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-- TimBotzem - 2012-07-01

RECIPE FOR QD FABRICATION

Preliminary preparation

- Cut the wafer with photoresist on it (soft baked for 2 min)

- Clean off the resist

Mesa

- Clean the wafer with acetone and IPA

- Spin resist AR-U 4040 30 sec @ 6000rpm

- Bake at 100 oC for 2 min

- Exposure for 10 s

- Develop in AR 300-47 for 30 s and then flush in water and blow dry

- Check under the microscope

- plasma asher prog 5

- post-bake for 2 min @ 110

Mesa etching

- Etching solution: Add successively 100 mL water, 3 mL H2O2 (30%) , 3 mL H2SO4

- wat 30 min

- Etch for a convenient time (rate: 28 A/s) and then flush in water and blow dry

- Wash off the resist with acetone and IPA (5 min warm) and measure the height

Ohmic contacts

- Clean the wafer in acetone and IPA and blow dry

- Just before spinning the resist take out from the IPA and blow dry

- Spin image reversal AR-U 4040 for 30 s at 6000 rpm

- Bake for 2 min @ 90 oC , let cool

- Expose for 15 s

- Bake for 5 min @ 115 oC and let cool

- Flood expose for 45 s

- Develop in neg Developer for 25 s and then flush in water and blow dry

- plasma asher prog 5

Ohmic contact evaporation

- HCl-dip (HCl:H2O 1:1) for 20 s, flush in water and blow dry

- Ni 50 A (0.06 A/s), Au 2000 A (0.3 A/s), Ge 1000 A (0.25 A/s), Ni 750 A (0.2 A/s)

- Lift-off in warm acetone

- Annealing (RTP) : 150 C for 60 s , 330 C for 40 sec, ramp to 460 C in 10 sec , 460

C for 50 sec

E-beam gates

- First layer: 639.04 30s @ 6000 rpm

- Bake @180 oC for 5 min

- Second layer: 679.02 30s @ 6000 rpm

- Bake @180 oC for 5 min

- After e-beam writing develop in AR 600-55 for 75s (last 5 s with ultrasonic) and flush in IPA

- Standard recipe for evaporation 5 nm Ti, 20 nm Au

- Lift-off in warm acetone

Optical gates

- Clean the sample with acetone IPA

- Spin image reversal “AR-U-4040” for 30 s at 6000 rpm

- Bake for 2 min @ 90 oC and let cool

- Expose for 15 s

- Bake for 5 min @ 115 oC

- Flood expose for 46 s

- Develop in “neg Developer” for 25 s and then flush in water and blow dry

- plasma asher prog 5

Optical gates evaporation

- HCl-dip (HCl:H2O 1:1) for 20 s, flush in water and blow dry

- Evaporation: Ti 250 A (0.1 A/s), Au 2000 A (0.25-0.35 A/s)

- Lift-off in warm acetone

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Topic revision: r4 - 2013-05-16 - TimBotzem
 
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