A blog on the repair, operation and calibration of surface analysis systems and components including electron spectrometers, sputter ion guns and vacuum related hardware. Click on the Index tab below to see a list of all posts. Visit our website at http://www.rbdinstruments.com
Why do you need sputter rate standards anyway? Each ion source will produce a different sputter rate depending on the conditions that the ion source is operated at, as well as other factors such as the angle of the ion source to the sample. Changing the beam voltage, condenser and focus (beam size), pressure (amount of argon or other gas) and raster area all affect the sputter rate. By using a sputter rate standard you can characterize your ion source for a particular set of operating conditions for a known oxide layer thickness of standard material (Ta2O5 or SiO2).
To further complicate things, the sputter rate of different materials varies greatly and that makes it very difficult to accurately know the true sputter rate for compounds and multi layer samples.
The link to this SPECs article for some very helpful insights into sputter rates on different materials:
And, here is a link to a PNNL publication on the sputter rates of oxide films relative to SiO2.
TaO5 sputter rate standard
RBD Instruments provides a 1000 Angstrom oxide layer TaO5 sputter rate standard which is approximately .75 X .50 inch in size. Both sides of the standard can be used, so one standard can last a long time. The RBD part number is TA2O5RE.
SiO2 sputter rate standard
RBD Instruments provides a 1000 Angstrom oxide layer SiO2 sputter rate standard which is approximately .50 X .50 inch in size and comes in a two pack. The RBD part number is SIO2CALRE and like the TaO5 standard, both sides can be used.
To request a quote for either standard, contact RBD here or go to the upper right hand corner of the RBD Instruments website and create a sales ticket. (www.rbdinstruments.com)
This procedure describes how to replace the solenoids in the Auto Valve Controller (AVC) used on Physical Electronics PHI surface analysis systems such as XPS Photo-electron and scanning Auger electron spectrometers.
The AVC provides control of the pneumatic valves on the system by using 24V DC solenoids to route air to either open or close the valves as needed. The symptom for a failed solenoid valve is that the light on the AVC remote box indicates that the valve is open, but the actual valve does not open. Or, it may be that the valve will not close.
The function of each valve is listed below:
Gate valve – Isolates load lock from main vacuum chamber
Vent valve – Isolates nitrogen back-fill from load lock
Isolation valve – Isolates turbo pump from load lock
Differential pumping valve – Isolates turbo pump from ion gun
Vent valve – Isolates nitrogen from turbo pump
Pre-pump valve – Isolates mechanical pump from load lock
There are two ways to test the solenoids;
1. Remove the air line (s) to the suspect pneumatic valve and open/close the valve manually. Some valves have two air lines and some have only one. In the case of two air line valves (typically V1 and V4) air should come out of the top air line to the valve when closed, and the bottom airline on the valve when open. If the AVC remote box indicates that the valve is changing states but the air does not change, then the solenoid is most likely bad.
2. You can remove the P10 cable plug from the back of the AVC measure the 24V DC voltage between the pins for the valve in question as shown in the table below. When ON, you will have 24V DC between the two pins for the solenoid in question.
Before you remove the P10 cable you need to close all valves on the AVC remote (V1, V2, V3 and V4) and turn off the turbo pump (s). Also turn off the air to the AVC manifold on the back of the electronic or vacuum console. Usually the air is connected to the console with a quick connect fitting. See Important Notes before turning off the air.
AVC solenoid wire connector info
When a solenoid is not working properly it is possible and even likely that the vacuum chamber can come up to air during the solenoid replacement procedure.
It is recommended that all valves be closed and the turbo pump(s) turned off before proceeding with the replacement of a solenoid. Note that even though the AVC remote may indicate that a valve is closed, if the solenoid is defective the valve may not actually be closed.
In addition to turning off the turbo pumps, also turn off the card rack power, all electronics, the ion gauge and the ion pump control.
Finally, before proceeding with the replacement of a solenoid, unplug or turn off the air to the back of the vacuum console. Most valves will hold their state (closed) with no air supplied to the valve, but marginal valves may leak when the air is shut off.
