Plasma Chamber Bias Synchronization With Pulsed DC Magnetic Fields
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Solution Overview
Problem
Current plasma processing techniques struggle to achieve precise control over plasma properties such as density, electron temperature, radical flux, ion flux, and ion angle and energy distributions, which are crucial for patterning high aspect ratio features at a nanoscale pitch with high yield in volume manufacturing.
Innovation Solution
The method involves generating a plasma in a plasma chamber by flowing a discharge gas and coupling RF source and bias signals to electrodes, while simultaneously generating a pulsed DC magnetic field synchronized with the bias signal to modulate the electron temperature profile of the plasma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma processing techniques are used, then plasma processing can be performed, but precise control over plasma properties (density, electron temperature, radical flux, ion flux, ion angle and energy distributions) cannot be achieved
Solution Approach 1:
The patent applies pulsed magnetic fields that can be dynamically adjusted in strength and timing to control plasma properties. The magnetic field is applied in pulses during specific phases of the plasma processing cycle, allowing dynamic modulation of electron temperature, ion flux, and ion angle without requiring a permanently complex magnetic confinement system. This enables precise control of plasma characteristics on-demand.
Solution Approach 2:
The patent changes physical parameters of the plasma by applying external magnetic fields. Specifically, it modulates electron temperature, plasma density, and ion energy distributions by varying the magnetic field strength and timing parameters. This allows precise control over plasma properties to achieve the desired ion flux characteristics for high aspect ratio etching.
2Manufacturing precision
If high aspect ratio features are patterned at nanoscale pitch, then component density increases, but control over ion flux and ion angle becomes more difficult
Solution Approach 1:
The patent employs periodic pulsed magnetic fields applied during specific phases of the etching process. The magnetic field pulses are synchronized with the RF power cycles to periodically enhance ion confinement and collimation. This periodic action maintains ease of operation while achieving the precise ion flux control needed for high aspect ratio nanoscale patterning.
Solution Approach 2:
The magnetic field is applied in advance during plasma ignition and pre-conditioning phases to establish desired electron temperature and ion flux characteristics before the actual etching begins. This preliminary magnetic field application prepares the plasma for optimal ion delivery to high aspect ratio features, making the subsequent etching process easier to control.
3Productivity
If plasma density is increased to improve etch rate, then productivity increases, but control over electron temperature and ion energy distribution deteriorates
Solution Approach 1:
The patent segments the plasma processing into distinct phases with different magnetic field applications. During high-density plasma phases for high etch rate, magnetic field pulses are applied selectively to specific regions or at specific times to maintain ion energy control. This segmentation allows simultaneous achievement of high productivity and precise ion energy control.
Solution Approach 2:
The magnetic field acts as an intermediary between plasma density and ion energy control. Even when plasma density is increased for high productivity, the magnetic field mediates the relationship by confining electrons and modulating ion acceleration, thereby maintaining control over ion energy distribution and preventing loss of manufacturing precision.
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 allows for a highly collimated ion flux with controlled kinetic energy, enhancing the precision and effectiveness of plasma processing, particularly for high aspect ratio contact etch processes, thereby improving yield and reliability in IC manufacturing.
Implementation Method 1
generating a pulsed DC magnetic field in the plasma chamber, by coupling a magnetizing signal to an electromagnet
Implementation Method 2
coupling a radio frequency (RF) source signal to a first RF electrode, where the coupling ionizes the discharge gas
Implementation Method 3
coupling a bias signal to a second RF electrode, the bias signal being a periodic series of bias pulses
Data Source
AI summary
A method for plasma processing a substrate, where the method includes generating a plasma in a plasma chamber within which the substrate is held during processing, where generating the plasma includes: flowing a discharge gas through the plasma chamber; coupling a radio frequency (RF) source signal to a first RF electrode, where the coupling ionizes the discharge gas; and coupling a bias signal to a second RF electrode, the bias signal being a periodic series of bias pulses, each period having a bias-ON time and a bias-OFF time, where a bias voltage waveform is applied during the bias-ON time; generating a pulsed DC magnetic field in the plasma chamber, by coupling a magnetizing signal to an electromagnet, the magnetizing signal being a periodic series of current pulses; and prior to coupling the magnetizing signal, synchronizing the periodic series of current pulses with the bias signal to flow a DC magnetizing current during the bias-ON time.