pulsing output. The pulse generator can be coupled with a plasma chamber. The pulsing output outputs high voltage pulses having a peak-to-peak voltage greater than 1 kV and a voltage portion between consecutive high voltage bipolar pulses that has a negative slope that substantially offsets the voltage reduction on a wafer within a plasma chamber due to an ion current. The resulting voltage at the wafer may be substantially flat between consecutive pulses.