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Video Training Script for the E-Beam Evaporator
Part 1: Electron Beam Evaporator
The CVC Products Electron Beam 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 perpendicular to the surface of the substrate.
Types of Metals
The e-beam is usually used for titanium, chrome, gold, nickel, platinum, aluminum, and copper coatings. It can be used to evaporate most other metals as well.
Machine Specifications
The E-beam evaporator can hold up to six different evaporation sources. A cryo pump is used for rapid pump down. The E-beam can process samples in size from 4 inch wafers to less than 1 centimeter squared using the process plate. It can also process samples up to 20-3 inch or less samples using the process dome. The backside heater is disabled.
Typical Process
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. The metal evaporation source is then heated to a high temperature by a beam of electrons. This causes the metal to evaporate and be deposited on the substrate. Typical deposition rates range from two to five Angstroms per second.
Let’s now introduce our lab users.
Part 2: Overview of Parts of E-Beam Evaporator
We will now go over the various parts of the E-beam evaporator.
Part of the E-Beam Evaporator
We will begin with the ion gauge. It is used to display the chamber pressure when the chamber is under high vacuum. The pressure is measured in torr.
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 that a valve is open when the respective light is on.
The crucible selector moves the selected crucible into position for evaporation.
The Power Supply Controller controls the electron beam power supply.
The X Y sweep controller controls the position of the electron beam. For proper operation, the beam must move in a circle inside the crucible. The beam should not touch the edges of the crucible.
The shutter control opens and closes the shutter. Usually, the shutter is controlled by the deposition monitor. The shutter is closed while the metal is being heated. Once the metal is evaporated 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.
The hoist control raises and lowers the hood.
The deposition monitor shows the rate and deposition thickness of metal being deposited onto your samples. The monitor is also used to choose the recipe you want to run.
Part 3: Loading a Sample
We first want to go to the automatic valve controller and press the stop button and then the vent button. We will then wait a few minutes for the system to vent. Wait until the needle on the chamber pressure gauge reaches the right side of the display. We can tell the chamber is vented by either waiting for a clicking noise that will come from near the chamber, a hissing noise coming from the chamber, or by actually feeling the nitrogen gas coming out of the chamber by the seal.
Once you hear the clicking noise, push the stop button to close the vent. Then press the hoist up button on the hoist controller in order to raise the chamber all the way up.
WARNING: Do not try to hoist up the chamber before the chamber has completely vented. And be sure to use the hoist up button instead of using your strength.
Clean the area by vacuuming any flakes or debris that have been left on or around the sample. Cleaning the area helps create a better seal between the metal and the rubber.
WARNING: It is very important to vacuum the area. Do not forget to do it.
Next check the mirror that is located directly above the shutter. If the mirror is dirty, remove it and replace it with a clean mirror.
Check to see if the shutter is working properly. Go the Shutter controller and select manual mode on the manual/auto shutter button. Then test opening and closing the shutter by pressing the shutter open/close button. Set the manual/auto shutter button back to automatic before going on.
Now we go over to the crucible selector and select our evaporation source. In our case, we are using copper, so we press the copper button and wait for the light to turn on. This tells us that the crucible is in the proper position. However, you still need to check the crucible to see that it is aligned properly. You might need to first move the shutter out of the way in order to see the crucible. Then make sure the crucible is in a v-alignment.
First get a sample holding plate and put a screw in it. Then place a sample holding clip around the screw and tighten down the screw. Repeat this process for at least one more screw. Then place your sample on the sample plate and put the clips on top of your sample. This holds the sample in place.
Then place your sample plate on top of the sample holder. Be sure to place your sample facing down.
Now hoist the chamber down by pressing hoist down on the hoist controller. Once it has been hoisted down, press the start button on the valve controller. This will start pumping the pressure of the chamber down. After a few minutes, the chamber pressure needle will start moving and go down to about point five torr. The Hi-Vac light will then come on indicating that the valve is open for the cryo pump. Soon after the ion gauge controller will come on. This is indicated by the lights on the ion gauge controller changing from red to green and the counter displaying the decreasing pressure of the chamber.
We will wait for the pressure to come down to about the 5x10-7 to 2x10-6 range. However, if you are not concerned with the deposition quality, you can start at higher pressures. If you want a low pressure, it may take 30 to 45 minutes for the system to reach the pressure you want.
WARNING: Do not leave the area while waiting for the chamber pressure to decrease. You must monitor the E-Beam to ensure that the system is functioning properly.
Part 4: Programming a Recipe
The first thing we want to do is go to the program page by pressing F6. Then go to the process directory by pressing F2. From this page you can select the metal you want to use. In our case, we are using copper so we will use the arrows keys to select it. If you look at the top right hand corner, you see that the current metal is three. Now press F4 to select the active metal. The indicator will change to six to show that we are using copper.
Now we want to change the process by pressing F5. We want to change only two numbers on here: the final thickness and the thickness limit. We are going to change those numbers to 1 kilo angstrom per second. Type in 1000 and press the enter button labeled as E to change the final thickness. Repeat the process for the thickness limit. Once we’ve done that, press F6 to return to the process directory. Then go back to program by pressing F6 again. Then go to operate by pressing F6 for a third time.
Part 5: Turning on the Power Supply
Turn the keylock on the electron beam controller to ON and press the green ON button next to it. Before proceeding, you must wait for the power supply's cooling fans to reach operating speed. This will take about a minute. The power supply will make a clicking sound indicating that it is ready.
Next Press the "HI VOLTAGE" On button. Then set "FILAMENT" to ON
Part 6: Beam Alignment
Once the pressure has gone down to the desired level, press start on the deposition monitor. We can now adjust our beam.
Center the beam using the latitude and longitude knobs. You need to be simulataneiously looking inside of the chamber and rotating the knobs. Once you have done this, widen the beam using the amplitude knobs. Widen the beam as wide as possible without hitting the crucible.
WARNING: Make sure you are looking at the beam while adjusting the knobs. Doing so otherwise can cause damage.
Part 7: Closing Tasks
We need to shut down the power supply. We turn the off buttons in the counter-clockwise direction. We start by turning filament to off, high voltage to off, the button next to the keylock to off, and then we turn the keylock to off.
After doing so, we need to vent the chamber. This is done in the same way in which we did in the beginning of this video.
After the evaporation, the sample will be hot. Give some time for the metal to cool down before taking it out. Different metals cool down at different rates. Titanium takes the longest at 8 minutes and gold takes the shortest at just under a minute. Also remember that both the sample and the sample plate may be hot. As a general rule, wait at least 5 minutes for all metals to cool down or until the metal has stopped glowing. Please remember to be safe.
After removing your sample and lowering the cage, we need to pump down the system. We pump down the system by pressing the stop button and then the start button.
Part 8: Concluding Remarks
After watching this training video, you should have a good understanding of how to use the Electron Beam Evaporator. You should be familiar with the proper steps needed to:
- Load a Sample
- Program a Recipe
- Aligning Your Beam
- Shut down the system
If you have any further questions, please direct them to the trainer for this equipment. Please do not direct your questions to Charlie Turgeon.