Solenoid replacement procedure:
Close all valves on the AVC
Turn off the turbo pump(s)
Turn off the ion gun, electron gun and X-ray source controllers
Turn off the card rack power
Turn off the DIGIII ion gauge control
Turn off the Boostivac ion pump controller
Turn off the AVC main power
Turn off or unplug the air to the back of the console
Unscrew the front panel AVC screws and slide out the AVC controller a little bit
Unscrew the air manifold screws so that you can access the solenoid screws
Unscrew the solenoid that you want to replace. The V1 solenoid is a little bit higher than the other ones and it is located at one end of the air manifold. Starting with the V1 solenoid, the order is V1, V2, V3, V4, V5 and V6.
Cut the wires to the existing solenoid. Make sure that you have enough length for when you reconnect the wires to the new solenoid. Note that the V1 solenoid has 2 sets of wires, upper coil and lower coil. Make sure that you keep the upper coil label on the wires so that you can connect the new solenoid upper coil wires to the correct set.
Cut the wires on the new solenoid to length and strip the ends on the wires that went to the old solenoid and also on the ends of the new solenoid.
Connect the wires together. White to white, black to black (except for V2 which has a yellow wire). You can use twist connects, in line crimp connectors or solder and heat shrink.
Screw the new solenoid into the manifold. Make sure that the black seals on the solenoid line up with the holes in the manifold. Snug the solenoid down firmly but do not over tighten the screws as the manifold is aluminum and it is easy to strip the manifold.
Use tie wraps to tidy up all the wires
Reattach the air manifold to the AVC controller
Make sure that all of the wires on the back of the AVC controller are still connected properly.
Use the front panel screws to reattach the AVC controller to the console.
Turn on the AVC controller main power. All valves on the AVC remote should indicate closed.
Reconnect the air to the back of the console.
Next, see if the ion pump control starts and stays on in the Run mode. If so, the system is still under vacuum.
Turn on the DIGIII ion gauge control and press the I/T 3 button to turn on the ion gauge.
If the ion pumps started and the ion gauge turned on, you should be back in business and can turn on the turbo pump (s) and use the system as you would normally.
If the ion pump control does not start then the system is up to air or partiality up to air. To test the condition of the vacuum inside the chamber, you can pump on the load lock until you have 5 bars and them manually close V3 and manually open and immediately close V1. That will equalize the vacuum in the load lock with the chamber. Now check how many bars you have on the AVC remote box. If 3 or 4 bars then the chamber is only partial up to air and you can just open V3 and V1 and rough the chamber out for 10 to 15 minutes to get into the 10-6 Torr range and then start the ion pumps.Close V1 once the ion pumps start.
If you only have one bar, then the chamber is likely up to air and you should bring the chamber up all the way by back filling with Nitrogen and then pumping the chamber back down. Those procedures are detailed at the bottom of this blog post.
If you have a leaking solenoid and need a replacement, RBD Instruments provides them and our part numbers are listed below. Please contact us for a quotation.
RBD AVC Solenoid part numbers
RBD part number
AVC solenoid designation
V1 24V Solenoid/Auto Valve Control
V2 24V Solenoid/Auto Valve Control
V3, V4, V5, V6 24V Solenoid/Auto Valve Control
V3, V4, V5, V6
If you need to bring the vacuum chamber all the way up to air, here is the procedure –
System up to air procedure
This procedure will allow you to safely bring the 660 scanning auger system up to air for maintenance.
Shut down all electron, ion and X-ray source power supplies.
Turn off the card rack power
If V4 is open, close it by pressing the Diff Pump Ion Gun button on the AVC remote.
Pump the intro. If you need
Turn off the DIGIII ion gauge.
Turn off the Ion pump control and Boostivac control.
Allow the system to cool for at least 30 minutes. (Or just a few minutes if the electron gun was not on.)
Make sure that the turbo pump is on. If you have more than one turbo pump, they both need to be on.
With the turbo pump on and the intro still being pumped, depress the Backfill Chamber button on the Auto Valve control located behind the vacuum console.
You will hear a hissing sound as air is back-filled into the chamber.
Slightly loosen the intro hatch cover so that when the system is pressurized it will open.
Once the system is vented, turn OFF the turbo pump(s).
