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====== Description ======
The UHV system is a magnetron sputtering system with a background pressure around 10e-10 mbar and a deposition pressure of 1e-3 to 1e-2 mbar. It is equipped with a loadlock that holds a sample garage with 7 sample spaces. One sample space can hold a 15x15mm wafer. The substrate is transferred to and from the chamber using two linear manipulators and a wobble stick. Most targets in the chamber are at an angle with respect to the sample, and the sample can be tilted towards 3 out of 4 magnetron sources. The system can be used with both DC and RF power supplies (DC being standard). The sputtering gas is Ar; the loadlock is also connected to N<sub>2</sub> and O<sub>2</sub> for oxidation. The substrate stays relatively cool and cannot be cooled or heated away from room temperature.

The UHV system is maintained by the nanolab and the Lahabi Lab. Contact the Lahabi Lab if you are interested in using the system. Target changes are only performed sporadically, to maintain excellent vacuum conditions.  

======The Vacuum System======
To keep the chamber conditions UHV, it is never vented to atmospheric pressure. Instead, samples are first pumped down to 5e-8 mbar inside a small loadlock. Samples are transferred from loadlock to chamber and back while the chamber is at an Ar overpressure with respect to the loadlock. This ensures contaminants from the loadlock cannot reach the chamber. 

The pressures in loadlock and chamber are read out via ion gauges on the black panel below the system. IG1 reads out the chamber, while IG2 reads out the loadlock (always double check with stickers). When the light is on, the gauge is on and it is also being read out. **Ion gauges can explode when operated at high pressures, so you should never vent or let in any gas with the ion gauge on.** A third gauge is located on one of the chamber sides and is used to gauge the chamber pressure when Ar flows into the chamber. It automatically switches between an ion gauge and a pirani gauge, so that it works at sputter pressures.

The system also has intermediate vacuum gauges behind the loadlock and chamber turbos. These are marked A and B on the black panel respectively. The Ar monitoring ion gauge has a separate controller on the rack. 


====== Manual ======

===== Before you start =====
First check the logbook to see if you are interfering with someone else. Users write down their names upon loading their samples. So fill in your name and the date before starting your loading procedure!

===== Venting the loadlock and loading the substrates: =====
  - **Never touch anything inside the machine without wearing clean, powder free gloves.**
  - Sampleholders are kept on the workbench in the sputterlab, inside the petri dishes. Always clean your sampleholder with acetone and IPA before starting.
  - Glue your sample onto the sampleholder with a small amount of silver paste. Let it dry (approximately 10 minutes). You should be able to hold your precious sample upside down!
  - Turn off the loadlock ion gauge (IG2). Monitor IG1 while venting. If it starts increasing, you are probably making a mistake. 
  - Check if the gate valve between loadlock and chamber is fully closed. Clockwise = close.
  - Turn off the loadlock turbo on the turbo controller panel. 
  - Close the valve of the rotary pump. Clockwise = close. This closes off the rotary pump. 
  - Let the turbo spin down for 1 minute. Then very slowly and carefully let in a bit of N<sub>2</sub> using the N<sub>2</sub> valve on the bottom panel (max. 25 mbar on the gauge *behind* the turbo at this stage). Listen to the turbo pump to fully spin it down. Take your time! Spinning down the turbo should take about 5 minutes.
  - When the turbo has stopped, vent the system completely with N<sub>2</sub>. The loadlock door will burst open, so stay clear. The chamber pressure can sometimes increase to 1e-8 mbar range because of a leaky gate valve. This means work quickly!
  - Put your sampleholder inside the garage with the long side towards you. Always wear gloves, and use long metal tweezers. Take care to maintain N<sub>2</sub> flow, such that water vapours cannot enter the loadlock. 
  - Close the loadlock. The door needs to be in perfect alignment, so tilt it a little if uncertain. You should see absolutely no gap between the loadlock and the door. As you close the door, also close the N<sub>2</sub> valve. 

===== Pumping down the loadlock: =====
  - Open the valve to the rotary pump. 
  - The pressure should start decreasing almost immediately. If it does not decrease, close the rotary pump valve and check if the door is properly shut. 
  - When the pressure on A (the loadlock intermediate pressure gauge) goes below 5 mbar, switch on the loadlock turbo.
  - When the turbo reaches its max rate, turn on IG2. The turbo can take up to 5 minutes to spin up fully. The heat of IG2 will help pump the system down. 
  - Pump until base pressure (<5e-8 mbar) in the loadlock has been reached. This could take up to 12 hours.  

