Bias-Compensated High-Voltage Pulsing for Wafer-Chuck Protection
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Solution Overview
Problem
In plasma deposition systems, high voltage pulses can exceed a certain voltage threshold, potentially damaging wafers by creating excessive forces, and existing technologies struggle to maintain the voltage between the chuck and wafer within safe limits during pulsing and non-pulsing periods.
Innovation Solution
A high voltage power system with a bias compensation circuit, including a blocking diode, DC power supply, and a bias capacitor, is used to manage voltage levels, ensuring the voltage between the wafer and chuck remains near or below the threshold by adjusting the bias compensation during pulsing and non-pulsing phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high voltage pulses are introduced to accelerate ions onto the wafer, then etching quality and trench depth are enhanced, but the voltage may exceed safe thresholds and damage the wafer
Solution Approach 1:
A bias compensation circuit is introduced as an intermediary between the high voltage pulser and the wafer-chuck system. This circuit includes a bias compensation capacitor connected in parallel with the chuck, which actively compensates for voltage fluctuations and prevents the voltage between chuck and wafer from exceeding safe thresholds, thereby enabling high voltage pulsing without wafer damage
Solution Approach 2:
The bias compensation circuit operates with feedback control where the voltage between chuck and wafer is continuously monitored and the bias compensation capacitor is adjusted accordingly. During pulsing phases, the circuit detects voltage excursions and compensates by charging or discharging the bias capacitor to maintain voltage within safe limits, ensuring etching quality without wafer damage
2Productivity
If high voltage pulses are applied to improve plasma processing, then productivity is enhanced, but the voltage control during pulsing and non-pulsing periods becomes difficult
Solution Approach 1:
The bias compensation circuit dynamically adjusts its operation based on the pulser state. During pulsing periods, the bias compensation capacitor charges to counteract voltage rises; during non-pulsing periods, it discharges to maintain proper bias. This dynamic behavior automates voltage control, enhancing productivity while managing complexity through adaptive rather than static control
3Reliability
If the voltage between chuck and wafer is limited to prevent damage, then wafer safety is ensured, but the ability to introduce high voltage pulses for plasma processing is restricted
Solution Approach 1:
The system employs periodic action by synchronizing the bias compensation circuit with the pulser cycles. During each pulsing period, high voltage is applied to enable plasma processing; during non-pulsing periods, the bias compensation circuit actively maintains safe voltage levels. This periodic coordination allows full power pulse capability while ensuring continuous wafer safety through rhythmic compensation
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 effectively limits the voltage between the wafer and chuck to prevent damage, allowing for higher voltage pulses to be introduced safely, enhancing trench depth and etching quality while maintaining operational safety.
Implementation Method 1
The bias compensation circuit can include a blocking diode; and a DC power supply arranged in series with the blocking diode
Implementation Method 2
The high voltage power system includes a bias capacitor arranged across at least the DC power supply
Implementation Method 3
a transformer electrically coupled with the high voltage pulsing power supply
Data Source
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AI summary
A high voltage power system is disclosed. In some embodiments, the high voltage power system includes a high voltage pulsing power supply; a transformer electrically coupled with the high voltage pulsing power supply; an output electrically coupled with the transformer and configured to output high voltage pulses with an amplitude greater than 1 kV and a frequency greater than 1 kHz; and a bias compensation circuit arranged in parallel with the output. In some embodiments, the bias compensation circuit can include a blocking diode; and a DC power supply arranged in series with the blocking diode.