Thin films are required for several processes—from manufacturing touch panels and glass to solar cells and displays. These layers are manufactured using a process called sputter deposition. The sputtering target is a vital piece in the procedure.
This article will cover all you need to know about sputtering targets.
Let’s dive right in.
What is a Sputtering Target?
A sputtering target is a raw material that helps produce thin films used in sputtering deposition/coating. It helps to coat different materials called the substrate. Substrates can be glass, displays, solar cells, etc.
Sputter targets can be circular, like the one shown below. Similarly, they can come in powdered form.
Sputter coating occurs in a sputtering system. The image below shows what this system looks like. The sputtering system is a vacuum chamber with a controlled pressure of 0.5 to two pascals.
The coating process begins with the introduction of argon gas until the system attains a low-pressure argon-filled environment.
Sputtering targets are usually negatively charged. Since argon has a positive charge, it is attracted to the target. When it collides with the sputtering target, it ejects atoms from the target surface. There is also a magnetic material/array in the system that reinforces the ejection of these atoms.
Then, the ejected atoms travel opposite the target to coat the substrate layer-by-layer until they form a uniform thin film.
One of the most popular target materials used as sputtering targets, especially for semiconductors, is aluminum. This is thanks to its versatility and superior heat resistance. However, you still need a certified aluminum powder supplier to get the best possible coating quality.
4 Uses of the Sputtering Target
The sputtering target is a vital piece for coating most of the materials you use today. In this section, we will discuss the four popular uses of the sputtering target.
The sputtering target is necessary to create several thin layers in semiconductors. These include microchips, flat panel displays, etc. The target is an integral part of the wiring and barrier layer of the semiconductor.
Besides, in wafer manufacturing, these targets are necessary to produce conductive layers and metal grids. The importance of the sputtering target further extends to chip packaging, where it is used to manufacture the wiring layer and metallic layer just below the bump.
The targets used for semiconductors are the most demanding when it comes to purity and technology. They will not meet the required electric performance if the impurity level is higher than required. This can lead to circuit damage. Metals such as Aluminum, Tantalum, Titanium, Copper, etc., are recommended for the process. A mil-spec supplier can help ensure this purity.
2. Solar Cells
The sputtering target is an integral part of thin film solar cells, which is the second and one of the most efficient generations of solar cells. With the target coating, this generation promises 10 to 20 years of lifetime with the best payback time.
There are many targets used for solar cell coating. The first is cadmium telluride (CdTe) sputtering target. This target works with the least carbon footprint and water usage during the sputter deposition process. With CdTe, you also don’t have to worry about energy deficit in the short term. However, cadmium is a component of the target, which can be toxic.
Another target used is the CIGS target. CIGS is the combination of copper, indium, gallium, and selenium. Films prepared using CIGS show superior light absorption and power-generating potential.
You can also use the gallium arsenide target, which maintains its efficiency even at overly high temperatures. It is most suitable for solar cells used in areas with high radiation and ultraviolet rays, such as aerospace.
3. Low Radiation-Coated Glass
Energy-saving glass or low radiation-coated glass is replacing the traditional glass today. This is partly because of its aesthetics and its energy-saving and light control capabilities. The magnetron sputtering technique is used to manufacture this low radiation coated glass.
Silver sputtering targets are very popularly used for energy-saving glasses. This is due to their elevated conductivity, ductility, and malleability. Another material is chromium sputtering target. This target can make a film as tiny as 2 to 10 micrometers. Chromium is hard, doesn’t wear off easily, and can resist impact. These are the features you want in your glass.
Titanium sputtering target is perhaps the most versatile choice. Whether you’re using it for semiconductors or low radiation-coated glass, it slots in seamlessly.
Other important target materials to note are the zinc tin target, silicon aluminum target, and titanium dioxide target.
4. Optical Glass
Sputtering targets are also necessary components for making coatings of sunglasses, optic filters, eyeglasses, and other optics glasses. You can superimpose these thin films on these optical components. These thin films further optimize how light is transmitted or reflected in the optical glass. In essence, sputtering targets are responsible for the anti-static safety property of lenses and other visors.
Coating with the target material can help you elevate the luster and lifetime of the optical glass. It also minimizes abrasion and increases the glass’s thermal conductivity.
The targets used in this case are similar to the ones used in the energy-saving glass coating. Their difference lies in their manufacturing procedure.
There are two popular sputtering processes for optical glass coating. The first is ion beam sputtering. This involves bombarding the target with high-energy ion beams. This will help eject the target atoms and form a hard, dense, and smooth film on the optical surface.
The other sputtering process is advanced plasma sputtering. This process uses a hot cathode to eject the atoms instead of high-energy beams. This process gives you smooth and hard coating on the optical surface, reinforcing its stability. It is a very versatile process. Thus, it is the preferable choice for high-volume and more demanding coating processes.
From automobiles to electronics and other applications that require thin films, the sputter target is integral. It helps you add more functionality and durability to the substrate. There are various types of target materials, each suitable for various purposes. Some of them include zinc, titanium, CIGS, CdTe, and others.
These targets have various applications. You can use them to make components of semiconductors and solar cell coatings. They also come in handy when you want to coat energy-saving and optical glasses.