ABREVIATED INSTRUCTIONS FOR WILDER E-BEAM DEPOSITION (Rm. 112)
POTENTIAL SERIOUS DANGERS TO YOU:
- GUN HIGH VOLTAGE: The ES-6 e-beam supply is 10,000 volts at up to 200mA. Stay clear--it's lethal. When the ES-6 supply is plugged in, never venture behind the evaporator, and especially,
DO NOT PUT YOUR HAND OR ANY OBJECT UNDER THE CHAMBER where the connections are made. The cables behind the unit are insulated and grounded, but nevertheless they also
should be avoided.
NEVER OPEN THE CHAMBER WHEN THE ES-6 IS PLUGGED IN;
high voltage lines are not insulated inside the chamber.
- ION GAUGE HIGH VOLTAGE: The ion gauge anode is also dangerous.
STAY CLEAR OF THE ION GAUGE AND CONNECTIONS when its supply (NRC 836) is on.
- Liquid Nitrogen: avoid frostbite, protect eyes.
POTENTIAL SERIOUS DANGERS TO THE EQUIPMENT:
- OIL: The diffusion pump oil will burn ("crack") if exposed to air (oxygen) when it is hot. Cleaning out and repairing the system after such an incident requires several messy days of labor. To avoid this,
NEVER ALLOW THE FORELINE PRESSURE (TC2) TO EXCEED 1000mT when the diffusion pump oil is hot. Following this rule will help avoid mistakes leading to cracked oil:
EVERY time you open or close a valve, think about the potential consequences on the foreline pressure, and MONITOR TC2. If you open a valve slowly and TC2 shoots off scale, quickly close it and you will probably save cracking the oil. Note, it is hard to keep the foreline pressure down when the cold trap is not cold. If closing the foreline valve causes an immediate rise to over 500mT, it may be because you need a liquid nitrogen fill.
If for some reason the mechanical pump dies on you, immediately close the foreline and main valves, turn off the diffusion pump, and make sure there is liquid nitrogen in the trap.
- FILAMENTS: The e-gun and ion gauge filaments will burn out in air (oxygen). They should not be exposed to pressures higher than 5x10^-4 torr. UNPLUG the ES-6 and TURN OFF the ION GAUGE SUPPLY BEFORE VENTING THE CHAMBER.
- BEAM POSITION off the source: If the ebeam hits the hearth, it can burn
a hole in it, possibly bursting water lines in the chamber and
cracking the pump oil. Keep power under 10% until you know the
beam is hitting the target. Continue to watch position as power is
increased, but never move beam position at high power.
COLD STARTUP
- Uncap water drain.
- Turn on yellow water valve until "click" is heard at black interlock flow sensor near water valve.
- Plug in mechanical pump and ensure belt does not slip and blue vent closed (no hiss)
- Check that roughing valve is closed, then open foreline valve.
- Verify that foreline pressure (TC2) is below 500mT.
- Turn on diffusion pump (switch on mech and diffusion pump breakers). It takes about 30 minutes to warm up; meanwhile you can load the chamber.
- Fill the cold trap (1 dewar) with liquid nitrogen after the diffusion pump has been on for 10 minutes.
LOADING CHAMBER, PUMPING DOWN, HEATING SUBSTRATE
- Verify that the main vacuum valve and roughing valve are closed.
- Watch TC2 as you slowly crack open the vent valve. It should not change.
- Open the vent valve to vent the chamber. Close valve when vented.
- Check to see that bell jar is free by moving it to the side a bit (bear hug)
- Hoist the bell jar (some hand pressure will keep the vibration down)
- Scrape and use vacuum cleaner on the chamber, starting at the top. Wear a dust mask to avoid inhaling metal particles.
- Clean and lightly regrease o-ring and mating surface.
- Load hearth with source material and mount substrate.
- Place thermocouple junction on top of substrate.
- Check placement of shutter and inficon crystal monitor head.
- Turn on inficon supply, verify crystal ok (t/x light does not
continue to flash); press the t/x button and check crystal life used
(center reading, %).
- Lower bell jar. Verify that substrate and TC are still in place through window.
- Rough out the chamber. Throughout this process, TC2 must not exceed 1000mT; if it does, close the roughing valve, open the foreline valve to remove the builtup pressure, then continue roughing out the chamber.
- Close foreline valve.
- Slowly open roughing valve; listen for mechanical pump load.
- Pump until chamber (TC1) is under 200mT.
-
When chamber is below 200mT (TC1), cross over to high vacuum mode:
- Close roughing valve.
- Open foreline valve.
- Watch TC2 while SLOWLY opening the main vacuum valve. The first 1 1/2 turns do nothing, then TC2 should rise slightly. If TC2 ever swings up wildly, close the main valve immediately to avoid burning the oil. Open the main valve entirely, keeping TC2 below 1000mT.