System Pump Down procedure
This procedure will allow you to safely pump down the system after being up to air for maintenance.
Make sure that all flanges are secured (use new copper gaskets whenever removing and replacing optics on the vacuum chamber).
With the turbo pump(s) off, depress the Rough Chamber button on the Auto Valve control located behind the vacuum console.
Make sure that the intro hatch is closed.
Turn on the turbo pump(s) by depressing the pumping unit button. You will hear the V2 valve close and the V3 and V4 valves open and the turbo(s) will begin to pump the system out.
After about 20 minutes you should have 5 bars on the Auto Valve control remote. Once you have 5 bars, cycle each of the 4 titanium sublimation filaments for about 2 minutes each at 50 amps on the Boostivac control.
Cycle each filament 2 times, with a few minutes of cool down time between filaments.
After all 4 filaments have been out-gassed, make sure that you still have 5 bars on the Auto valve control remote and then turn on the DIGIII by turning the power switch to UHV and depressing the I/T 3 button.
The DIGIII should indicate in the low 10-3 to mid 10-4 range. Allow the turbo to pump until the system pressure is in the low 10-4 to high 10-5 range, about 30 additional minutes.
Cycle the #1 titanium sublimation filament for about 2 minutes at 50 amps. (Note: If a TSP filament can no longer get at least 45 amps, use the next filament).
When the vacuum is in the low 10-5 range, start the ion pump control by turning the Mode switch to Start. Monitor the 10KV scale. The voltage should be increasing (maximum is about 5.5 kV), and the DIGIII should indicate that the vacuum is dropping into the 10-6 range. (Note that the meter on the Boostivac does not always read, if not then just make sure that you are in the 10-6 range and dropping on the ion gauge).
Once the DIGIII indicates the high 10-6 range, close the V1 valve by depressing the Rough Chamber button on the Auto Valve control located behind the vacuum console one more time. You will hear the V1, V3 and V4 valves close.
On the Auto valve control remote, depress the Diff Pump Ion Gun button to differentially pump the ion gun.
The system vacuum will continue to improve over the next few hours. Cycle the #1 titanium sublimation filament every 30 to 45 minutes to help the ion pumps pull the vacuum down.
Once the base pressure is in the low 10-7 to mid 10-8 range, the system can be baked out to obtain the best possible base pressure.
The 20-610 high voltage gun supply used on PHI 600 and 660 scanning Auger systems provides the beam voltage, filament current and emission voltage to the Lab6 filament in the cylindrical mirror analyzer.
As part of the linearity adjustment process, the beam voltage is set to 3 keV so that the top of the elastic peak comes in at 3 keV.
The 3 keV elastic peak adjustment potentiometer in the 20-610 is R108. The process is simple:
Adjust the specimen stage Z axis for maximum counts and best shape of the peak during a 3 keV elastic peak alignment.
Adjust the analyzer control gain so that the AES peaks come in at the correct location in a survey. Typically clean copper is used since it has both low and high energy peaks.
Reacquire the elastic peak but do not move the specimen stage. If the elastic peak does not come it at 3 keV, move the elastic peak to 3 keV by adjusting R108 in the 20-610.
Sometimes there is not enough range of adjustment with the R108 potentiometer. For those cases, this blog post will explain how to modify the PCB 100 board in the 20-610 in order to extend the 3 kV adjustment range.
The schematic below shows the R108 potentiometer circuit.
The ends of R108 are connected to + and – 12V via two 49.9 K ohm resistors, R107 and R109. Adjusting R108 adds a small offset current to IC 103, which in turn changes the 3 kV output of the 20-610.
If there is not enough range with R108 then we need to change the balance between the + and – 12 volt supplies. The way to do that is to remove R107 and replace it with a 100 k ohm trim potentiometer that is set to an initial value of 49.9 K ohms. 100 K ohm trim pots are available from any electronic component vendor (Digikey, Newark, Mouser….)
To prep the 100 K ohm trim potentiometer, the center wiper connection needs to be soldered to either end as shown below.
With an ohmmeter, measure the resistance between the trim pot legs and adjust it for a resistance of 49.9 K ohms.
