1. Solvent user safety
All wipes that have been used with solvents should
- Room 128: put in dustbin inside fume hood
- Room 129: put in small dustbin with lid. Transport to fume hood in room 128 when finished
2. Turn on hot plate 1(20 min before wafer cleaning)
Equipment needed:
- VWR spec-wipe wipers
- Isopropanol
Procedure
- Open LAF bench
- Wipe off the hot plate with VWR spec-wipe wipers and isopropanol clean [VWR hot plate]
- Power on VWR hot plate and set its temperature 150 celus degree.
3. Cleaning of wafer
Equipment needed:
In room 128:
- Wafer
- Wafer tweezer
- Glass petri dish
- Acetone in spray bottle
- Isopropanol in spray bottle
Procedure:
In room 128 fume hood
- Rinse with acetone
- Put wafer in glass petri dish with isopropanol before acetone has vapourized
- Rinse glass petri dish with isopropanol [Repeat the process several times - rinse with isopropanol]
- Dry with nitrogen gun
- Transport to LAF bench in room 129
- Put on hot plate, keep lid off
- Leave the wafer on the hot plate until the temperature (red number - stable number) has been stable above 140 C for 5-10 minutes.
- Turn off the hot plate so it may start cooling for next step
4. Program spin coater [GM1070 datasheet]
- Power on and vacuum switch to “manual”
- Look up in table spin speed for desired thickness
- Check the existing spin-coater programs for the procedure and speed you want
- Choose an appropriate program or make a new one, and record what the new program is
- Go through the program to check that it is correct
- Put the correct choke on the spinner
- Put the test wafer on the choke and close the lid
- Turn on the vacuum pump
- Push the blue button to run the spin sequence and verify the sequence
- Turn off vacuum pump (if desired)
Put on a wasted waffer to test and make sure the program is correct
Spin coater: To get a good results, should spin two step, one low speed to spread PR over the wafer and 1 high speed to reach the thickness. When pour PR, avoid bubbles, should pour more PR volume to cover all the wafer) (test today: 10s at 500, 40s at 900, ramp 100)
5. Spin coating SU8 on wafer
Preparation:
- Look up in table how much SU8 must be applied depending on the size of the wafer and the desired layer thickness
- Turn off white light in room 127, 128 and 129, turn on yellow light and move down the blinding curtains.
Equipment needed:
- SU8
- Disposable container or syringe
Procedure:
- Put wafer on chuck (well centred)
- Turn on vacuum (to fix wafer on chuck)
- Transfer desired amount of SU8 from bottle to disposable container
- Transfer desired amount of SU8 from disposable container onto centre of wafer
- Close the lid and push blue button
- Turn off the vacuum
- Leave the wafer in the spin coater with the lid on for [~1 hour for relaxation] - Based on the process
Prebake
- Check that the hot plate temperature is below 50 C
- Set the time parameter in the hot plate program to that suitable for your thickness
- Press “P” to go through the parameters of the program
- Turn off white light, turn on yellow light
- Remove wafer from spin coater and remove any SU8 from the underside of the wafer
- Put wafer on hot plate (on top of aluminium foil) and close lid
- (turn off yellow light if desired)
- Press “U” to start the program (green dot behind green number should light up)
- After program has finished
Alternative 1
- Leave the wafer under the lid in the hot plate until the temperature is less than 50
- Turn off white light, turn on yellow light
- Open lid, move wafer to Teflon slab
- Let the wafer cool for XX minutes
Alternative 2
- Turn off white light, turn on yellow light
- Open lid, move wafer to Teflon slab
- Let the wafer cool for YY minutes
Prepare the mask during prebake
- Open and turn on the LAF bench (and leave it on)
- Take the transparency mask out in the LAF bench
- Clean a mask glass [isopropanol in room 128] and place it on centering pattern
- Cut out your pattern
- Put the reflecting side of the film towards the glass [the printed inside attach to waffer, check the edge to find out the ink side]
- Place the mask in the centre of the glass and fasten with two small pieces of tape
Exposure
- Keep white light off, yellow light on
- Calculate UV-KUB settings
- Turn on the UV-KUB (power button behind and in front)
- Open drawer (how)
- Move wafer from Teflon slab to UV-KUB
- Put glass with mask on top (mask should contact wafer)
- Close drawer
- White light can be turned on
- Set UV-KUB settings
- Expose
- Leave the wafer to relax inside UV-KUB for 5-10 minutes
Postbake
- Change the hot plate settings to post-bake or leave the settings to remove manually after 40 minutes at 95 C
- Wait until hot plate temperature is less than 35 C
- Turn off white light, on yellow light
- Move wafer to hot plate
- White light can be turned on
- Run program…….
- 10 min relaxation
Development
- Turn off white light in room 128 and 129, yellow lights on - put the light off sign on the door - 127
- Pour the PGMEA into beaker in the fume hood in room 128
- Move wafer to fume hood in room 128
- Place wafer in wafer holder
- Set timer to XX minutes (calculated from…)
- Put wafer holder with wafer into PGMEA at the same time as the timer is started
- When timer beeps take wafer out and rinse with isopropanol
- Dry with nitrogen
- Put wafer under stereo microscope (outside the fume hood - room 128)
Hard bake (white light is OK)
- Put the wafer in a glass petri dish to keep dust off
- Put dish with wafer in cold oven
- Turn temperature set point to 135 C
- Leave it in the oven for 3 hours and let it cool slowly