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Thermal Evaporator

CHA-600
CHA Industries


Contact Information:
  Faculty Contact:   Aaron Hawkins
  Staff Contact:   Jim Fraser
  Student Contacts:   Sadek Sabbah

Maintenance Request for Thermal Evaporator


SCHEDULER IS REQUIRED

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  1. General Information

    1. The thermal evaporator uses resistive energy to evaporate thin films onto a given substrate. It can deposit materials with a specified thickness of up to 1500 nanometers. The thickness is controlled by the use of a quartz crystal monitor. Evaporants used in the BYU lab include silver, gold, aluminum, nickel, and chromium. Eighteen wafers can be processed simultaneously. Up to three different layers may be evaporated in one run.
  2. Equipment Specifications

    1. Power Supply: 3500 W
    2. Cryopump: Pressure of 10-8 Torr
    3. Sources: 3 in parallel individually selectable.
    4. Substrate Heat Control: 0 - 540 Degrees Celsius
    5. Measurements: 43"x84"x35" (Width x Height x Depth)
    6. External Tube Diameter: 20"
  3. Processes and Deposition Data

    1. Aluminum (Al)
      1. New boat:
        1. Slowly ramp current (50 Amps/min) up to 200 Amps.
        2. Wait (patiently) until samples are molten.
        3. Slowly increase current until the deposition rate is nonzero.
        4. More rapidly increase deposition rate to 10 Å/s.
        5. Maintain this deposition rate until you have reached desired thickness or sample is depleted.
        6. Slowly ramp current down (50 Amps/min) to zero.
      2. Used boat:
        1. Slowly ramp current (50 Amps/min) up to 250 Amps.
        2. Wait 15 min.
        3. Increase current to 300.
        4. Wait (patiently) until samples are molten. Depending on the condition of the boat, you may need to increase the current above 300 to get the aluminum to melt.
        5. Slowly increase current until the deposition rate is nonzero.
        6. More rapidly increase deposition rate to 10 Å/s.
        7. Maintain this deposition rate until you have reached desired thickness or sample is depleted.
        8. Slowly ramp current down (50 Amps/min) to zero.
      3. Notes:
        1. If you ramp too quickly, you’ll break the boats. If you vent the chamber too quickly, you’ll break the boats.
        2. If you are doing multiple depositions, you do not need to let the chamber cool down between depositions.
        3. Aluminum alloys with the tungsten boats, so you won’t be able to evaporate your entire sample. Don’t be afraid to ramp up the current (slowly) and try to evaporate as much as possible, but don’t go above 400 Amps. You’ll blow a fuse.
      4. Pressure should be in 10-6 range.
      5. Maximum deposited from one boat: 6200 Å.
      6. Ideal deposition rate: 10 Å/s.
      7. Number of aluminum pellets on boat not to exceed three.
      8. Ideal “warm up current”: 200 Amps.
      9. Program number on deposition meter: 1.
    2. Chromium (Cr)
      1. Ramp current up slowly (50 Amps/s) to 80 Amps.
      2. Let rod warm to a healthy glow.
      3. Increase current slowly until the deposition rate is nonzero.
      4. Increase current to obtain desired deposition rate.
      5. Notes
        1. Data based on use of chromium on tungsten rod.
        2. Rods tend to break if current ramped too quickly, particularly when ramping down.
        3. Chrome sublimes.
      6. High deposition rates are possible, but current tends to max out around 120 Amps. Further increases in current do little good and may cause additional strain on rod??
      7. Ideal “warm up current”: 80 Amps.
      8. Maximum thickness with one rod: ----
      9. Ideal deposition rate: ~30 Å/s.
      10. Pressure should be in 10-6 range.
      11. Program number on deposition meter: 2.
    3. Nickle (Ni)
    4. Gold (Au)
    5. Other materials
  4. Quick Materials Evaporation Reference

    1. Quick reference for materials common to IML lab.
    2. Metal Cr Au Ni Cu Al
      Density 7.2 19.3 8.91 8.93 2.7
      Z-Ratio 0.305 0.381 0.331 0.437 1.08
      Current (A) 80 190 185 190 200
      Dep. Prog.# 2 3 - - 1


