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
Category Archives: General Optics and Vacuum
General information on repair, maintenance, and operation of both PHI (Physical Electronics) and other manufacturers’ systems and components
If you try to start an ion pump when the vacuum in the chamber is in the mid 10-4 range, the gas load will be high enough to produce a visible ion plasma. Normally you don’t start the ion pumps until the vacuum is pulled down to the low 10-5 range by the turbo pump. But, sometimes you want to deliberately generate an ion plasma to help clean the ion pump elements.
Just start the ion pumps when the vacuum reaches the mid to low 10-4 Torr range. You may see that the pressure in the chamber rises to the 10-3 Torr range when the ion pump high voltage is turned on. That is OK; keep the ion pumps on while pumping the chamber with the turbo pump. You can leave them on for 5 minutes or so, then shut off the ion pump supply and let them cool down for 5 minutes. Then repeat the process. After a number of cycles, vacuum will be in the low 10-5 range and the ion pumps will start. You know when the ion pumps start because the vacuum goes into the 10-6 range and keeps improving slowly. By forcing the ion pumps to start in the high 10-4 range the resultant ion plasma helps to clean the ion pump elements.
If the pumps are loaded with argon or contaminated with hydrocarbons, you want to use oxygen to produce the ion plasma because oxygen will react with the contaminants. Assuming the ion pumps are started, back fill oxygen into the vacuum chamber to 5 X 10-5 Torr. Turn off the ion gauge and monitor the current on the ion pump control. Increase the oxygen until you get about 50mA of current on the ion pump control. Adjust the oxygen leak valve as needed to maintain 50mA or so of current. Maintain this condition for about 30 minutes, and then turn the oxygen off. As the pumps cool down the vacuum will recover and typically by the next day the ion pumps are happy once again.
For more info on ion pumps type Ion Pump Element rebuild procedure in the RBD TechSpot search box
This post is about how to adjust the 951-5100 and 951-5106 Varian variable leak valve commonly found on vacuum chambers across the globe. Invented in 1968 by William Wheeler and Paul Hait, the patent was assigned to Varian Associates; many thousands of these valves have been built since then. In 2010, Varian was purchased by Agilent Technologies and since that time it has been harder to find the rebuilt kits for these variable leak valves. The order information for the rebuild kit can be found at the bottom of this post, as well as a link to the instruction manual.
Varian variable leak valve
Overview-
When this type of variable leak valve does not close all the way, operators will usually unlock the two knurled knobs and move them up the fine drive screw assembly and then re-lock them. What that does is to allow the handle to move out further from the valve body and put more pressure on the sapphire, which effectively closes the valve. That works fine for periodic adjustments to close the valve. However, if the handle is far away from the valve body it is possible to get too much leverage and crack the sapphire (which causes catastrophic valve failure) and also reduces the range of the valve arm. The picture below shows a valve handle that is too far away from the valve body and needs to be reset.
Adjustment procedure –
When properly adjusted, the handle will be parallel to the valve body when closed. Gas should just start to leak into the vacuum chamber when the knob is turned CCW by 2 full turns. The following procedure is an abbreviated version that I use which works most of the time. For a more thorough explanation of this adjustment refer to the manual.
CAUTION! Read and understand the procedure and notes before you attempt the adjustment on your system. You need to know exactly how much gas pressure you are putting into the valve, how much you need to adjust the valve by and the status of your vacuum chamber. The roughing screw is very sensitive; a very small amount of adjustment can be the difference between success and a dumped system!
1. Use a small straight blade screwdriver to remove the hole cover on the back end of the leak valve to expose the roughing screw cap hex head.
