Medium to large scale plasma cleaning machine is an efficient surface treatment equipment widely used in semiconductor, electronics, aerospace, automotive manufacturing, medical equipment and other fields. It is used to remove organic matter, oxides, particles and other pollutants on the surface of materials, improve the activity and adhesion of material surfaces. The following are common cleaning methods and key points:
1、 Preparation before cleaning
Equipment inspection
Ensure that all components of the plasma cleaning machine, such as the vacuum system, power supply, and gas supply system, are functioning properly.
Check the sealing of the vacuum chamber to avoid air leakage.
Calibrate gas flow meters and pressure sensors to ensure accurate parameters.
Workpiece pre-processing
Select the appropriate cleaning process based on the material of the workpiece (such as metal, ceramic, plastic, etc. requiring different parameters).
Perform preliminary cleaning on the workpiece (such as degreasing and dust removal) to prevent large particle pollutants from entering the vacuum chamber.
Gas selection
Common gases: oxygen (O ₂), argon (Ar), nitrogen (N ₂), hydrogen (H ₂), carbon tetrafluoride (CF ₄), etc.
Mixed gas: According to process requirements, multiple gases (such as O ₂+Ar) can be mixed to enhance the cleaning effect.
2、 Cleaning method
Vacuum plasma cleaning
Steps:
Place the workpiece into the vacuum chamber and close the chamber door.
Start the vacuum pump and pump the chamber to the desired vacuum level (usually 10 ⁻²~10 ⁻⁴ Pa).
Inject cleaning gas, adjust gas flow rate and pressure.
Start the plasma power supply, generate plasma, and bombard and chemically react the surface of the workpiece.
After cleaning, turn off the plasma power, restore the chamber to normal pressure, and remove the workpiece.
Features:
Thoroughly cleaned, suitable for the removal of micron or even nanometer level pollutants.
Accurate control of cleaning parameters such as power, time, and gas flow rate.
Atmospheric pressure plasma cleaning
Steps:
Place the workpiece under the atmospheric pressure plasma spray gun.
Start the plasma generator to generate a plasma jet.
The spray gun scans the surface of the workpiece at a certain speed and distance to complete the cleaning.
Features:
No need for vacuum environment, low equipment cost, suitable for online production.
The cleaning efficiency is high, but the uniformity may be slightly inferior to vacuum plasma cleaning.
Remote plasma cleaning
Steps:
Generate plasma in an independent plasma source.
Transport plasma to the vacuum chamber or workpiece surface through pipelines.
Features:
Prevent plasma from corroding the equipment itself and extend its lifespan.
Suitable for workpieces that are temperature sensitive or susceptible to plasma damage.
3、 Optimization of cleaning parameters
power
High power may cause damage to the surface of the workpiece, while low power may result in insufficient cleaning effect.
It needs to be adjusted according to the material of the workpiece and the type of pollutant (such as metal cleaning power is usually lower than semiconductor cleaning).
Gas flow rate and pressure
The gas flow rate affects the plasma density and cleaning rate.
Excessive pressure may lead to a decrease in plasma uniformity, while insufficient pressure makes it difficult to maintain plasma stability.
cleaning time
Too short a time cannot completely remove pollutants, and too long a time may introduce secondary pollution or damage the workpiece.
The optimal cleaning time needs to be determined through experiments.
temperature
Some processes require controlling the temperature of the workpiece (such as low-temperature plasma cleaning) to avoid thermal damage.
4、 Post cleaning treatment
quality inspection
Use surface analysis techniques such as XPS and SEM to test the cleaning effect.
The detection indicators include surface roughness, chemical composition, cleanliness, etc.
subsequent process
Perform subsequent treatments such as coating, bonding, welding, etc. according to the requirements.
5、 Typical application cases
semiconductor manufacturing
Clean the photoresist residue on the wafer surface to improve the subsequent process yield.
medical device
Clean the surface of the implant, remove organic matter and particles, and improve biocompatibility.
aerospace
Clean the surface of composite materials to enhance coating adhesion.
6、 Precautions
safe operation
Comply with equipment safety regulations to avoid high-voltage electric shock and gas leakage.
Gas recovery
Toxic or corrosive gases (such as CF ₄) need to be recycled to avoid environmental pollution.
Equipment maintenance
Regularly clean the vacuum chamber and plasma generator, and replace vulnerable parts such as electrodes and sealing rings.
The cleaning method of medium and large plasma cleaning machines needs to be combined with specific application scenarios and process requirements, and efficient and safe surface treatment can be achieved by optimizing parameters and selecting appropriate cleaning modes.