    3. Table of density and Z-ratio values
      1. Material Symbol
        Melting Temperature (°C)
        Density (bulk, g/cm3)
        Z-Ratio
        Aluminum Al
        660
        2.70
        1.08
        Antimony Sb
        631
        6.62
        0.768
        Arsenic As
        612
        5.73
        0.966
        Barium Ba
        729
        3.5
        2.1
        Beryllium Be
        1287
        1.85
        0.543
        Bismuth Bi
        271
        9.78
        0.79
        Boron B
        2067
        2.535
        0.389
        Cadmium Cd
        321
        8.65
        0.682
        Cadmium sulfide CdS
        1750
        4.83
        1.02
        Cadmium telluride CdTe
        1041
        6.20
        0.980
        Calcium Ca
        839
        1.55
        2.62
        Calcium fluoride CaF2
        1360
        3.18
        0.775
        Carbon (diamond) C
        3550
        3.52
        0.22
        Carbon (graphite) C
        3652
        2.25
        3.26
        Chromium Cr
        1857
        7.20
        0.305
        Cobalt Co
        1495
        8.71
        0.343
        Copper Cu
        1083
        8.93
        0.437
        Copper(I) Sulfide (Alpha) Cu2S
        1100
        5.6
        0.69
        Copper(I) Sulfide (Beta) Cu2S
        1100
        5.8
        0.67
        Copper(II) Sulfide CuS
        1100
        4.6
        0.82
        Gallium Ga
        30
        5.93
        0.593
        Gallium arsenide GaAs
        1238
        5.31
        1.59
        Germanium Ge
        937
        5.4
        0.516
        Gold Au
        1063
        19.3
        0.381
        Gold Germanide AuGe(12%)
        -
        17.63
        0.3972
        Indium In
        157
        7.24
        0.841
        Indium antimonide InSb
        535
        5.76
        0.769
        Indium tinide InSn(80-20wt%)
        -
        7.25
        0.8176
        Iridium Ir
        2434
        22.4
        0.129
        Iron Fe
        1536
        7.86
        0.349
        Lead Pb
        327
        11.342
        1.13
        Lead sulfide PbS
        1114
        7.50
        0.566
        Lithium Li
        181
        0.534
        5.9
        Lithium fluoride LiF
        896
        2.64
        0.774
        Magnesium Mg
        649
        1.74
        1.61
        Magnesium oxide MgO
        2642
        3.58
        0.411
        Manganese Mn
        1244
        7.44
        0.377
        Manganese Sulfide MnS
        -
        3.99
        0.94
        Material Symbol
        Melting Temperature (°C)
        Density (bulk, g/cm3)
        Z-Ratio
        Mercury Hg
        -39
        13.6
        0.74
        Molybdenum Mo
        2617
        10.2
        0.257
        Nickel Ni
        1453
        8.85
        0.331
        Nickel chromide NiCr(80-20wt%) -
        8.52
        0.3258
        Niobium Nb
        2467
        8.57
        0.493
        Palladium Pd
        1552
        12.16
        0.357
        Platinum Pt
        1770
        21.37
        0.245
        Potassium chloride KCl
        770
        1.98
        2.05
        Selenium Se
        221
        4.82
        0.864
        Silicon Si
        1412
        2.34
        0.712
        Silicon dioxide (fused quartz) SiO2
        1610
        2.20
        1.07
        Silicon monoxide SiO
        1702
        2.13
        0.87
        Silver Ag
        961
        10.492
        0.529
        Silver bromide AgBr
        432
        6.47
        1.18
        Silver chloride AgCl
        455
        5.56
        1.32
        Sodium Na
        98
        0.971
        4.8
        Sodium chloride NaCl
        800
        2.17
        1.57
        Sulfur S8
        115
        2.07
        2.29
        Tantalum Ta
        2977
        16.6
        0.262
        Tellurium Te
        450
        6.25
        0.900
        Tin Sn
        232
        7.30
        0.724
        Titanium Ti
        1670
        4.50
        0.628
        Titanium oxide TiO
        -
        4.9
        N/A
        Titanium dioxide TiO2
        1825
        4.26
        0.40
        Tungsten W
        3380
        19.3
        0.163
        Tungsten carbide W2C
        2860
        15.6
        0.151
        Uranium U
        1132
        18.7
        0.238
        Vanadium V
        1902
        5.87
        0.530
        Ytterbium Yb
        824
        6.96
        1.13
        Yttrium Y
        1526
        4.48
        0.835
        Zinc Zn
        420
        7.14
        0.514
        Zinc oxide ZnO
        1975
        5.61
        0.556
        Zinc selenide ZnSe
        1100
        5.42
        0.722
        Zinc sulfide ZnS
        1700
        4.10
        0.775
        Zirconium Zr
        1852
        6.53
        0.60
        Material Symbol
        Melting Temperature (°C)
        Density (bulk, g/cm3)
        Z-Ratio
  5. Operational instructions for using the thermal evaporator

