Thermal Evaporator

CHA-600
CHA Industries

Contact Information:
Faculty Contact: Aaron Hawkins
Staff Contact: Jim Fraser
Student Contacts: Matt Hamblin

Maintenance Request for Thermal Evaporator

SCHEDULER IS REQUIRED

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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.
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"
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

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
1. Start up evaporator, program deposition meter
  1. The nitrogen and vacuum should be on at all times.
  2. Turn on power supply
  3. Make sure the chiller is on.
  4. On deposition meter, select preprogrammed option OR
    1. Press program to enter programming mode
      2. 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
  5. Program deposition meter
    1. Press program
      2. 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
2. 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.
    2. 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.
3. 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.
      2. 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
4. 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.
    2. 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.
5. 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.
6. 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
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:
  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: