Synchronized Multi-Frequency RF Power for Plasma Stability
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Solution Overview
Problem
Existing plasma processing methods face challenges in stabilizing plasma generation, leading to inefficiencies and delays in plasma occurrence, which affects the quality and consistency of semiconductor device manufacturing.
Innovation Solution
A method involving the synchronized output of RF powers with different frequencies and duty ratios, along with a third RF power to a bias electrode, to generate plasma within a plasma chamber, ensuring stable plasma generation by reducing delay and reflective power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single RF power source is used to generate plasma, then the device complexity is low, but the plasma generation stability and speed are insufficient
Solution Approach 1:
The single RF power source is segmented into two independent RF power sources with different frequencies (first RF power and second RF power). Each RF power source operates independently to perform specific functions: the first RF power generates plasma while the second RF power accelerates ions. This segmentation resolves the contradiction by enabling stable plasma generation through coordinated multi-frequency operation without requiring a single overly complex power source.
Solution Approach 2:
The system dynamically switches between different RF power frequencies and duty ratios during the plasma generation process. The first RF power operates at a lower frequency with higher duty ratio for plasma generation, while the second RF power operates at a higher frequency with lower duty ratio for ion acceleration. This dynamic operation enables the system to adapt to different process requirements and achieve both stability and speed.
2Productivity
If plasma generation delay is reduced by optimizing RF power timing, then the productivity increases, but the plasma stability may deteriorate
Solution Approach 1:
The first RF power is activated before the second RF power to pre-establish the plasma environment. By generating plasma first with the lower frequency RF power at a higher duty ratio, the system prepares the necessary plasma density and conditions before introducing the higher frequency RF power for ion acceleration. This preliminary action reduces plasma generation delay while maintaining stability through proper sequencing.
Solution Approach 2:
The system employs periodic pulsing of RF powers with specific duty ratios to balance speed and stability. The first RF power operates with a higher duty ratio to maintain continuous plasma generation, while the second RF power uses a lower duty ratio to provide periodic ion acceleration. This periodic action pattern enables fast plasma generation while preserving stability through rhythmic energy input.
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 enables stable and efficient plasma generation, improving the processing of semiconductor wafers by synchronizing RF power outputs to reduce plasma generation delay and enhance stability, thereby improving semiconductor device manufacturing.
Implementation Method 1
a first RF power generation circuit configured to output a first RF power having a first frequency and a first duty ratio to the RF output circuit, a second RF power generation circuit configured to output a second RF power having a second frequency higher than the first frequency and a second duty ratio smaller than the first duty ratio to the RF output circuit
Implementation Method 2
generating plasma inside the plasma chamber based on the first RF power, the second RF power and an energy output from the bias electrode
Implementation Method 3
outputting a third RF power to a bias electrode inside a plasma chamber, and generating plasma inside the plasma chamber based on the first RF power, the second RF power and an energy output from the bias electrode
Data Source
AI summary
A method of operating a plasma processing device includes outputting a first RF power having a first frequency and a first duty ratio, and outputting a second RF power having a second frequency higher than the first frequency and a second duty ratio smaller than the first duty ratio. The outputting of the first RF power and the outputting of the second RF power are synchronized with each other.