E-Beam Evaporation: Sample Deposition Demonstration

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Del curso dictado por Duke University

Nanotechnology: A Maker’s Course

498 calificaciones

Duke University

Nanotechnology: A Maker’s Course

498 calificaciones

How can we create nano-structures that are 10,000 times smaller than the diameter of a human hair? How can we “see” at the nano-scale? Through instruction and lab demonstrations, in this course you will obtain a rich understanding of the capabilities of nanotechnology tools, and how to use this equipment for nano-scale fabrication and characterization. The nanoscale is the next frontier of the Maker culture, where designs become reality. To become a Nanotechnology Maker pioneer, we will introduce you to the practical knowledge, skills, and tools that can turn your nanotechnology ideas into physical form and that enable you to image objects at the nano-scale. This course has been developed by faculty and staff experts in nano-fabrication, electron beam microscopy, and nano-characterization through the Research Triangle Nanotechnology Network (RTNN). The RTNN offers training and use of the tools demonstrated in this course to schools and industry through the United States National Nanotechnology Coordinated Infrastructure program. The tools demonstrated in this course are available to the public through the RTNN.

De la lección

Nanofabrication: Vacuum Pumps and Thin Film Vacuum Deposition

In this module, we will discover how and why a vacuum environment is required in nanofabrication, compare the operation of three types of vacuum pumps, and look at vacuum deposition of thin films using three different methods: sputter evaporation, e-beam evaporation and thermal evaporation.

Thermal Evaporation: Basic Function6:39

Thermal Evaporation: Sample Deposition Demonstration6:46

E-Beam Evaporation: Basic Function4:59

E-Beam Evaporation: Sample Deposition Demonstration5:13

Sputter: Basic Function4:02

Sputter: Sample Deposition Demonstration9:14

Conoce a los instructores

Nan M. Jokerst
J. A. Jones Professor of Electrical and Computer Engineering
Electrical and Computer Engineering, Duke University
Carrie Donley
Director of CHANL (Chapel Hill Analytical and Nanofabrication Laboratory)
Applied Physical Sciences, UNC Chapel Hill
James Cahoon
Assistant Professor
Chemistry, UNC Chapel Hill
Jacob Jones
Professor
Materials Science and Engineering, North Carolina State University

[MUSIC]

To keep the chamber clean, it is left under vacuum.

So first, we vent the chamber and

then we can open the door to the vacuum chamber and look inside.

This vacuum chamber uses a mechanical pump and a cryopump.

Here is the port that leads to the cryopump located under the vacuum chamber.

Of course,

this valve is currently closed as we cannot expose the cryopump to room air.

The material we wish to evaporate is held in what is called the hearth.

In this case, we want to evaporate gold.

The gold is contained in a small metal crucible.

This crucible is then placed in the hearth.

This particular instrument can accommodate

up to four different materials in the hearth.

The electron gun is located here.

Remember, the electron gun is a source of the electron beam that heats the sample.

And the sample is placed at the top of the chamber in this dome-shaped holder.

Like many thin film deposition instruments,

this evaporator uses a thickness monitor, which is here.

So, we can monitor the film thickness that is being deposited.

Let's hold our sample into the dome shape holder.

In this example, we will use a 50 mm diameter silicone wafer as our sample.

We place the wafer in the holder and secure it with the clips.

We reinstall the dome into the chamber.

We also must verify that our desired material is in the crucible.

Today we will evaporate gold, so we index to the gold crucible.

As we can see, there is gold in the crucible.

It is solid now since it is room temperature, but during deposition,

it will be heated so that it melts and evaporates.

Let's close the chamber and begin the automated pump down sequence.

Remember this vacuum chamber utilizes a cryopump.

So, the pump down sequence using the mechanical pump to rough out the system

to a few torr, then the cryopump is used to achieve high vacuum.

Here's the cryopump controller, indicating the temperature of the cryopump.

We can see that it's currently at 11 degrees Kelvin,

that's -262 degrees Celsius.

It is within the normal operating range.

We will let the system pump for the next hour or so and come back then.

The system has been pumping for an hour and 30 minutes.

The pressure in the chamber is less than 5 times 10 to the -6 torque

which is the maximum pressure the system allows for evaporation.

So we are ready to evaporate our metal.

We can read the pressure on this digital gauge.

We can now begin the E-beam deposition process.

First we select a recipe.

This tells the computer which material or

sequencing materials that we want to deposit.

We then enter the desired thickness.

Here we enter 75 nanometers, and

then press the start button to begin the process.

The process is automated, so the computer controls the electron beam power and

time and monitors the thickness using the thickness monitor.

After a minute or

so, the electron beam has heated the crucible enough that it begins to glow.

We can look through the glass view port into the chamber and

see the glowing crucible.

At this point, the gold has melted.

It will be heated a little more so that it readily evaporates.

The thickness monitor will tell the computer when we've reached

our desired thickness and the process will halt.

We can see the thickness monitor indicating the thickness in real time.

Okay, we've reached our desired thickness and the process has automatically stopped.

After a cooldown period of a few minutes,

the system will allow us to vent the chamber.

Remember, venting the chamber means we bleed nitrogen gas into the chamber

until the pressure in the chamber equalizes with the pressure in the room,

at which point we can open the chamber door.

Let's vent the chamber now.

After a couple of minutes, the chamber pressure equals the room pressure.

Now we can open the door.

Let's remove our wafer from the dome.

You can see the nice gold color film.

Here's the wafer before and after gold deposition.

Now we replace the dome, close the door, and

pump down the system, so it's ready for the next user.

I hope that you've enjoyed the demo of E-Beam evaporation.

Thank you for joining us today.

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