CVC Products Filament Evaporator

Trainers

The filament evaporator is used to coat samples with various metals. Unlike sputtered films, evaporators only coat the surface facing away from the substrate. Evaporators will provide very little coating to the sides of any features that are perpendicualar to the surface of the substrate. The filament evaporator is ordinarially used for titanium, gold, nickel, platinum, aluminum, and copper coatings. It can be used to evaporate most other metals as well. In a typical process the chamber is pumped down to a pressure of 5 x 10^-7 torr to prevent air molecules from interrupting metal atoms as they travel from the evaporation source to the substrate. Then the metal evaporation source is heated to a high temperature by a tungston filament. This causes the metal to evaporate and be deposited on the substrate. Typical deposition rates range from two to five Å / second.

In most cases metal depositions are performed in the CVC electron beam evaporator or in the CVC DC sputterer. The filament evaporator is a good choice for samples that need to be evaporator coated (to avoid coating the sides of rough topologies) and are sensitive to x-ray radiation that may be emitted the the electron beam gun in the e-beam evaporator.

Features

cryo-pump for reduced pump-down time
low voltage high current resistance heating

	Ion Gauge The ion gauge is used to display the chamber pressure when the chamber is under high vacuum. The pressure is measured in torr.
	Valve Controller The valve controller controls the valves that are used to control the chamber pressure. The gauge in the middle of the controller shows the chamber pressure in torr. The lights on the left side of the gauge show the status of the system's valves. A valve is open if the light is on.
	Shutter Control The shutter control opens and closes the shutter. Ordinarily, the shutter is controlled by the disposition monitor. The shutter is closed while the metal that is being evaporated is being heated. Once the metal is evaporating at the correct rate, the shutter is opened, exposing the sample to the evaporation. Once the desired amount of metal has been deposited, the shutter is closed to prevent further deposition.

Operating Instructions

I. Before Starting

Prepare sample for processing.
Mount sample securely to sample pallet. Remember that the pallet will be mounted upside down in the evaporator.

II. Vent System

Push "STOP" on valve controller.
After you hear the high-vac valve close, press vent.
The system has a sensor which will not allow the hoist to be raised until the chamber has reached atmospheric pressure. Once you hear nitrogen coming out of the seal, raise the hoist by holding the "HOIST UP" button on the hoist controller.
Use the cleanroom vacuum with the SOFT TIP to vacuum around the seal of the hood. If you do not know which is the soft tip, contact a MiRC staff member. Using the vacuum with the hard metal only can scratch the seal area.

II. Load System

Open the shutter with the shutter controller.
If the metal shielding is in the chamber, remove it. Be careful not to hit the deposition detector while removing the shielding.
For each metal to be evaporated, mount a tungsten boat between the center electrode and one of the outer electrodes at the base of the chamber.
Place one or two pellets in each boat. Note which electrode pair corresponds to each metal.
Replace metal shielding over electrodes. Make sure that the cut out section in the shielding top is under the deposition detector. If it is not, the detector will not function properly.
Open and close shutter several times to insure that the shielding will not interfere with shutter operation.
Place sample pallet into the pallet holder at the top of the chamber, sample side down.

III. Pump System Down

Press "HOIST DOWN" on the hoist controller to lower the hoist.
Once the hoist is lowered completely, press "START" on the valve controller.

IV. Set up deposition monitor.

Turn the deposition monitor on with the "POWER" button.
Select 8 ("DATA MODE") from the menu that appears when the monitor is turned on.
Using the chart posted on the control panel for reference, select the metal that you are depositing by pressing "FLM #" followed by the number for the metal. The selected layer is displayed near the lower right corner of the display.

V. Perform evaporation

Set the electrode selector the electrode pair for the metal you are evaporating.
When the chamber has reached the desired pressure, turn the filament power switch to on.
Using the knob on the filament current controller, slowly increase the filament current (1 amp every 90 seconds) until the desired deposition rate is reached.
When you are ready to begin deposition, open the shutter using the shutter controller and press "ZERO THK" on the deposition monitor at the same time to zero the monitor.
You will need to monitor the deposition rate and adjust the filament current controller accordingly throughout the deposition.
When you are finished depositing, close the shutter.
Slowly reduce the filament current to zero.
If you are evaporating other metals, set the deposition monitor the next metal and evaporate that metal (see step IV - 3). If you are finished evaporating, turn the filament power switch off. Wait ten minutes before venting the system to allow the filament to cool.

VI. Vent System

Wait ten minutes after shutting the filament off to vent the system.
Press "STOP" on the valve controller.
Wait until you hear the high-vac valve close, then press "VENT"
The chamber has a sensor which will not allow the hoist to raise until the chamber has reached atmospheric pressure. Wait until you hear nitrogen coming out of the seal then raise the hoist by pressing "HOIST UP" on the hoist controller.

VII. Remove pallet and boats.

Remove the sample pallet from the chamber.
Remove the shielding from the base of the chamber and remove the boats. Be careful – the shielding and boats may be hot.
Clean the chamber with the soft tip on the vacuum.

VIII. Pump down

Lower the hoist by pressing "HOIST DOWN" on the hoist controller.
Press start on the valve controller.
Enter this run in the log book.

Problems? Contact the MiRC Technical Staff.