===== Sputtering: =====

**Pre-sputtering**
  - Fill in logbook
  - Turn on cooling water. There are two valves at the back of the instrument (blue labels on the left).
  - Take care that the sources are connected to the DC switch box. They could be disconnected, especially after a bake-out.
  - Turn off all IGs on the black panel. 
  - Open the shutter that you are going to use. Make sure all other shutters are still closed. 
  - **Fully close the NV.** The needle valve is the black needle valve behind the black gas panel. CW = close. **Otherwise you will flood the chamber with Argon!** Don’t force the NV.
  - Close the valve conductance to 10%. Otherwise the turbo will just pump all the argon away.
  - Turn on the argon-measuring gauge (Pfeiffer controller on the rack). Give it a minute to warm up. It should report underpressure (ur=under range) or some small number, as its range is limited to 1e-6 mbar. This dual-gauge is not accurate calibrated below 1e-5 mbar. You can turn it on at the back of the rack.
  - Slowly open the argon line on the black panel.
  - Gradually open the NV and let in ~2e-3 mbar of argon pressure. It takes some “human PID” to get this right. N.B.: even when the NV is fully closed, there is still a substantial flow through the NV. This does not mean that the needle valve is broken; all needle valves have this to some extent. 
  - Now use the valve-conductance controller to regulate the pressure for your sputtering process.
  - Select your target on the DC-switching box.
  - Power on the MDX-1K DC power source. **Never operate the DC-switching box with the power source on!**
  - Set the setpoint of the power source to the one for your target.
  - Close all window shutters! Also the one for the light.
  - Ignite the plasma by pressing output on. **Never switch the output by turning the power to the source on or off, always use the output on/off buttons.**
  - When finished with presputtering press output off. The plasma should extinguish and you can open the window shutters again. 
  - Turn off the power supply. If you want to sputter multiple materials, pre-sputter every material, taking extra care that you are opening/closing the right shutters. 


**Loading**
  - Open the gate valve. The argon will also flow into the loadlock turbo now. This will decrease the argon pressure to about 1e-3 mbar. Open all the way! **Never open the gate valve without argon overpressure!** 
  - Make room for the garage by moving the sample holder far away from the center of the chamber. 
  - Put the garage in such a position, that you can easily take out your sample with the manipulator.
  - Slowly and carefully take out your sample from the garage with the manipulator and put your manipulator in the “standby position”.
  - Now drive the sample holder into a comfortable position.
  - Use the manipulator to “put down” your sample. Be careful that the beak does not smack your sample out of the holder. 
  - Now place your sample in the middle of the chamber. The correct position is marked on the linear manipulator with black marker.

**Sputtering**
  - If necessary, tilt your sample to the right sputtering angle.
  - Check the pressure. If necessary, adjust back to your preferred sputter pressure.
  - Check the shutters.
  - Check that you have the right Ar-Pressure, Current Setpoint, tilt angle, the shutter of the target is open, and that you know the sputter duration.
  - Close the window shutters
  - Update the logbook.         
  - Press output on and time your sputtering process
  - Monitor the process periodically. The source has at some point turned itself off when sputtering long times (>20 minutes). 
  - When finished, press output off. 
  - Turn off the power supply. If you want to sputter a different material, start again with pre-sputtering. 
  - Close all used shutters. 

**Finishing**
  - Drive back your sample to a place where you can easily grab it with the manipulator
  - Grab your sample with the manipulator and drive the sample  holder back
  - Now open the gate valve. Ar pressure should decrease again. Drive the garage into a comfortable position and load your sample into the garage. 
  - If you need to sputter multiple samples, exchange sample and sputter again. 
  - Drive back the garage and close the gate valve fully. Ar pressure should return to the level you set before. 
  - Close the Ar valve on the gas panel fully. 
  - First pump out whatever gas remains, by opening the valve-conductance to 100%. The red “open” light should remain on and the Ar gauge should go to 1e-4 mbar range. This is because there is still gas in between the needle valve and the Ar valve. 
  - Open the NV fully. Once the dual-gauge goes below 5e-6 mbar, the chamber is empty and you can now turn it off.
  - Turn on IG1 again, and check that the chamber is returning to UHV conditions. 
  - Switch off cooling water.
  - Vent the loadlock as described above in order to remove your samples
  - Always pump down the loadlock after use (as described above).

===== Bake-out: =====
To achieve a high-quality vacuum after the chamber has been vented, a bake-out is required. A good bake-out should take at least 48 hours to properly heat the whole system.

  * Turn on the cooling water
  * Disconnect the HV cables from the targets
  * Remove the Ar gauge
  * Cover the viewports with aluminium foil
  * Place all the panels to fully cover the whole machine

The blue cables for the vacuum gauges do not need to be covered. To start the bake-out, flip the breaker switch up and turn the black knob to the left. This permanently turns on the heaters (will go between the two setpoints, should be 80 and 100 C). Turning it to the right will use a timer but this was found to be iffy. After the bake-out make sure to reattach all cables and the Ar gauge. Please be aware that there is no interlock preventing you from turning on the heaters without the cooling water. The cooling water must be on during the bake-out!

