Wafer Thinning

• Turn hot plate on to level 4 (corresponds to ~130C)

  • Crystal bond melts at 121C

• Measure the starting thickness of the sample

  • Zero out the thickness measuring tool by dropping the arm and pressing “zero”

  • Place the sample under the arm, drop it to measure the starting thickness

  • To replace the battery, twist the face and pull off to pop out watch battery

• Get the “step 1” holder

  • Only “step 1” is needed to sufficiently thin the wafer for a good cleave

  • Steps 2-3 are for wafer polishing (might be necessary for reflection/transmission measurements)

• Take out the glass chuck from the “step 1” holder, stick the “step 1” silicon carbide paper onto it

• Replace the glass chuck into the holder and fit the holder into the thinning machine

• Place the sample holder (stored in Briggs’ box) onto the hot plate and let it heat up

• Use the razer to chip off some chunks of crystal bond and use the crystal bond tools to place a pea/dime sized amount of the chunks onto the sample holder

• When the crystal bond is melted, place the sample epi (or glass slide) down (substrate up)

  • Rotate sample a bit to even out the crystal bond

  • Don’t let it sit on the hot plate too long or the resist can get over-baked

• Remove the sample holder (use 2 pairs of tweezers) and let it cool for 5 minutes

• Spray DI water on the sandpaper (quarter-sized amount)

• Place the sample substrate down and connect the sample holder to the thinning tool arm

• Press go (covered in slurry) and let run for 30 minutes

• When complete, lift up and remove sample holder

• Drop sample holder on hot plate and remove sample using crystal bond tools

  • Let crystal bond solidify before placing sample down anywhere

• Take out holder and peel off sandpaper

  • Wipe with acetone

• Remove wafer bond from sample holder with acetone

  • Clean off with acetone in acetone dish

  • Dump dish down “sink” (ensure waste jug not full)

  • Wipe down

• Measure thickness of sample at this point

• Repeat steps 3-17 as needed

• Turn everything off and put away

Attaching to a Glass Slide

• Cleave off a square of a glass slide in the bat cave

• Heat up hot plate to 90C

• Place the sample at the resist spinner an apply thick resist at 2000 rpm for 40 sec

• Splat the sample epi down onto the center of the glass slide (substrate exposed)

• Place the glass slide down onto a hot plate at 90C for 1 minute

• Check to make sure it is indeed bonded together

Removing the Glass Slide and Gunk

• Fill the PG remover dish with PG remover

• Place sample + glass slide combo in the dish and gently (GENTLY) slide the sample off

  • Use 1 pair of tweezers to push the sample parallel to the glass slide and use another pair to push against the glass slide

• Fill the acetone dish with acetone

• Move the now-free sample to the acetone dish and let swim in acetone to remove the rest of the resist and any residual III-V gunk

  • If lots to remove or going slow, make a little foil hat and let soak in acetone overnight

  • Can also sonicate if it still won’t budge (carefully!!!)

• Toss the glass slide in arsenic trash

• Fill the IPA dish with IPA

• Soak the sample in IPA to finish cleaning