    1. Turn on necessary equipment in the back
      1. Turn on Nitrogen
        1. N2 On: N2 off:
      2. Turn on vacuum.
    2. Start up evaporator, program deposition meter
      1. Turn on power supply
      2. Turn on water flow
        1. Flow is off in image.
      3. On deposition meter, select preprogrammed option OR
        1. Press program to enter programming mode
          1. Display should change to that shown here
        2. Press enter ([E]) until selector bar is over large number on left titled film
        3. Enter desired program number according to this chart
        4. Press program to exit programming mode
      4. Program deposition meter
        1. Press program
          1. Display should change to that shown here
        2. Set stop thickness. Press enter until density slot is selected.
        3. Set density. Press Enter.
        4. Set Z-value Press Enter.
        5. Tooling factor should be ---%. If so, Press program, you’re done.
        6. See Video of deposition meter being programmed
        7. Partial List of common material properties
        8. Extensive list of material parameters available in XTM/2 Deposition Monitor Operating Manual
    3. Open bell jar and load wafers and targets
      1. Flip function selector switch from “OFF” to “Manual” Caution both vacs must be shut!
      2. Flip nitrogen vent switch until bell jar vents (you will hear and feel nitrogen escaping). Close nitrogen.
        1. need to take picture.
      3. Flip function selector switch to “OFF”
        1. This step prevents accidental opening of the vacuum valves.
      4. Flip raise bell jar switch. There will be a 10s delay and the jar will then open. When jar is completely raised, flip switch back to middle position.
      5. Insert wafers: Wafers snap into place. Replace glass slides with new clean ones. Close shutter.
        1. shutter operation
      6. select electrode ( front middle back). Load targets.
        1. Types of targets: boats and rods
      7. Establish orbiter’s rotation speed.
        1. Slider switch in middle position turns orbital on.
        2. Use speed dial to adjust rotational speed.
        3. Look inside to top of bell jar to gauge speed.
        4. Turn off orbital before lowering bell jar.
    4. Close bell jar and pump down the chamber
      1. Flip bell jar switch down. As before there is a 10 second delay before the jar begins to lower.
      2. Pay attention as jar lowers. It sometimes hangs up on the orbital structure. If it makes contact with the orbitals, flip the switch back up immediately; raise the jar & retry.
      3. Open rough pump
      4. Flip switch to manual
      5. Open roughing switch.
      6. Turn on thermogauge power. Wait until pressure drops to .5 torr.
      7. See Pictures for above instructions
      8. Initiate cyropump.
        1. Turn off roughing pump. Make sure switch is all the way closed (i.e. hissing sound had stopped) before flipping up the high vac switch.
          1. The pressure needle should bury left.
        2. flip ionization gauge gauge to 10-4 range
        3. Turn on filament power. Turn on degas & wait 5 mins. If the selector switch is above 10-4, the filament will turn off and you won’t get any pressure readings.
        4. Turn off degas. When gauge gets to 2 range, flip selector to 10-5. repeat for 10-6. you may have to wait 30-60 mins for the pump to get down past 4x10-6
    5. Begin Evaporation
      1. Turn on heater power. Make sure selector switch is on 100amps (bottom numbers)
      2. Rotate current dial slowly increasing current.
      3. If you approach 80 amps, flip the selector switch from 100 to 500.
      4. The amount of current required varies for diferent metals. This link describes specific process recipies.
      5. When you begin to get a deposition, press open shutter on deposition meter and open shutter inside bell jar by flipping shutter switch down.
        1. Dep meter gives timer + thickness
      6. Adjust current up or down to maintain ideal deposition rate for specific metal.
      7. At desired thickness, close shutter.
      8. Slowly ramp down current when finished.
    6. Open bell jar
      1. Turn off high vac switch (see step 5)
      2. Wait 10 mins for everything to cool down.
      3. Follow remaining steps in 3b.
    7. Turn off Equipment
      1. In the Back
        1. Turn off vac
        2. Turn off nitrogen (if no one else is using it.)
        3. For pictures see step 1.
      2. Open rough vac briefly to seal shamber
      3. Make sure heater power is off, gauge power is off
      4. Turn off main power breaker
  6. Troubleshooting

    1. Main power switch fails to start machine
      1. Breakers behind evaporator may be off
    2. Heater power switch indicator light fails to come on.
      1. Wiggle the selector switch. It's finicky.
      2. Fuses have failed. Contact Mark Louther or Jeff Campbell.
    3. Chamber won’t pump down
      1. Check ion gauge selector switch; it should start at 10-4
      2. Chech filament power. If selector switch is too high, it will turn off
    4. Boats Break Continually
      1. Things we know put additional strain on boats:
          1. Changing current too rapidly.
          2. Insufficient cool down time before vent.
          3. High currents. We've also seen high currents evaporate Al/W alloy (black in color) once all Al is evaporated.
      2. If you are aware of any tips for prolonging boat life, please pass them on.
    5. Chamber pumps down slowly - time to regenerate the cryropump.
      1. The cryopump periodically needs to be regenerated. This is caused by the pump "filling up". Careless mistakes, such as forgetting to close the high-vacuum valve before venting can make a regeneration necessary. There are three different things that let you know if a regeneration is necessary:
          (1) Most obvious is if the cryopump pressure gauge (locate to the right of the bell jar pressure gauge) reads anything greater than zero.
          (2) If the cryopump temperature becomes greater than 29 K or so.
          (3) If the thermal is not pumping down very well or has a poor base pressure (>4E-6 Torr). The cryopump temperature readout is not always accurate. Do not use it only to determine the need for regeneration. If you are sure the cryopump needs regeneration report it to lab administrator.

For more information on thermal evaporation, see our Metal Deposition page.

Comments or suggestions? Submit them to Brett Hansen.

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