Chip Etching SOP
Upon entering, turn on hot plate(s) to 110oC (Marked at number 3 on dial). Turn on the lights in the hoods.
Turn on UV Lamp and timer
Place white hose into hood to avoid ozone build up.
Lamp readout should show 5 amps and 60 volts
Record time lamp is turned on
After it has warmed up, test the lamp exposure (should read above 50)
Remove the appropriate coated glass plate from the box
Record Lot # and glass type in your cleanroom notebook
Be sure not to expose glass to white or UV light
Do not touch coated surface of the plate
Clean glass and blow dry with N2 if necessary
Be sure to record how many pieces were removed from box
Recover the remaining coated glass plates so that they are not accidentally exposed.
Clean Mask if necessary with N2, never with water
Put together coated glass/mask sandwich
Place plain glass piece on bottom (wet slightly)
Place glass plate with photoresist up on top of this piece
Place mask on top of photoresist with the shiny side up
Place second plain glass piece on top to complete “sandwich”
Move into position under UV lamp light
Center glass “sandwich” under UV light (entire setup will not fit within the light circle)
Expose Photoresist
Put shield around lamp and sandwich
Hit expose button on the lamp timer (we usually expose for 5 seconds)
!!! DO NOT LOOK AT THE UV LIGHT !!!
After exposure turn lamp off if finished and record total time used.
Develop
Pour photoresist developer (not stripper!) into labeled crystallization dish
Place exposed chip into developer and rock container until pattern appears.
Remove using tongs, rinse with water, then dry with nitrogen
Pour used developer into appropriate waste bottle and rinse crystallization dish
Bake chip on hot plates for 30 minutes at 110°C to set photoresist
Remove Exposed Chrome
Pour chrome etch into labeled crystallization dish
Place glass plate into etchant and rock until chrome is completely removed (over etch as opposed to under etch to ensure that chrome is completely gone)
Remove using tongs, rinse with water, then dry with nitrogen
Pour used chrome etchant into appropriate waste bottle and rinse crystallization dish
A second bake step for 30 minutes at 110°C is recommended, but not required.
At this point you can either save the chip for later etching or continue on with etching
Taping
If necessary, use HF resistant tape (blue) to protect areas of your design that you do not want etched straightaway.
Etch Plate
Use appropriate etching solution for your type of glass
Carefully open container holding the etch solution
Place glass plate into etch solution and begin timing.
Place etch solution and chip on rocker for appropriate amount of time
When etching is complete, or for measurement, remove plate from solutions using tongs and immediately place into water to stop etching. Immediately place the cover back on the etching solution.
Rinse thoroughly with water to remove all HF
Record the date you used the solution, your initials, and the duration of the etch in the cleanroom notebook.
Determining depth of etch
After etching, rinse and dry the glass plate
Use the profilomter to measure the depth of the etch. *Note: the profilometer only reads to about 90 µm, so if you require deeper etching you will need to do it in steps.
Calculate and record the etch rate in the cleanroom notebook and on the etch solution’s log (found on the side of the etching hood).
Remove Photoresist
Pour photoresist stripper into labeled crystallization dish and place on the hot plate (heating helps to remove the stripper faster)
Carefully place glass plate into solution
Gently rock until all of the photoresist is removed (color change from red/green to brown)
Remove plate with tongs, rinse with water, and dry
Place used stripper into the appropriate waste bottle and rinse crystallization dish
Remove Remaining Chrome
Pour chrome etch into labeled crystallization dish
When finished (chip will now be colorless) remove with tongs, rinse and dry
Pour used chrome etchant into appropriate waste bottle and rinse crystallization dish
Congratulations, you have etched a chip!
Be sure to clean up properly
Throw away all lint free cloths
Wipe up any water spills
Make sure developer/photoresist remover/chrome etch are disposed of in appropriate waste container and rinse all glass containers with water.
Be sure hot plates are turned off
Be sure lamp is turned off
Turn off hoods
Turn off lights in room