2. Insert a 5/16” Allen wrench into the cap head of the roughing screw
3. Monitor the vacuum in the chamber. For most PHI surface analysis systems the vacuum should be in the low 10-9 Torr or lower. 4. If necessary, adjust the handle so that it is parallel to the valve body. The knobs will need to be adjusted – turn the top knob CCW while holding the bottom knob in place. That will separate the two knobs and then you can spin them one at a time into position. Lock them on the fine drive screw assembly by holding the bottom knob in place and turning the top knob CW until it firmly butts up against the bottom knob. There is a spring washer between the two knobs that helps to lock them together. Once set, always turn both knobs together when opening (turn CCW) or closing (turn CW) the valve.
NOTE: Keep an eye on the vacuum in the chamber as you SLOWLY adjust the handle. If the pressure starts to increase, turn the Allen wrench CW by a few degrees to close the valve. The roughing screw is coarse threaded and so a very small movement on the Allen wrench has a large effect on the valve, whether closing (CW) or opening (CCW). The maximum torque that should be applied to the roughing screw is 6 foot lbs.
5. Once the handle has been set so that it is parallel to the valve body and the valve is closed (no gas leaking into the chamber) you are ready to adjust the open position of the valve. 6.SLOWLY turn the knob (both knobs turn together) CCW while observing the vacuum in the chamber. You want to get to two full turns without bleeding any gas into the chamber. If you start to see leakage before two full turns on the valve, compensate by turning the Allen wrench CW slightly until the leakage stops and the vacuum starts to recover. 7. Once you have the valve open two full turns with no leakage, SLOWLY turn the Allen wrench CCW in increment of 1 to 2 degrees at a time until the gas just starts to leak into the vacuum chamber. Then close the leak valve by turning the knob fully CW (two turns). 8. Verify that the gas just starts to leak into the vacuum chamber at about 2 turns. If necessary, adjust the Allen wrench in very small increments. Sometimes it is not possible to have the valve open at two turns. It may not open until as many as 6 turns, and that is still acceptable. The idea is to have predictable, smooth and repeatable control. 9. When you close the valve, go just finger tight – do not over tighten the knob or you will damage the threads on the fine drive screw! The fine drive screw should be periodically lubricated, I prefer C5A over moly-disulfide.
NOTE: If you are adjusting the leak valve after connecting a pressurized gas bottle for the first time, have the Allen wrench inserted into the roughing screw so that you can quickly close the valve further if the pressure in the chamber rises. Sometimes a valve will seal fine in atmosphere but leak when up to 500 PSI is applied to the back end of the valve. The valve is rated for a maximum of 500 PSI inlet gas pressure, but it will work better with 100 PSI or less.
If this procedure does not work, then the valve may need to be cleaned or the sapphire and gasket assemblies replaced. There is a limited lifetime on the gasket assembly as the copper gasket becomes compressed with each use. The manual specifies anywhere from 20 to 300 valve closures based on whether or not the valve is baked out or not. However, on the surface analysis systems where I have seen these valves used, they can operate for many years with little or no adjustment.
Refer to the manual for cleaning and rebuild instructions as well as a more detailed adjustment procedure.
To place an order, the following information is required: Purchase order number or credit card, delivery date, ship to, invoice to, end user, and quote number. GSA customers please provide GSA contract #.
2) Call 1-800-882-7426 (option 1) any weekday between 8 am and 7 pm Eastern time, in the U.S., and Canada. You will need to know the purchase order or credit card number the order was placed on.
This document contains information about optics repair methods, procedures and tricks that are useful when working on older PHI optics units such as cylindrical mirror analyzers, x-ray photoelectron spectrometers and sputter ion sources.
General Optics Guidelines.
Clean all tools with isopropanol or methanol and also degauss them if possible. Most customers have degaussing coils which came with their system. If not, RBD can provide them.
Always use gloves when working with optics. This is to keep oils from your fingers from contaminating the optics.
Maximize space between all high voltage wires and ground to prevent arcing.
Avoid sharp points on all connections to prevent arcing.
