Si cryogenic etch 70 nm holes - NanoLabStaff/nanolab GitHub Wiki

by Vilde Sørdal ([email protected])

  1. Chamber clean

     Wipe down chamber with cleanroom wipes with isopropanol and DI water. (Ask a NanoLab engineer for this.) It may not be necessary to do this step.

  2. Chamber condition

     Step 1: 1500 W ICP, 100 W CCP, 40 sccm O2, 40 sccm SF6, 20 degrees C, 15 mT, 30 min.
 Step 2: 1000 W ICP, 100 W CCP, 7 sccm O2, 21 sccm SF6, 20 degrees C, 15 mT, 30 min.
 Step 3: Run the exact recipe to be used for 30 min.

  3. Sample mounting

     Apply a thin layer of Fomblin oil to a 4" Si carrier wafer and place your sample on top. (No oil must be visible.)

  4. Strike

     Strike plasma at 15 W CCP. As soon as the reflected power starts to decline rapidly, change the power manually to 6 W.

  5. Standard etch recipe:

     SF6: 45 sccm
 O2: 21.2 sccm
 RF power: 6 W
 ICP power: 1000 W
 T= -120 °C
 Helium pressure: 15 torr
 Chamber pressure: 8 mtorr
 Etch rate: 27 nm/s
 Selectivity, Si:PMMA 2.3:1

This recipe is for etching of holes of 70 nm diameter with PMMA as a mask. The PMMA is patterned with EBL beforehand. sietch

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