Cambridge ALD

Cambridge ALD

Essentials
Full name	Savannah S100 (gen. 1)
Manufacturer	Cambridge NanoTech (Veeco)
Description	Atomic layer deposition system
Location	Cleanroom 1 (03.2.209A) Cleanroom 2 (03.2.203B)
Responsibility
Primary	Harry
Secondary	Martin

Two nearly identical Savannah S100-like systems are used for atomic layer deposition of aluminum, hafnium, and titanium oxide.

Other material deposition alternatives at the NBI cleanroom:

• AJA systems for sputtering/e-gun evaporation
• E-Gun evaporator
• Edwards thermal evaporator
• Leica sputter coater
• Molecular beam epitaxy system

Growth per cycle (GPC) monitoring

• 
  ALD1 HfOx
• 
  ALD1 AlOx
• 
  ALD2 HfOx

Available processes

Deposited material	Precursor	ALD1	ALD2	Ref.
Hafnium oxide (HfOx, HfO2)	TDMAH tetrakis(dimethylamino)hafnium [(CH3)2N]4Hf	Yes	No	[1]
Aluminum oxide (AlOx, Al2O3)	TMA trimethylaluminum (CH3)3Al	No	Yes	[2]
Titanium oxide (TiOx, HfO2)	TTIP Titanium(IV) isopropoxide (CH3)3Al	Yes	No	[3]

Videos on operating the tools

Video on how to operate ALD 1:

• Click here to watch the video on YouTube

Video on how to operate ALD 2:

• Click here to watch the video on YouTube

Standard operating procedure

• Log your process in the Excel notebook.
• Check the nitrogen bottle:
  • Verify that the main valve on top of the bottle is open.

  The N2 flow in idle state is 5 sccm.

  • Verify that the main bottle pressure is at least 5 bar.
  • The line pressure should be >1 bar (ALD1) 1-2 bar (ALD2).

  If line pressure is outside the range, please report it to the cleanroom staff.

• Make sure the valves of all precursors inside the ALD machine are closed.
• Run recipe Default_cleaning to pump out any residual gas in the gas lines.
• Press the VENT or VENT REACTOR button.
• Open the metal lid.
• Put your sample inside, roughly in the center, away from the gas inlet and outlet.

  Check whether the rubber O-ring is properly seated.

• Close the metal lid. Check that the lid is aligned to sit directly on top of the reactor chamber.
• Press the PUMP or PUMP REACTOR button.

  Pressure with flow set to 0: ~5e-2 Torr or lower.

• Place the metal cage on top of the tool.
• Open relevant precursor valves.
• Run your recipe.

• Pressure with 20 sccm N₂ flow present: low e-1 Torr.
• ALD1 pulse lengths: H₂O ~0.5 s, HfOx TDMAH 0.2 s, AlOx TMA 0.02 s.
• ALD2 pulse lengths: H₂O ~0.02 s, HfOx TDMAH 0.2-0.5 s.

• Close precursor valves.
• Press the big round VENT or VENT REACTOR button.
• Place the metal cage on the side of the tool.
• Take out your sample. Check the rubber o-ring.
• Press the big round PUMP or PUMP REACTOR button.
• Run recipe Default_heater_set.
• Verify that the flow is set at 5 sccm.

Witness samples

In CR1 and CR2, you can find various witness samples depending on the properties that you would like to explore:

• Only thickness: Si (001) of dimension > 7x7 mm2
• Thickness and breakdown voltage: Si (001) 15x15 mm2 back-side Au plated

It is recommended to ash the witness chips for 2 mins before loading them in the ALD tool.

File logs

• Recipe file location

  ALD1: C:\Savannah\Users\Standard\

  ALD2: C:\Cambridge Nanotech\Recipes\

• Log file location

  ALD1: C:\ALD data. Includes pressure data, screenshot at termination.

  ALD2: C:\Cambridge Nanotech\Log\. Includes pressure and heater temperature data, screenshot at termination, software event logs.

Troubleshooting

Pressure reading obviously wrong (above 1e3 Torr or below 1e-4 Torr)

Pressure gauge failure. Unplug the network cable from the small square pressure gauge beneath the chamber and plug it back in. The pressure reading should return to expected values.

No peak visible during precursor pulse

• Precursor valves closed. Make sure the relevant precursor valves are open. Consult the labels on the inside of the door.
• Pulse time too short. Select the lowest plotting interval and check whether you can spot a small peak when the automatic valve opens. Increase pulse time as needed.

Cannot open lid upon venting

• Chamber pressure still below atmosphere. Confirm pressure reading in software. If pressure is below 5e2 Torr, check whether the nitrogen bottle valve is open.
• Rubber O-ring can get stuck to the lid. Gently but firmly lift the lid. Reseat the O-ring if needed.

What is the best plot time to graph the process pressure?

It is recommended to plot only several pulses, for example 30 seconds or 1 minute total plot time. Setting this value to 1 hour during a run can reduce delay precision, because with a 1 hour plot time many data points need to be refreshed, which consumes a lot of processing resources. It is possible to set the plot time to 1 hour to get an overview of pulse heights, but plot times > 5 minutes are not recommended during a run.

What are the recommended heater temperatures?

These are the recommended temperatures from the manual:

• Heaters for the trap (#6):150°C
• Stop valve (#7): 150°C
• ALD valve oven (#10): 150°C
• Precursor Manifold: 150°C
• Reactor heaters (#8 and #9): 100-200°C
  • ALD1 (#8 and #9): 110°C

Remote access

• TeamViewer: ALD1, ALD2
• LogMeIn: ALD1 (CR1), ALD2 (CR2)