Varian 3118 Thermal Evaporation System

Manuel AldreteUniversity of California Berkeley

Faculty Mentors: Professor Henry LeeGraduate Student Mentor: Denise Ullery

IM-SUREAugust 26, 2005

Evaporator Background The Varian is a high vacuum thermal

evaporation system It is currently set up for evaporation of

up to three different materials A quartz crystal rate monitor allows

direct readout in Å/s of rate and in kÅ for thickness

The system uses a cryopump to create a very clean vacuum and should achieve a base pressure of about 7x10-7 torr

Front Control Panel

Evaporation Materials Run a high current through

the boat to resistively heat the evaporation source. The boat material is dependent on our evaporation material

The vapor pressure increases with temperature and creates a point source of evaporated material

1. Evaporator Operation Check the base pressure

of the system using the ion gauge (<3x10-6 torr)

Degas for most accurate pressure reading. Turn off filament and hit degas button. Leave in degas mode for 5-10 min. This removes adsorbed ions.

The ion gauge should not be used for pressures higher than 10-4 torr

2. Venting the System Close the HI VAC valve by setting the HI VAC switch to closed The ROUGH and FORE switches should be set to closed Vent the system using the switch labeled AIR RELEASE. This

takes about 2 min and is finished when the bell jar is loose Switch AIR RELEASE to closed once the system is vented

3. Checking Source

Verify that power supply lights are not on

Toggle hoist switch to left until the bell jar reaches a sufficient height

With gloved hands remove planetary fixture from track and place inverted on bench covered with lint free cloth

Check boats and make sure there is enough material to do evaporation and make sure there is good contact to the electrodes

4. Loading Wafers Remove wafer from

individual wafer tray using tweezers

Press down on coil spring on backside of planetary fixture to release wafer holder clip

Carefully insert wafer under wafer holder clip with tweezers. Repeat for all wafers to be loaded.

Place planetary fixture back on track and verify that it rolls freely

5. Evaporator Pumpdown Wipe the gasket clean and lower the bell jar using the hoist

switch While holding down the bell jar flip open the ROUGH switch Allow the system to be roughed down to <200 millitorr before

opening the gate valve and exposing it to the cryopump Once the pressure reaches about 200 millitorr flip open the HI

VAC switch and the system should be pumped for about an hour and achieve a pressure <3x10-6 torr before proceeding with an evaporation

6. Source Evaporation Turn the fixture drive control switch to on and adjust the knob

to desired speed Turn on Inficon IC6000 and press 1 to verify settings are*

FILM #1 PGM Locked 1. Density 19.30 G/CC 2. Z-Ratio 0.381 3. Tooling 150% 4. Sensor 1 5. Source 1 6. Gain 35 7. Approach 10 8. Limiter 10.0% 9. Soak P1 13% 10. Ramp T1 00:12 M:S 11. Soak T1 00:12 M:S 12. Soak P2 22% 13. Ramp T2 00:12 M:S 14. Soak T2 00:12 M:S [depress down arrow] 15. Rate 5.0 A/S 16. Shutter DLY 00:00 M:S 17. Final THK 1.500 KA 18.Thk LMT 0.0000 KA 22. Idle Pwr 0% 24. Max Pwer 90%

Verify that the switches on the SCR are set to REMOTE

*Example located in Varian 3118 Manual

7. Evaporate Source Turn the power supply on

and verify that red light is on

Push the START button on the IC6000

Observe rate (5 Å/s) and thickness (increases to 1.5

kÅ) Evaporation is now

complete Turn power supply off

8. Vent System and Remove Wafers

Vent by closing the HI VAC switch and after about 5 s opening the AIR RELEASE switch

Once atmospheric pressure is reached raise the bell jar

Once again with gloved hands remove the planetary fixture and place on clean surface

Remove wafers using tweezers

www.Chipscapes.com/chipscapes/CS03.htm

Thank You!