Plasma Source Frequency Tuning Across Bias Phases to Cut RF Reflection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing plasma processing apparatuses face challenges in reducing the degree of reflection of source radio frequency power, which affects the efficiency of plasma generation and processing.
Innovation Solution
The apparatus includes a radio frequency power supply that sets the source frequency of the source radio frequency power in each phase period within the waveform cycle to a frequency obtained by adding a shift amount and random noise to the source frequency in the same phase period of the preceding waveform cycle, thereby minimizing reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the source frequency is kept constant in each phase period, then the control system is simple, but the degree of reflection of source radio frequency power increases
Solution Approach 1:
The patent applies dynamics by making the source frequency variable rather than fixed. Specifically, the source frequency in each phase period is dynamically adjusted based on the frequency from the previous waveform cycle plus a random shift amount, allowing the system to adapt to changing plasma conditions and minimize reflection losses while maintaining relatively simple control logic.
Solution Approach 2:
The patent implements feedback by using the source frequency from the previous waveform cycle as a basis for determining the current cycle's frequency. The system feeds back the frequency information across waveform cycles and applies random shifts to continuously optimize the source frequency for minimizing reflection, creating a self-adjusting control mechanism.
2Loss of energy
If the source frequency is frequently adjusted to minimize reflection, then the degree of reflection decreases, but the system stability deteriorates
Solution Approach 1:
The patent applies periodic action by adjusting the source frequency at regular intervals corresponding to waveform cycles rather than continuously. The frequency is modified once per waveform cycle based on feedback from the previous cycle, providing periodic optimization that reduces reflection while maintaining system stability through predictable, rhythmic adjustments rather than chaotic continuous changes.
Solution Approach 2:
The patent implements parameter changes by modifying the source frequency parameter in a controlled manner. Instead of making large or random changes, the system applies small random shifts to the frequency from the previous cycle, allowing gradual adaptation that reduces reflection losses while preventing instability through controlled, incremental parameter modification.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A plasma processing apparatus includes a chamber, a substrate support, a radio frequency power supply and a bias power supply. The substrate support includes a bias electrode and provided inside the chamber. The radio frequency power supply is configured to generate source radio frequency power for plasma generation within the chamber. The bias power supply is configured to periodically supply an electric bias having a waveform cycle to the bias electrode. The radio frequency power supply is configured to set a source frequency of the source radio frequency power in each of a plurality of phase periods within the waveform cycle to a frequency obtained by adding a shift amount for minimizing a degree of reflection of the source radio frequency power and random noise to the source frequency in a same phase period within a preceding waveform cycle.