Plasma Processing RF Power Modulation for Charging Damage
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Solution Overview
Problem
Conventional capacitively coupled plasma processing apparatuses face challenges with charging damage and in-plane uniformity issues due to low ion energy and pressure, leading to non-uniform etching and potential dielectric breakdown, especially with high-frequency RF power usage.
Innovation Solution
A plasma processing apparatus and method that alternately repeats phases of high and low RF power to generate and stop plasma at predetermined intervals, reducing charge accumulation and balancing ion and electron injection, thereby preventing charging damage and improving uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-frequency RF power (40 MHz or greater) is used to achieve low ion energy and low pressure, then etching selectivity and in-plane uniformity are improved, but charging damage occurs due to in-plane non-uniformity of plasma potential
Solution Approach 1:
The patent applies periodic modulation to the RF power supply, switching between high power (plasma generation) and low power (plasma extinction) states. This periodic action prevents charge accumulation by periodically neutralizing charges during the plasma extinction phase, thereby resolving the charging damage issue while maintaining the benefits of high-frequency RF power for etching uniformity
2Manufacturing precision
If low pressure and low ion energy are used to improve etching selectivity, then charging damage occurs due to in-plane non-uniformity of plasma potential
Solution Approach 1:
The periodic modulation of RF power creates alternating phases of plasma generation and extinction. During the extinction phase, accumulated charges are neutralized, preventing dielectric breakdown. This allows the system to operate at low pressure with improved selectivity without suffering from charging damage
3Productivity
If continuous plasma generation is used to maintain processing efficiency, then charge accumulation occurs leading to dielectric breakdown
Solution Approach 1:
The system alternates between high-power plasma generation mode (for efficient processing) and low-power plasma extinction mode (for charge neutralization). This periodic cycling maintains processing efficiency while periodically eliminating charge accumulation that would otherwise lead to dielectric breakdown
Solution Approach 2:
The patent maintains continuous processing effectiveness by rapidly switching between plasma generation and extinction states. The useful action of plasma processing continues through repeated cycles, with the extinction phase serving to reset charge conditions for the next processing cycle
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 effectively reduces charging damage, enhances in-plane uniformity, and improves the reliability and stability of plasma processing by minimizing continuous plasma generation time and balancing charge distribution.
Implementation Method 1
a radio frequency (RF) voltage is applied between the electrodes, and electrons are accelerated by an electric field formed between the electrodes by the application of the RF voltage. Plasma is generated due to ionization by collision between the electrons and the processing gas
Data Source
AI summary
A plasma processing apparatus includes a first radio frequency (RF) power supply unit for applying a first RF power for generating a plasma from a processing gas to at least one of a first and a second electrode which are disposed facing each other in an evacuable processing chamber. The first RF power supply unit is controlled by a control unit so that a first phase at which the first RF power has a first amplitude for generating a plasma and a second phase at which the first RF power has a second amplitude for generating substantially no plasma are alternately repeated at predetermined intervals.