DC Bias Circuit With Reactant Gas Purge for Particle Control
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Solution Overview
Problem
Substrate processing systems using RF plasma face issues with particle contamination due to suspended particles that settle on the substrate after RF excitation is turned off, leading to defects, and existing purge gases like helium and argon are unstable with DC bias voltage, causing luminous discharge and elevated defects.
Innovation Solution
Implementing a DC bias voltage applied before and after RF plasma extinction, using molecular reactant gases like carbon dioxide as post deposition purge gases to stabilize the bias voltage and alter particle trajectories, reducing contamination during substrate movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RF plasma is used to activate chemical reactions for film deposition, then deposition efficiency is improved, but particle contamination occurs when RF excitation is turned off and particles settle on the substrate
Solution Approach 1:
A DC bias voltage is applied in advance before turning off the RF excitation to create an electric field that prevents particle formation and settlement. The DC bias is maintained during the transition period when RF plasma is extinguished, proactively preventing particle contamination before it occurs.
Solution Approach 2:
A DC bias voltage is introduced as an intermediary mechanism between RF plasma extinction and particle settlement prevention. The DC bias voltage acts as a mediating force that maintains particle suspension and prevents contamination during the transition period when RF plasma is turned off.
2Ease of operation
If inert gases like helium and argon are used as post deposition purge gases, then substrate movement is enabled, but DC bias voltage becomes unstable causing luminous discharge and elevated defects
Solution Approach 1:
The type of purge gas is changed from inert gases (helium, argon) to molecular reactant gases (nitrogen, oxygen, carbon dioxide). This parameter change in gas composition eliminates luminous discharge and stabilizes DC bias voltage while still enabling substrate movement during post deposition processing.
Solution Approach 2:
Molecular reactant gases that can support combustion or chemical reactions are used to suppress luminous discharge and stabilize DC bias voltage. The potential reactivity of these gases is converted into a benefit by preventing discharge instability and improving process reliability during substrate movement.
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
Stabilizes the DC bias voltage, effectively reducing substrate defects by preventing particle contamination and enhancing processing efficiency in PECVD/PEALD systems.
Implementation Method 1
A DC bias voltage is supplied to one of the upper electrode and the lower electrode while the post deposition purge gas is delivered by the gas delivery system
Implementation Method 2
An RF generating system is configured to deposit film on the substrate by generating RF plasma in the processing chamber between the upper electrode and the lower electrode
Implementation Method 3
In chemical vapor deposition (CVD) or atomic layer deposition (ALD) processes, a gas mixture including one or more precursors may be introduced into the processing chamber to deposit a film on the substrate
Implementation Method 4
electrostatic repulsion suspends the particles in the RF plasma at a plasma boundary or plasma sheath
Data Source
AI summary
A substrate processing system includes an upper electrode and a lower electrode arranged in a processing chamber. A gas delivery system is configured to selectively deliver at least one of a precursor gas, one or more deposition carrier gases, and a post deposition purge gas. An RF generating system is configured to deposit film on a substrate by generating RF plasma in the processing chamber between the upper electrode and the lower electrode while the precursor gas and the one or more deposition carrier gases are delivered by the gas delivery system. A bias generating circuit is configured to selectively supply a DC bias voltage to one of the upper electrode and the lower electrode while the post deposition purge gas is delivered by the gas delivery system. The post deposition purge gas that is delivered by the gas delivery system includes a reactant gas.