When ever possible, cover all high voltage wires with ceramic tubing, ceramic beads or Teflon tubing. If you can’t do that, then make sure all HV wires have gentle bends and no sharp bends. Sharp bends, just like sharp points, can increase the chance of arcing.
Tighten all screws securely, especially if the unit needs to be shipped after a repair. Vibration from shipping can cause optics to loosen up and become damaged.
Degauss the analyzer several times during the re-assembly process, especially when the magnetic shields go back on.
Analyzers.
Single pass CMA (cylindrical mirror analyzer).
The PHI single pass CMA is the most common type of Auger (AES) analyzer in the surface analysis industry. It is a very simple and mostly reliable device. Double Pass CMAs are essentially two single pass CMAs stacked on top of each other to increase energy resolution which allows for the acquisition of X-ray Photoelectron spectroscopy (XPS, or ESCA) data.
To maintain optimum performance, analyzers need to be cleaned periodically. Depending on usage, vacuum conditions and amount of sputtering, this could be anywhere from 2 years to 20 years. Expendable items such as filaments, electron multipliers and grids need to be changed on more regular basis.
PHI CMAs that RBD services:
Model Number
Description
Specifications
Filament type
Multiplier type
10-150
TFA
100 uM beam size
C75010RP
4839RE
10-155
TFA
100 uM beam size
C75010RP
4839RE
15-110
Scanning
5uM beam size
C75010RP
4731GRE
15-110A
Scanning
3uM beam size
C75010RP
4731GRE
15-110B
Scanning
1uM beam size
C75010RP
4731GRE
15-255G
Double pass CMA
100uM beam size
C75010RP
4731GRE
25-110
Scanning
2000Ǻ beam size
LAB6590RE
4831GRE
25-120
Scanning
500Ǻ beam size
LAB6595RE
4831GRE
25-120A
Scanning
350Ǻ beam size
LAB6600RE
4831GRE
25-250
Double pass CMA
100uM beam size
C75010RP
4731GRE
25-260
Double pass CMA with Scanning
1uM beam size
C75010RP
4731GRE
25-270
Double pass CMA with Scanning
<1uM beam size
C75010RP
4731GRE
CMA analyzers have many things in common. For example, all CMAs have:
Inner cylinders with grids
Outer cylinders
Conical and flat terminating ceramics
Electron guns
Ceramic feed-throughs
High voltage insulating ceramics
Copper and tantalum wire
Coupling connectors
Set screws
Magnetic shields
General Analyzer Tips
Be very careful when removing and replacing the conical ceramic as it can chip and break easily. Replacements cost is $2K to $4K.
When replacing the conical ceramic, rotate it slightly. If the conical ceramic appears to be loose remove it and place some copper shims on the lip if the inner cylinder to ensure a solid electrical contact. If the conical ceramic does not make a good electrical contact, the background counts in the data will increase dramatically above 800 eV or so, resulting is poor data.
Ensure that all electron gun ceramics and lenses seat properly before tightening. This ensures that the electron gun will be co-axial with the center of the CMA. If the electron gun is not centered, it will be off-axis resulting in a poor elastic peak shape and low Auger signal.
Use tantalum wire for deflection leads. It is more flexible than copper and will last longer before it breaks.
Use .020″ copper wire or thicker for filament leads. .015″ wire will not provide sufficient current to the filament and you will not be able to get any emission from the filament.
Measure the resistive of the flat terminating ceramic and conical ceramic before you re-assemble the analyzer. Note the values so that you can determine if they are making proper electrical connection after the conical ceramic is replaced. Example: The flat ceramic is 4 M ohms and the conical ceramic is 1 M ohms. If the conical is not making contact, the resistance from the outer cylinder to ground will be 4 M ohms. If only the conical ceramic is making contact but the flat is not, the resistance from the outer cylinder to ground will be 1 M ohms. If they both are making good electrical contact, the resistance will be 750KW.