Turn off the 20-610 and on the back of the unit, unplug the main power cord, the remote program cable and the unscrew and remove the large HV cable connector. If there is a ground wire attached, remove it as well.
Place the 20-610 on a work bench and remove the 100 board. You will need to remove the board tie down bracket. Important! – Make sure that the 20-610 in unplugged when removing or installing the board tie down bracket as it is very close to some exposed wires that have voltage on them when the 20-610 is plugged in.
Unsolder R107 and install the new trim pot on the back side of the 100 board. You will need to bend the two pins on the trim pot so that the adjustment screw faces up.
Reinstall the 100 board inside the 20-610. Make sure that it is seated all the way into the mother board connector. Reinstall the board tie down bracket. Do not put the cover back on the 20-610.
Install the 20-610 into the electronics rack and reconnect the large HV cable (be sure to screw it in all the way), and the HV programming cable. Make sure that the 20-610 main power switch is OFF and then plug in the main power cord into the interlocked power strip.
Slide the 20-610 out enough so that you can get to R108 and the new trim pot. Make sure that the 20-610 main power is OFF.
Remove the filament cap from the analyzer (3 screws) and connect a DVM and high voltage probe to either of the filament tabs. The ground reference on the high voltage probe should be connected to the vacuum chamber.
***Caution, high voltage is present! Refer adjustment to qualified personnel ***
Turn on the 20-610 and using AugerMap and the normal turn on procedure, set the beam voltage to 3 kV.
***Caution, high voltage is present! Refer adjustment to qualified personnel ***
Center R108 and then adjust the new 100 K ohm trim pot so that the voltage on the filament cap is 3,000 volts.
Turn off the beam voltage in AugerMap and then turn off the 20-610.
Reconnect the filament cap to the analyzer. Press down on the cap as you tighten the 3 screws that hold the cap onto the top of the CMA filament adjustment housing.
Turn the 20-610 back on and turn the beam voltage on and set it to 3 kV. Bring up the filament current to the normal operating point (typically 1.3 amps)
Perform the AES calibration procedure and adjust R108 so that the elastic peak comes in at 3 keV. When you are finished with the AES calibration, put the cover back on the 20-610 (front 2 cover screws only) and slide it back into the console. The AES calibration procedure is listed below –
Auger energy calibration on 600 and 660 scanning Auger systems
This procedure requires sliding the 20-610 high voltage supply out and removing the cover to gain access to the beam voltage offset potentiometer, R108. Turn off the 20-610 when sliding it in out or in, and when removing or installing the cover.
Load a sample of pure copper.
If you are using AugerMap software, set the magnification to 10,000X and use the Area Scan mode to minimize sample topography effect on the Auger signal.
Perform an elastic peak alignment and adjust the Z axis sample position to obtain maximum counts and best peak shape.
Sputter the sample clean until no carbon or oxygen is present.
Re-acquire the elastic peak to ensure that the sample is at the optimum position: highest counts and best peak shape. When the elastic peak is differentiated, the positive and negative excursions should be equal and symmetrical.
From this point on, do not move the sample!
With the beam voltage at 3kV, acquire a survey from 30eV to 1030eV, using .5eV/step, 50 ms/point.
Differentiate the survey and check the peak positions against the correct values as listed in the PHI handbook or other reference. A typical value is 920eV for the high energy peak and 60eV for the low energy peak on copper.
Note: If using AugerScan software, you can simply adjust the scale factor in the AES
Acquire an alignment with a range of 900 to 940, .5eV/step, 15ms/point and do the adjustment in real time. For copper, set the n/e peak to approximately 917eV. When differentiated, the high energy Cu peak should be 920eV.
Acquire another survey and check that the differentiated peak positions are correct. Document the results for future reference and file it in the system calibration log.
Acquire another elastic peak, but do not move the sample!
If the elastic peak is not centered at 3kV, then adjust R108 in the Bertan 20-610 High Voltage power supply to center the elastic peak.
Calibration is complete.
From this point on, every-time you set the elastic peak, the sample will be at the focal point of the analyzer (maximum signal and best shaped peak), and all of the Auger peaks will be in the correct positions.