Bias Frequency Detuning for Low Power Etching Stability
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Solution Overview
Problem
Substrate processing systems using rapid alternating processes face instability in bias RF source operation due to low TCP power, resulting in very low bias forward power and operational inefficiencies.
Innovation Solution
Implementing a bias frequency adjustment module that selectively adjusts the bias frequency of the RF source to a detuned frequency, increasing the bias power output by matching impedance and optimizing frequency tuning to achieve a predetermined range of bias forward power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If low TCP power is used in rapid alternating processes, then energy consumption is reduced, but bias forward power becomes very low causing operational instability
Solution Approach 1:
The patent changes the bias frequency parameter from its tuned value to a detuned value, which transforms the impedance matching conditions and increases bias forward power delivery to the substrate without increasing TCP power, thus resolving the contradiction between low energy consumption and operational stability
Solution Approach 2:
The system dynamically adjusts the bias frequency in real-time during the rapid alternating process, transitioning between tuned and detuned states to optimize bias power delivery while maintaining low overall energy consumption, making the system adaptable to varying process conditions
2Productivity
If bias frequency is tuned to impedance matching value, then power transfer efficiency is optimized, but bias forward power remains too low for effective etching
Solution Approach 1:
Instead of tuning the bias frequency to achieve impedance matching (conventional approach), the patent inverts the approach by deliberately detuning the frequency from the impedance matching point, which unexpectedly increases bias forward power delivery and enables effective etching while maintaining low TCP power
3Productivity
If bias power is increased to improve etching performance, then productivity increases, but energy consumption and system complexity increase
Solution Approach 1:
The patent achieves increased etching productivity not by increasing bias power consumption, but by changing the bias frequency parameter to a detuned value, which improves power transfer efficiency and enables effective etching at lower overall power levels, thus resolving the contradiction between productivity and energy consumption
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 stabilizes the bias RF source operation, increasing bias power output and enhancing the efficiency of the rapid alternating process etching cycles.
Implementation Method 1
The tuned frequency corresponds to an impedance matching value. The control module controls the bias frequency adjustment module to adjust the bias frequency to a detuned frequency. The detuned frequency increases the bias power of the bias RF source to a predetermined range.
Implementation Method 2
The RF power excites gas molecules within the processing chamber to generate plasma.
Implementation Method 3
The RF bias power can be used to increase a DC bias (a difference in electrical potential between a surface within the processing chamber and ground) and/or a sheath potential (a potential of the plasma) to increase the energy with which charged particles in the plasma strike the substrate.
Data Source
AI summary
A system for performing a rapid alternating process (RAP) etch includes a bias frequency adjustment module that selectively adjusts a bias frequency of a bias radio frequency (RF) source. The bias RF source provides a bias power to a substrate processing system. A control module determines a tuned frequency of the bias RF source. The tuned frequency corresponds to an impedance matching value. The control module controls the bias frequency adjustment module to adjust the bias frequency to a detuned frequency. The detuned frequency increases the bias power of the bias RF source to a predetermined range.