====== Deposition rates ======

RATES AFTER THE BIG MAINTENANCE OF 2025

All rates measured by Jibbe Reuver with tapping mode-AFM in June 2025. 

^ Material ^ Process parameters ^ Thickness ^ Rate (nm/min) ^ Rate (nm/s)  ^ 
| Co | 4.0e-3 mbar, 100 mA, 10 min          | 31.2 nm   | 3.12  nm/min | 0.052 nm/s  | 
| Cu | 4.0e-3 mbar, 65 mA, 10 min           | 136.86 nm | 13.69 nm/min | 0.228 nm/s  |
| Nb | 4.0e-3 mbar, 200 mA, 20 min, 45 deg  | 61.58 nm  |  3.08 nm/min | 0.0513 nm/s |
| Pt | 4.0e-3 mbar, 150 mA, 10 min, 45 deg  | 122.9 nm  | 12.29 nm/min | 0.205 nm/s  | 
| Pt | 4.0e-3 mbar, 100 mA, 10 min          | 111.37 nm | 11.14 nm/min | 0.1856 nm/s |
| Pt | 4.0e-3 mbar, 120 mA, 10 min          | 138.53 nm | 13.85 nm/min | 0.2309 nm/s |
| Pt | 4.0e-3 mbar, 100 mA, 10 min, 45 deg  | 87.8 nm   | 8.78 nm/min  | 0.1463 nm/s |

Definition: ''sputtering angle'' is the angle between substrate and target. If this angle is not zero, it should be noted here. Note that for sources 1 and 3 the substrate needs to be tilted 45 degrees to have a zero ''sputtering angle''.

**Small note on rate calibrations: it is our great preference that we do not calibrate with profilometer.** In the past, this has given wildly inconsistent results. While the profilometer setup has received some love recently, the working principle of the machine has not changed. Similarly, the "marker drop" technique, that is often used to estimate sputter rates, can give wrong rates even on AFM because it can lead to round ramps over the same length-scale as higher-order non-linearities in AFM piezos. The best method for rate estimation is to make a calibration sample at e.g. the EBPG, then run a liftoff and perform AFM on this sample. 

RATES BEFORE THE BIG MAINTENANCE OF 2025

^ Material            ^  Date    ^ Sample ID ^ Process parameters          ^ Measurement ^ Result  ^ Rate          ^ 
| Co                  | 20140916 | Co_cal    | 4.0e-3 mbar, 100 mA, 14 min  | X-ray       | 62.8 nm |  4.48 nm/min     |
| Cu                  | 20140916 | Cu_cal    | 4.0e-3 mbar, 65 mA, 5 min    | X-ray       | 53.6 nm |  10.72 nm/min     |
| Nb                  | 20140916 | Nb_cal    | 4.0e-3 mbar, 200 mA, 15 min, 45 deg  | X-ray       | 46.9 nm |  3.13 nm/min     |
| Nb                  | 20140925 | Nb_cal1   | 4.0e-3 mbar, 200 mA, 12 min 43 s, 45 deg  | X-ray       | 41.1 nm | 3.23  nm/min     |
| Nb                  | 20140925 | Nb_cal2   | 4.0e-3 mbar, 200 mA, 12 min 43 s, 45 deg  | X-ray       | 41.2 nm |  3.24 nm/min     |
| Ni                  | 20140916 | Ni_cal    | 4.0e-3 mbar, 150 mA, 14 min  | X-ray       | 67.8 nm |  4.84 nm/min     |
| Pd                  | 20160608 | Pd_cal    | 3.2e-3 mbar, 100 mA, 15 min  | profilometer| 108 nm |   7.2 nm/min     | 
| Py                  | 20170206 | Py_cal2 | 4.0e-3 mbar, 150 mA, 15 min | profilometer | 73.72 nm | 4.9 nm/min|

[[wiki:oldrates|Old Rates]]

====== Target Materials ======
The following materials are available
<columns 100% lt 10% ->

  * NiFe
  * Co
  * Al<sub>2</sub>O<sub>3</sub>
  * Al
  * Nb
  * Cr
   

<newcolumn lt>  

  * Py
  * Cu
  * Mo
  * Fe
  * Ag
  * Ni

</columns>
====== Tech stuff ======
  * Outer chamber circumference: 150cm
  * Chamber radius: 23cm
  * CF100KE standoff: 8cm
  * CF100KE-center: 31cm
  * Max in-chamber source length (8.9cm diameter source cover): 23-10.74=12.26cm
  * Max source length: 20.26cm
  * Safe KE-target source length: 16.26cm

  * Target diameter 3x 2 inch, 1x 1.5 inch
  * Target thickness 2-3mm

====== Miscellaneous ======
  * The digital log sheet: {{wiki:uhvlogfile.doc}}
  * The digital maintenance sheet: {{wiki:uhvmaintenance.doc}}