Plasma Processing Gas Timing Synchronization
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Solution Overview
Problem
In plasma processing for semiconductor device manufacturing, there is a challenge in synchronizing the supply of gases and high-frequency power to ensure that the second gas reaches the processing vessel before power is applied and is fully evacuated, leading to inefficiencies and inaccuracies in processing cycles.
Innovation Solution
A plasma processing method where the controller adjusts the timing of gas supply and high-frequency power application based on flow rates and impedance changes, using pre-defined functions or tables to set delay times and adjust power levels, ensuring precise synchronization of gas and power phases during multiple cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the second high frequency power is supplied to the second electrode at the start time point of the second stage, then the power supply response is fast and efficient, but the second gas has not reached the processing vessel yet causing synchronization error
Solution Approach 1:
The gas supply system starts outputting the second gas before the second high frequency power is supplied to the second electrode. This preliminary action ensures that the second gas reaches the processing vessel in time to be synchronized with the power application, resolving the timing mismatch between gas arrival and power supply.
2Manufacturing precision
If the gas supply system outputs the second gas early to ensure timely arrival, then gas reaches the vessel on time, but the time difference between gas supply start and power application increases
Solution Approach 1:
The controller dynamically adjusts the first time difference (delay time before power application) and second time difference (delay time after power cessation) based on flow rates of the first gas and second gas, and impedance changes in the plasma. This parameter optimization minimizes the overall time difference while maintaining precise synchronization between gas arrival and power application.
3Productivity
If the second high frequency power supply is stopped immediately after the second stage ends, then power supply efficiency is high, but the second gas is still being supplied causing residual plasma issues
Solution Approach 1:
The gas supply system stops outputting the second gas before the second high frequency power supply is stopped. This ensures that the second gas is fully evacuated from the processing vessel before power cessation, preventing residual plasma issues and ensuring complete process termination.
4Measurement precision
If automatic timing adjustment based on flow rates and impedance is implemented, then synchronization accuracy is improved, but system complexity increases
Solution Approach 1:
The controller measures impedance changes in the plasma during the second stage and uses this feedback information to automatically adjust the first and second time differences. This feedback mechanism enables precise timing synchronization while automating the adjustment process, reducing the need for manual calibration and complex mechanical adjustments.
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 reduces the time difference between gas supply and power application, improving the accuracy and efficiency of plasma processing by automatically adjusting timing according to recipe specifications and real-time impedance changes, thereby enhancing processing precision and reducing errors.
Implementation Method 1
The first high frequency power supply is configured to supply a first high frequency power for plasma generation
Implementation Method 2
the second high frequency power supply is configured to supply a second high frequency power for ion attraction
Data Source
AI summary
In a plasma processing method includes a first stage of generating plasma of a first processing gas and a second stage of generating plasma of a second processing gas, are performed, a time difference between a start time point of a time period during which the second stage is performed and a start time point of an output of the second processing gas from a gas supply system is decided automatically according to a recipe. A delay time corresponding to flow rates of the first processing gas and the second processing gas in the second stage is specified from a function or a table.