Varian 3118 Thermal Evaporation System

1. Varian 3118 Thermal Evaporation System Manuel Aldrete University of California Berkeley Faculty Mentors: Professor Henry Lee Graduate Student Mentor: Denise Ullery IM-SURE August 26, 2005

2. 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

3. Front Control Panel

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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 #1PGM 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

11. 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

12. 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

13. Thank You!