The outer cylinder is called VM (for voltage modulation) on most CMA analyzers. On double pass CMAs such as the 15-255G and 25-260/270, it is called OC (for outer cylinder).
VM and OC resistance checks.
Model Number
Resistance check
10-150
VM to ground = 3 to 3.2 M ohms
10-155
VM to ground = 3 to 3.2 M ohms
15-110
VM to ground = .6 to .8 M ohms
15-110A
VM to ground = .6 to .8 M ohms
15-110B
VM to ground = .6 to .8 M ohms
15-255G
IC to OC = .6 to .8 M ohms IC and OC to ground = open
25-110
VM to ground = 3 M ohms
25-120
VM to ground = 3 M ohms
25-120A
VM to ground = 3 M ohms
25-250, 25-260, 25-270
IC to OC = .6 to .8 M ohmsIC and OC to ground = open GR to ground = open
Tip: If measuring on a system, make sure that the electron gun is off or the electrons coming into the front of the analyzer will give you a false reading.
590 Filament Replacement Procedure
Remove the magnetic shield (4 screws).
Carefully remove the conical ceramic ring (4 flat head screws) and remove the conical ceramic.
Remove the outer cylinder (1 screw), careful not to force it. If necessary, use a heat gun to loosen it up.
Separate all of the wires in the bottom of the analyzer using 2 needle nose pliers or tweezers. Be careful not to stress the wires. Position the wires so that you can easily remember where the go back. In the case of the F1 and F2 wires, this is easy. For the DEFL/STIG wires, position the wires as upper right and upper left, lower right and lower left.
Loosen the 4 spline set screws on the top of the inner cylinder by 1 turn CCW.
Remove all but one of the eight screws around the middle of the inner cylinder.
Remove the upper inner cylinder grid cap (4 screws).
Holding on to the nose of the electron gun, remove the final screw at the middle of the inner cylinder.
Carefully pull the electron gun up and out of the inner cylinder. Be careful not to stress any of the wire connectors.
Place the electron gun on a sheet of aluminum foil.
Loosen the bottom cap of the electron gun (4 screws and 4 set screws)
Carefully slide the bottom cap down the ceramics for about 2”, enough room to get at the filament.
Remove the filament assembly (4 cap screws, 2 splines connecting the filament wires).
Install the new filament assembly, and reverse all of the above steps.
General tips:
Clean and demagnetize all of your tools.
Place all removed parts on a clean work area covered with Aluminum foil.
If possible, dust off all parts with nitrogen as you re-assemble them.
Never force any part that doesn’t want to go.
You can use methanol as a lubricate if screws don’t move easily.
15-110 Analyzer Burn-In Procedure (also for the 560 AND 570 ESCA analyzers)
First, bake system after installation. If that is not possible, bake out just the analyzer using heat tape. 200 degrees Celsius for 6 to 8 hours.
Allow the analyzer to cool down.
Set the beam voltage to 500 volts and the emission know fully CW. Slowly turn up the filament current on the 11-045 until you have .1 to .2 mA of emission current (about 6 to seven turns on the filament knob).
Very slowly, (over a period of 1 to 2 hours) bring the filament up to 2mA of emission current.
Next, slowly bring the beam voltage up to 2kV (about 30 minutes from 500 volts).
Set the condenser on the 11-045 to maximum and do an elastic peak alignment.
Slowly increase the multiplier voltage until a peak is just visible.
Leave the multiplier voltage at this setting for 6 hours or more.
After the multiplier burn-in procedure is complete, slowly increase the beam voltage to the normal setting.
Note: The higher you operate the beam voltage, the slower you need to out gas it. Typically, you can go from 2kV to 5kV in 2 or 3 hours. 5kV to 8kV takes an additional 4 to 6 hours. Once conditioned, you can go up to that beam voltage quickly.
15-255G Filament Change Procedure
Use gloves, de-magnetize all tools and clean all tools with Isopropanol.
Set analyzer on stand or use manuals and support analyzer on handles, facing up.
