• Goal: set RP2-B0 in wax on Allied sample holder
• RP2-B0
  • Decapped 2x “live” from photo shoot to bare die
  • Around 277 um thick. Later measurement 281 um
• Sacrificial dies
  • Samsung k4h560438e-tcb0
  • 324 um
• Area
  • Samsung: 5.3 x 11.1 = 58.8 mm2
  • RPI: maybe 4 mm2
  • Net: maybe 60 mm2
• Etchant: 20% w/v KOH in water
  • https://cleanroom.byu.edu/koh
  • Approx 250 um / hour heated ⇒ 4.15 um / min
• Etch
  • Etch 1
    • 25 min @ 177F hotplate
    • 306 um
  • Etch 2
  • 30 min?
    • raised temp?
    • 297, 302 um
    • High spots forming (was warned might be uneven at this conc)
  • Etch 3
    • Now hotplate at 220F
    • 286 um, 291 um
    • 14 um in 30 min
    • (286 - 277) * 2 = 18 more min?
    • Lots of metal flaking off
  • Etch 4
    • 20 min
    • Ultrasound. Lots of stuff flaked off
    • Didn't note final thickness…
• Check all dies for thickness before mounting
  • Not all started at exactly the same time, although was close
• Order replacement lapping gauge
  • 543-452B, ID-C125EB
    • 1 um resolution
    • 25 mm travel
    • Long
    • Flat carbide tip. Will need to switch to new unit
  • Skips
  • Can't modify spares to be long enough
  • One that might work I can't get to power up. Completely broken?
• Set in wax
  • 0.4 mm gap in area(s). Not ideal but may still work

Goal: setup lapping machine, lap RPI chip from other day

TODO:

• Level head
• Review Allied recommendations
• Characterize um / rev
  • Gauge skips, but is stable over say 1 mm
• Setup slurry feed
  • Can I make this nicer?

Inventory:

• 2x MultiPrep systems w/ arm
  • Both were surplus / in bad condition
  • One is more “ready to go”
• Lots of lapping disks
• Is my old colloidial silica still good?

Notes:

• Installed old magnetic polishing cloth