Plasma Bias Pulse Timing for Stable Ion Attraction During RF Startup
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Solution Overview
Problem
Existing plasma processing technologies face challenges in efficiently generating and stabilizing plasma conditions for effective ion attraction onto substrates, particularly in the initial stages of plasma generation.
Innovation Solution
A plasma processing apparatus that includes a radio frequency power supply to generate source radio frequency power in a first partial period and a bias power supply to provide a pulse of electric bias in the same period, followed by stopping the bias supply during a subsequent period, optimizing the plasma sheath thickness and coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a bias radio frequency power is supplied continuously to attract ions into the substrate, then ion attraction efficiency is improved, but plasma generation stability deteriorates during the initial stages
Solution Approach 1:
The continuous bias radio frequency power supply is segmented into distinct operational phases: a first period where both source and bias powers are supplied together, and a second period where only source power is supplied. This segmentation allows the system to achieve both plasma generation stability during the first period and ion attraction efficiency during the second period, resolving the contradiction between stability and productivity.
Solution Approach 2:
The bias radio frequency power is supplied periodically rather than continuously - it is activated during the first period to stabilize plasma generation, then deactivated during the second period to allow efficient ion attraction. This periodic action pattern enables the system to alternate between stability-focused and productivity-focused operational modes, resolving the technical contradiction.
2Stability of the object's composition
If the rise time of source radio frequency power is extended to stabilize plasma generation, then plasma generation stability is improved, but processing time increases
Solution Approach 1:
The source radio frequency power is supplied at a higher level during the first period before the actual processing begins, performing a preliminary plasma generation action that stabilizes the plasma environment in advance. This preliminary action reduces the rise time needed during the subsequent second period, thereby resolving the contradiction between stability and processing time.
Solution Approach 2:
The system dynamically adjusts the source radio frequency power levels between two distinct periods - a higher power level during the first period for rapid plasma generation and stability, then transitions to the processing phase in the second period. This dynamic power adjustment enables fast plasma generation without compromising stability, resolving the time-stability contradiction.
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 enhances plasma generation stability and reduces the time to achieve a steady-state plasma condition, improving ion attraction efficiency and process control.
Implementation Method 1
a radio frequency power supply electrically coupled to the chamber and configured to generate source radio frequency power to generate plasma in the chamber
Implementation Method 2
a bias power supply electrically coupled to the substrate support and configured to generate an electric bias to attract ions into the substrate support
Data Source
AI summary
A plasma processing apparatus discloses herein may include a chamber, substrate support, a radio frequency power supply, and a bias power supply. The substrate support is disposed in the chamber. The radio frequency power supply is configured to supply the source radio frequency power in a first partial period including a rise time of the source radio frequency power and a second partial period subsequent to the first partial period. The bias power supply is configured to supply a pulse of the electric bias to the substrate support in the first partial period, and stop supply of the electric bias from an end time of supply of the pulse of the electric bias to at least a time point between a start time point and an end time point of the second partial period.