[MUSIC] Hello, I'm Nan Jokerst, and this is our in-depth video about electron beam vacuum deposition of thin films. We use vacuum systems to deposit thin layers of materials, such as metals and insulators, onto our substrates. The thicknesses of these vacuum deposited layers are very thin, on the order of 5 nanometers to 250 nanometers. The three most common thin film deposition techniques are thermal evaporation, electron beam evaporation, and sputtering. In this video, I will introduce you to the process of electron beam evaporation also called e-beam evaporation. This technique is similar to thermal evaporation but the material is heated up a little bit differently. In thermal evaporation, electrical current is used to heat a boat so that the source material in the boat melts and evaporates. In electron beam evaporation, a stream of electrons or an electron beam is aimed at a high purity source material that we want to evaporate. This beam of electrons heats the material to its melting point and then evaporates the source material. This electron beam is well confined. And one of the advantages of e-beam evaporation is that we can rotate different source materials into the path of that electron beam. So that we can deposit multiple material sequentially without opening the vacuum system which is also called a breaking vacuum or venting. An e-beam evaporator has two main components. First is the electron source or electron gun which produces the beam of electrons. Second, the crucible is where the source material that we want to evaporate is contained. This is like the boat for thermal evaporation. Here is a crucible with gold in it for the source material. Contained within that electron gun is a filament, the source of the electrons. And magnets for focusing that electron beam and directing it towards the crucible. The electron beam is generated by heating the metal filament to the point that it glows bright, about 2,500 degrees centigrade. At this temperature, electrons are so energetic that some of them leave the surface of the filament. These electrons are then accelerated toward the source material using a high voltage electrode. And a set of magnets steer and focus the beam onto the source material to be evaporated. The power level can be to control by adjusting the filament current. This is very important, since some materials require lower power to melt and can burn at higher power, while others require higher power just to melt. The source material is contained in a small crucible. Depending upon the material being evaporated, the crucible may be made of tungsten, copper, or even a ceramic for very high temperature deposition. Because that electron beam is well confined in space, only a small area of the source material is heated. This means that there's room for multiple small source materials in the vacuum chamber. Systems that hold four materials are very common and they are called four pocket hearths. There are four crucibles that fit into the hearth, and each crucible can hold a different source material. So that you can have up to four layers of different materials deposited without breaking vacuum. The hearth is a rotated holder of copper which is water-cooled. The water cooling prevents the crucible material from melting and mixing with the source material or with the hearth itself. In this configuration, several different materials can be deposited or sequential back and forth can also be deposited of multi-layer materials. Electron beam evaporation is one thin film deposition option. Be sure to take a look at the thermal evaporation and sputter deposition videos to learn about two other commonly used thin film vacuum deposition techniques. I hope you enjoyed this lesson. Thank you for joining me today.