- When TC1 reads below 10mT, turn on variac heater switch. Slowly (over 2 minutes) bring the power up to desired level (e.g. about 60V for 150C). Monitor substrate temperature with TC (turn on DVM and cold junction).
- When TC1 reads essentially zero, turn on the ion gauge power, (DANGER high voltage at tube) put in 10^-4 torr range, and hold the start button for 1 second. On release, if reading is above half scale, turn off ion gauge to avoid burning out filament.
- Pump until ion gauge shows pressure in the 10^-6 torr range (typical is 3x10^-6).
INFICON CRYSTAL MONITOR SETUP
- keyboard: PROGRAM (light on), test: OFF, control: MANUAL.
- Press DENSITY, red STOP, enter density numbers, ENTER, STOP, z-factor numbers, ENTER.
- control:AUTO (important), test: ON, keyboard: LOCK (program light off).
- Press red STOP, white START, yellow ZERO. Verify rate=10/density.
- test: OFF, control: MANUAL (program light should be off, T/X should not blink)
E-BEAM DEPOSITION
WARNING--10,000 volts. Proceed only if trained. Stay clear of rear and underside of bell jar base.
NOTE: filament is on whenever power to ES6 is on. Always turn off HV breaker before venting chamber, or e-gun filament will burn out.
- Verify that inficon is programmed.
- With the chamber pressure below 1x10^-5 torr, plug in the high voltage supply.
- Turn on ES-6 main power breaker and keylock. All interlock lights should be on.
- Verify ES-6 gun 1 knobs are: emission current=0, beam position and dither each 8-10 o'clock.
- Verify shutter closed, substrate at desired temperature.
- Press red STOP on inficon supply, press red High Voltage ON on ES6 (DANGER: 10,000 Volts).
- Press white START and then ZERO on ifnicon supply.
- Use inficon remote "inc" to bring up emission current. The beam first turns on at about 8% power (center LEDs); it should then be just visible in the chamber and the gun 1 emission current meter should rise slightly.
li> Before increasing power further, verify that beam is hitting only the target source material. If "clicking" is heard from
ebeam supply, dither or position may be beyond capability of supply; do not run
in that condition.
- Slowly (over 3 minutes) bring the current up to a soak level. Deposition rate should be nearly zero but indicator should not remain exactly zero (if it does, reprogram inficon).
- Soak for 5 minutes, then slowly (over 3 minutes) bring current up to deposition level (enough to give 5-20 angstroms/second rate).
- Open >shutter and press yellow ZERO on inficon supply.
- Close shutter when accumulation reads desired thickness.
- Slowly (over 3 minutes) bring current down to zero. Particular care is needed to go slowly with silicon near its solidification point.
- Press red STOP on inficon supply, press white High Voltage OFF on ES-6 supply.
- After 3 minutes of fan cooling, turn off ES-6 power breaker, and unplug from wall.
- Slowly (over 1 minute) turn down heater variac supply, then turn off breaker.
RESISTIVE BOAT DEPOSITION
- Verify: Varian "filament supply" breaker off, knob at zero, meter switch to 500 Amps fs.
- Verify that inficon is programed.
- When chamber pressure below 1x10^-5 torr, turn on "filament supply" breaker.
- Slowly increase current until boat glows. Current will droop as boat heats up. Then slowly (over 3 minutes) continue to increase until source melts and deposition rate is as desired (e.g. 150A one Ti/Al2O3 boat used to deposit gold).
- Open shutter and press yellow ZERO on inficon supply.
- Close shutter when accumulation at desired thickness on inficon supply.
- Turn down current slowly (over 3 minutes).
UNLOADING CHAMBER
- Verify that ES-6 is off and unpluged from wall.
- Verify that resistive boat supply (varian "filament supply) is off.
- Verify that evapratrol supply is off and substrate temperature is under 100C.
- Turn off ion guage supply (NRC 836)
- Close main vacuum valve. Verify that roughing valve is closed
- Watch TC2 as you slowly crack open the vent valve. It should not change.
- Open the vent valve to vent the chamber. Close valve when vented.
- Check to see that bell jar is free by moving it to the side a bit (bear hug)
- Hoist the bell jar (some hand pressure will keep the vibration down)
- Remove substrate and sources.
SHUTDOWN
- Turn off diffusion pump breaker. It will take 40 minutes to cool down.
- Lower bell jar.
- Rough out the chamber. Throughout this process, TC2 must not exceed 1000mT; if it does, close the roughing valve, open the foreline valve to remove the builtup pressure, then continue roughing out the chamber.
- Close foreline valve. Slowly open roughing valve; listen for mechanical pump load.
- When chamber is below 200mT (TC1), close roughing valve and open foreline valve.
- When diffusion pump is cool:
- Close foreline valve.
- Unplug mechanical pump.
- Vent mechanical pump line (open blue handled valve near pump, close it when done).
- Turn off cooling water.
- Recap drain.
- Check or turn off: all breakers, DVM, ice point.
cgl 6/19/96, 5/97, 7/97