Plasma Cleaning
This procedure is used to clean surfaces and enhance attachment of PDMS to glass or PDMS to PDMS.
1. Clean all substrate surfaces with Scotch tape.
2. Place PDMS mold (feature side facing up) on a microscope slide. Transfer PDMS on slide into the plasma cleaner.
3. Put another microscope slide (to be attached to the feature face of PDMS mold) in the plasma cleaner.
4. Close the door to plasma cleaner, and close the valve (turn knob inward) on door to isolate inside from outside air. Set power level to medium.
5. Create vacuum by turning on pump. Watch needle on vacuum gage moving counterclockwise past the 200 mark.
6. Turn on power, slowly open valve (turn knob outward) until a purplish glow is observed.
7. Let the purplish glow persist for 25 seconds, then turn power off.
8. Open valve completely to let air in. Close valve to reestablish vacuum. Turn off pump when the needle on vacuum gage returns to its position around the 200 mark (this step is important in removing toxic gas generated in the plasma cleaner).
9. Open valve to let air in. Open door when atmospheric pressure is reached.
10. Remove PDMS mold on microscope slide and the other microscope slide.
11. Attach the empty microscope slide (the side facing up when placed in plasma cleaner) to the PDMS mold (feature, the side facing up) and squeeze for 30 seconds.
12. Remove the microscope slide lying underneath the PDMS mold (contacting the non-feature side). The PDMS mold should now be only attached to the originally empty microscope slide, with feature facing down to the slide.
From the manufacturer
http://www.harrickplasma.com/products_operation.php
PLASMA PRODUCTS:
Details of Operation
Note: A detailed User's Manual is provided with all Harrick Plasma's Plasma Cleaner models.
Principles of Operation
The sample is placed in the plasma vacuum chamber
Process gas(es) are admitted to the chamber at low flow rates (1-2 SCFH) using either a needle valve or the PlasmaFlo accessory and are kept at low pressure (~200-600 mTorr) through vacuum pumping
The gases are subject to induced RF magnetic and electric fields generated by a solenoidal coil current
Plasma is generated through the subsequent RF/collisional heating of the electrons in the gas
Details of Operation
The plasma vacuum chamber door has an o-ring quick disconnect seal for easy access to the chamber
The vacuum pump is connected to an outlet at the back of the reaction chamber
The needle valve is used to bleed in process gas and control the pressure during plasma processing
The RF power level can be adjusted by means of a three-way selector switch
The plasma will emit a characteristic glow, which visibly indicates the successful generation of the plasma state
The temperature change of a substrate during plasma treatment is minimal
The 3-way valve is used to quickly switch from bleeding in gas, isolating the chamber, and venting
Surface Cleaning / Modification
The interaction between the plasma and the surface is determined by:
The nature of the substrate and surface contaminant layers
The process gases used
The pressure and flow rate of the gases
The RF power level & length of sample exposure
For surface cleaning, a few seconds exposure, following pump down of the chamber and formation of plasma, is often adequate
Surface cleanliness can be tested most easily by observing the wettability of the sample: on a clean surface, water drops will not bead, but will spread out in a uniform film
Plasma Generation with Room Air as the Process Gas [+]