Remove outer magnetic shield (4 screws)
Remove inner magnetic shield (4 screws)
Carefully remove conical ceramic
Lift upper outer cylinder up and set aside on clean aluminum foil.
Carefully lift inner cylinder up and off of the electron gun assembly. Note: If the inner cylinder does not move freely, use a heat gun to expand the inner cylinder so that it will slide off. Do not force it! Be careful not to damage the grids.
Look at the 10-155 electron gun detail to familiarize yourself with the electron gun assembly. The 15-255G has basically the same electron gun as in the 10-155.
Remove the three long screws that hold the electron gun assembly together.
Remove the V1 emission screw
Remove the 2 filament couplers from the filament posts. You will need a .048 4 spline wrench.
Remove the 3 filament ceramics.
Remove the filament assembly. Note the orientation of the emission tab and filament posts.
Remove the 3 screws that hold the filament base on and remove the filament.
Install the new filament in the same orientation as the old filament into the emission cap.
Install the 3 screws and the filament base and tighten slightly.
Position the filament so that it is centered in the hole and tighten the 3 screws. This is best done using a microscope.
Install the filament assembly on top of the 3 filament ceramics and use the 3 long screws to hold the assembly together. The three long screws need to be tightened firmly so that they all have the same distance with respect to the base.
Reconnect the V1 wire
Reconnect the filament couplers.
Ohm out the connections to the filament and V1.
Degauss the gun assembly.
Install the inner cylinder over the electron gun assembly.
Reinstall the upper outer cylinder.
Carefully install the conical ceramic. The resistor part should be 180 degrees out from the center flat ceramic. Ohm out VM to ground and make sure it has the correct resistance. See the Conical Ceramic PDF file for more information.
Install the inner magnetic shield
Degauss the analyzer.
Install the outer magnetic shield.
Degauss the analyzer. Installation complete.
SCA (Spherical Capacitive Analyzer)
10-360 SCA resistance and capacitance tests
Turn off the card rack power before proceeding.
SCA HV connector-
Remove the large SCA filter box (that has the big black cable going into it) and check for the following resistances –
Pin 1 to 3 = 7.4 Meg ohms
Pin 1 to 2 = 4.5 Meg ohms
Pin 2 to 3 = 2.9 Meg ohms
All SCA HV pins should be open to ground
Remove the POS and NEG filter boxes.
POS to NEG on the SCA should be about 15 meg ohms.
Capacitance tests –
POS to chamber should be about 850 pF (.850 nF)
NEG to chamber should be about 200 pF (.200 nF)
MCD connector
All pins should be about 300 pF (.300 nF) from the pins to the chamber, except for the 4 center pins which should be about 100 pF (.100 nF).
All MCD pins should be open to the chamber.
The PHI model 10-360 SCA analyzer is uses a different approach than the CMA which results in a higher transmission (better collection of signal). Since there are no grids in the SCA, the only maintenance normally required is the replacement of the electron multiplier.
There are three types of detectors used in the SCA. They are, single channel multiplier, PSD (position sensitive detector) and MCD (multi channel detector).
10-360 Detector and multiplier cross reference:
System Model
Description
Specifications
Detector Type
Multiplier type
5100
Large Area
2 X 10mm
Single channel
Channeltron
5300
Large Area
2 X 4mm
Single channel
Channeltron
5400
Small Spot
200uM
PSD
Channel plates
5500
XPS/AES
75uM
MCD
Chevron
5600
XPS/Scanning AES
30uM
MCD
Chevron
Ion Guns.
Hot Filament type
The most common type of ion gun is the hot filament type. A filament is heated up white hot and electrons are accelerated into the ionizer grid assembly. Argon gas is either injected or back-filled into the ionizer grid where electron impact converts the Argon atoms into Argon ions which are then accelerated towards the target.
Hot Filament Ion Guns have many things in common including:
