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CHA-600 CHA Industries |
Contact Information: Faculty Contact: Aaron Hawkins Staff Contact: Jim Fraser Student Contacts: Matt Hamblin |
General Information
- 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.
Equipment Specifications
- Power Supply: 3500 W
- Cryopump: Pressure of 10-8 Torr
- Sources: 3 in parallel individually selectable.
- Substrate Heat Control: 0 - 540 Degrees Celsius
- Measurements: 43"x84"x35" (Width x Height x Depth)
- External Tube Diameter: 20"
Processes and Deposition Data
- Aluminum (Al)
- New boat:
- Slowly ramp current (50 Amps/min) up to 200 Amps.
- Wait (patiently) until samples are molten.
- Slowly increase current until the deposition rate is nonzero.
- More rapidly increase deposition rate to 10 Å/s.
- Maintain this deposition rate until you have reached desired thickness or sample is depleted.
- Slowly ramp current down (50 Amps/min) to zero.
- Used boat:
- Slowly ramp current (50 Amps/min) up to 250 Amps.
- Wait 15 min.
- Increase current to 300.
- 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.
- Slowly increase current until the deposition rate is nonzero.
- More rapidly increase deposition rate to 10 Å/s.
- Maintain this deposition rate until you have reached desired thickness or sample is depleted.
- Slowly ramp current down (50 Amps/min) to zero.
- Notes:
- If you ramp too quickly, you'll break the boats. If you vent the chamber too quickly, you'll break the boats.
- If you are doing multiple depositions, you do not need to let the chamber cool down between depositions.
- 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.
- Pressure should be in 10-6 range.
- Maximum deposited from one boat: 6200 Å.
- Ideal deposition rate: 10 Å/s.
- Number of aluminum pellets on boat not to exceed three.
- Ideal "warm up current": 200 Amps.
- Program number on deposition meter: 1.
- New boat:
- Chromium (Cr)
- Ramp current up slowly (50 Amps/s) to 80 Amps.
- Let rod warm to a healthy glow.
- Increase current slowly until the deposition rate is nonzero.
- Increase current to obtain desired deposition rate.
- Notes
- Data based on use of chromium on tungsten rod.
- Rods tend to break if current ramped too quickly, particularly when ramping down.
- Chrome sublimes.
- 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??
- Ideal "warm up current": 80 Amps.
- Maximum thickness with one rod: ----
- Ideal deposition rate: ~30 Å/s.
- Pressure should be in 10-6 range.
- Program number on deposition meter: 2.
- Nickel (Ni)
- Gold (Au)
- Other materials
Quick Materials Evaporation Reference
- Quick reference for materials common to IML lab.
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 - Table of density and Z-ratio values
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
Operational instructions for using the thermal evaporator
- Start up evaporator, program deposition meter
- The nitrogen and vacuum should be on at all times.
- Turn on power supply
- Make sure the chiller is on.
- On deposition meter, select preprogrammed option OR
- Press program to enter programming mode
- Display should change to that shown here
- Press enter ([E]) until selector bar is over large number on left titled film
- Enter desired program number according to this chart
- Press program to exit programming mode
- Press program to enter programming mode
- Program deposition meter
- Press program
- Display should change to that shown here
- Set stop thickness. Press enter until density slot is selected.
- Set density. Press Enter.
- Set Z-value Press Enter.
- Tooling factor should be ---%. If so, Press program, you're done.
- See Video of deposition meter being programmed
- Partial List of common material properties
- Extensive list of material parameters available in XTM/2 Deposition Monitor Operating Manual
- Press program
- Open bell jar and load wafers and targets
- Flip function selector switch from "OFF" to "Manual" Caution both vacs must be shut!
- Flip nitrogen vent switch until bell jar vents (you will hear and feel nitrogen escaping). Close nitrogen.
- need to take picture.
- Flip function selector switch to "OFF"
- This step prevents accidental opening of the vacuum valves.
- 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.
- Insert wafers: Wafers snap into place. Replace glass slides with new clean ones. Close shutter.
- select electrode ( front middle back). Load targets.
- Establish orbiter's rotation speed.
- Slider switch in middle position turns orbital on.
- Use speed dial to adjust rotational speed.
- Look inside to top of bell jar to gauge speed.
- Turn off orbital before lowering bell jar.
- Flip function selector switch from "OFF" to "Manual" Caution both vacs must be shut!
- Close bell jar and pump down the chamber
- Flip bell jar switch down. As before there is a 10 second delay before the jar begins to lower.
- 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.
- Open rough pump
- Flip switch to manual
- Open roughing switch.
- Turn on thermogauge power. Wait until pressure drops to .5 torr.
- See Pictures for above instructions
- Initiate cyropump.
- 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.
- The pressure needle should bury left.
- flip ionization gauge gauge to 10-4 range
- 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.
- 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
- 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.
- Flip bell jar switch down. As before there is a 10 second delay before the jar begins to lower.
- Begin Evaporation
- Turn on heater power. Make sure selector switch is on 100amps (bottom numbers)
- Rotate current dial slowly increasing current.
- If you approach 80 amps, flip the selector switch from 100 to 500.
- The amount of current required varies for diferent metals. This link describes specific process recipies.
- When you begin to get a deposition, press open shutter on deposition meter and open shutter inside bell jar by flipping shutter switch down.
- Dep meter gives timer + thickness
- Adjust current up or down to maintain ideal deposition rate for specific metal.
- At desired thickness, close shutter.
- Slowly ramp down current when finished.
- Turn on heater power. Make sure selector switch is on 100amps (bottom numbers)
- Open bell jar
- Turn off high vac switch (see step 5)
- Wait 10 mins for everything to cool down.
- Follow remaining steps in 3b.
- Turn off Equipment
- In the Back
- Turn off vac
- Turn off nitrogen (if no one else is using it.)
- For pictures see step 1.
- Open rough vac briefly to seal shamber
- Make sure heater power is off, gauge power is off
- Turn off main power breaker
- In the Back
Troubleshooting
- Main power switch fails to start machine
- Breakers behind evaporator may be off
- Heater power switch indicator light fails to come on.
- Wiggle the selector switch. It's finicky.
- Fuses have failed. Contact Mark Louther or Jeff Campbell.
- Chamber won't pump down
- Check ion gauge selector switch; it should start at 10-4
- Chech filament power. If selector switch is too high, it will turn off
- Boats Break Continually
- 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.
- 1. Changing current too rapidly.
- If you are aware of any tips for prolonging boat life, please pass them on.
- Things we know put additional strain on boats:
- Chamber pumps down slowly - time to regenerate the cryropump.
- 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.
- (1) Most obvious is if the cryopump pressure gauge (locate to the right of the bell jar pressure gauge) reads anything greater than zero.
- 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:
For more information on thermal evaporation, see our Metal Deposition page.