This specification defines the proper operation of the PDS 2010 Parylene Deposition System.
PDS2010 Parylene Coater is located at Paul Allen Building Room 155. Access to this utility room is limited to staff and qualified labmembers.
The Labcoter™ 2 (PDS 2010) is the first portable Parylene coater of its kind. It is designed for the occasional Parylene user, and is ideal for experimentation and small production runs.
Parylene is a unique polymer consisting of a linear chain of Benzene rings with two Methylene groups replacing 2 Hydrogen atoms on opposite sides of the Benzene ring serving as coupling links for the polymer. This film has become known for its imperviousness to water transmission which enables device protection from environmental deterioration via encapsulation and also for its electrical characteristics which are useful for micro-electrical circuitry. The source material for the deposited film is a dimer form of the parylene molecule in which two monomers are coupled in parallel by the Methylene ends. The dimer is sublimated in a Vaporizer chamber, broken into monomer molecules in the Pyrolizer furnace and then deposited as long chain polymers on substrates in the deposition chamber.
Parylene has three primary variations—C, N, and D. The equipment settings and final product properties differ slightly for each variation. Detailed information on the properties is available upon request or at web site www.scscoatings.com.
The Deposition Process
The Parylene polymers are deposited from the vapor phase by a process that resembles vacuum metallizing. Unlike vacuum metalization, which is conducted at pressure of 1x10-5 Torr or below, the Parylenes are formed at around 1x10-2 Torr. Unlike vacuum metallizing, Parylene deposition is not line-of-sight and all sides of an object to be encapsulated are uniformly impinged by the gaseous monomer. This is responsible for the truly conformal nature of the coating.
The deposition process consists of the following steps done in the presence of a medium vacuum:
1. Vaporization: Parylene is vaporized from its solid dimer form. This is accomplished by the application of heat under vacuum.
NOTE: The appropriate term for passing directly from a solid to a gas is sublimation. However, the industry has conventionally used the term vaporization in conjunction with the Parylene process. This convention is maintained throughout this manual.
2. Pyrolysis (cleaving) of the gaseous form of the dimer into a monomer is achieved by using a high temperature tube furnace.
3. Polymerization of the gaseous monomer occurs at room temperature as the Parylene deposits as a polymer onto the substrate in the vacuum chamber.
What the Tool CAN do
You can use default Positive Photoresist on Silicon recipe to measure the Parylene-C film coated on bare silicon TW, as the refraction index is the same 1.64. For other types of Parylene film, you can specify the refraction index in the program.
You have to use a shadow mask to etch the Parylene film under O2 plasma (Dryteck etc)
3. Woollam interferometer
The following people make up the Tool Quality Circle:
If desired, you can achieve improved adhesion of the Parylene film to your substrate by the following procedure. This procedure was adapted from the Berkeley Microlab Laboratory Manual.
1. In a 1000 mL glass beaker, mix 400 mL of isopropanol, 400 mL of DI water, and 4 mL of A-174 adhesion promoter.
2. If the mixture is to be used immediately, stir continually for 5 min every 10 min for a period of 2 to 2.5 hours. Or else, leave the mixture overnight.
3. Remove wafer from mixture and allow to air dry for 30 mins.
4. Soak wafer in IPA for 5 min.
5. Dry wafer with air gun.
6. Bake in oven at 115ºC for 30 min.
7. Collect the waste in a bottle.
8. Rinse the beakers with DI water once and dispose of this rinse water in the waste bottle. The bottle must be tagged and put in the secondary containment bins for EHS pickup.
SCS Parylene Deposition - Mini Spec
· Check logbook or badger for issues from previous run.
· Verify a) Main Power On, b) Emergency Stop UP, c) Furnace /Chamber Gauge DISABLE, e) Vaporizer DISABLE, f) Vacuum on HOLD, g) Chiller Off.
· Check the pump old and notify super-user or staff if a pump oil change is needed.
Operation & Verification:
1. Enable equipment in the badger and fill out the log book.
2. Vent chamber (Vacuum to VENT), inspect the cleanness of the chamber and cold trap. Follow section 8.5.9 and 9.2 to clean the old trap and chamber if necessary.
3. Prepare an aluminum foil boat and fill with appropriate quantity of Parylene dimer. Record final parylene weight in logbook.
a. Cut foil into a rectangle about 3.5 x 6 inches;
b. Curl the foil around the cylindrical former to form a “boat”.
4. Load Parylene dimer/boat. Close vaporizer door. The Parylene dimer/boat should be just inside the vaporizer, not close to the furnace.
o Load samples with a bare silicon wafer or piece for thickness characterization.
5. While holding cold trap thimble, turn Vacuum to VACUUM.
6. Wait for pressure going below 200 mT. then turn on the chiller.
7. Wait 10-15 minutes for chiller pump to warm up if starting from cold; you should see the green light is on near the chiller switch.
8. Verify all the setpoints are in correct values.
9. Press the green Process START/STEOP button to start the PLC program in auto mode
10. Turn Furnace/Chamber Gauge control switch from DISABLE to ENABLE.
11. Turn Vaporizer control switch form DISABLE to ENABLE.
12. The deposition process takes at least 30mins or several hours to complete, depending on the dimer weight put in the boat. You should make sure the furnace temp is approaching the setpoint before you leave for a long run.
13. Once completed, the green Process Start/Stop light will flash and all the heaters are turned off automatically. Press Process Start/Stop button and green light will turn off.
14. Toggle Furnace/Chamber Gauge to DISABLE and Vaporizer to DISABLE. Turn OFF Chiller and WAIT 60 MINUTES (for heaters to cool down and cold trap to warm up).
15. To vent chamber, set Vacuum to VENT. Verify tool at atmosphere by checking cold trap thimble. Lift Lid, unload Samples and remove the dimer aluminum foil boat.
16. Inspect and clean the tool, particularly the cold trap thimble, chamber lid and O-ring with steps below:
a. Put on a second pair of gloves over the first pair;
b. Rinse the cold trap with Micro90 2% in DI Water;
c. Scrape off the Parylene deposit with a Soft Scrub pad;
d. Wipe lightly with a lint free cloth - leaving the trap slightly moist;
e. Gently wipe off visible particles inside the chamber, lid and o-ring with cleanroom wipes and slight IPA solution;
f. Change gloves after this operation to prevent tool or clean room contamination from electrostatic Parylene particles. (i.e. Pull of the second pair of gloves).
17. Replace the Lid. Set Vacuum to VACUUM to pump down.
18. Shutdown. Verify Chiller Off, Furnace/Chamber Gauge to DISABLE, Vaporizer to DISABLE, process START/Stop light is Off; when the chamber pressure is below 100mT, you can turn the Vacuum position to HOLD.
19. Characterize the deposited film thickness, and fill out logbook completely.
20. Disable the badger, report in the badger and notify SNF Lab Staff of any tool or process issues or the chamber inside wall is starting to peel off.
21. Clean the area. Enjoy your work!
Recommendation to users with critical processes
Dimer weight (g)
A174 Promoter Used (Y/N)
Film thickness (A)
main etching species should be Oxygen plasma based
1/24 drytek2 (cont) descum recipe: 320~330 A/min
amtetcher (semi-clean) prog4 Via recipe: ~160A/min
1. O2 plasma in gasonics or matrix may be too aggressive to etch parylene film when you try to remove PR