1) The magnetron sputtering theory.
Permanent magnets embedded in the target material surface create a magnetic field of 250–350 gauss, which is combined with the high voltage electric field to create an orthogonal electromagnetic field in the sputtered target pole (cathode) and the anode. This is done in a high vacuum chamber filled with the necessary inert gas (typically Ar gas).The target is added with a certain amount of negative high voltage, the electrons from the target are subject to the action of the magnetic field and the ionization of the working gas increases. A high density plasma is then formed near the cathode, where the Ar ions are accelerated under the influence of the Lorentz force and fly towards the target surface, bombarding the target surface with a very high energy particle.so that the atoms sputtering out of the target adhere to the momentum conversion principle with a high degree of precision Using the kinetic energy conversion principle, the sputtered atoms on the target fly off the surface and toward the substrate to deposit a layer. Magnetron sputtering is often separated into two types: DC sputtering and RF sputtering. DC sputtering equipment operates on a straightforward basis and sputters metals at a rapid rate. As opposed to reactive sputtering, which is used to create compound materials including oxides, nitrides, and carbides, RF sputtering has a wider range of uses and can sputter non-conductive materials in addition to electrically conducting ones.When RF frequency is raised, the process transforms into microwave plasma sputtering. Nowadays, microwave plasma sputtering of the electron cyclotron resonance (ECR) type is most frequently utilized.
2) Magnetron sputtering target types.
Targets for metal, alloy, and ceramic sputtering include metal, alloy, and ceramic sputtering coating targets, as well as boride ceramic sputtering targets, carbide ceramic sputtering targets, fluoride ceramic sputtering targets, nitride ceramic sputtering targets, oxide ceramic targets, selenide ceramic sputtering targets, silicide ceramic sputtering targets, sulfide ceramic sputter (InAs).
Editor Voice, [2] Application Areas
We all know that the downstream application industry's thin film technology development trend and the development trend of target materials' technology are closely related, so as the application industry advances the technology of thin film components or products, the target material technology should also advance. producers of Ic, as an illustration. Recently focused on the development of low resistivity copper wiring, it is anticipated that in a few years the original aluminum film will be largely replaced, necessitating the urgent development of copper targets and the necessary barrier layer target material. In addition, the original cathode ray tube (CRT)-based computer monitor and television market has been largely supplanted by flat panel displays (FPD) in recent years.will also greatly raise the market and technological demand for ITO targets. Moreover, in storage technology. Demand for high-density, high-capacity hard drives and high-density rewritable optical discs is on the rise. The demand for target materials in the application business has changed as a result of all of these. The primary applications for target materials will be discussed in the sections that follow, along with the development trends for these applications.
3）Microelectronics
Of all the application industries, the semiconductor industry has the strictest quality standards for target sputtering films. Currently, silicon wafers up to 12 inches long (300 epitodes) are produced, although connection widths are getting narrower. The targets produced must have a better microstructure due to the silicon wafer manufacturers' demands for big sizes, high purity, reduced segregation, and fine grains. A significant factor influencing the rate at which the film is deposited has been found to be the target's homogeneity and crystalline particle diameter. Also, the target's purity has a significant impact on the purity of the film.A target purity of 99.995% (4N5) copper could have been sufficient in the past to satisfy semiconductor manufacturers' needs for the 0.35pm process, but the 0.25um process of today and even the 0.18um art process for unmetered devices require a target purity of 5 or even 6N or more. Copper has a lower resistivity to meet and a stronger resistance to electromigration than aluminum does! The conductor approach necessitates sub-micron wire that is smaller than 0.25um, but it also has additional drawbacks, like copper's weak bond to organic dielectrics. And quick to respond, causing the chip's copper connector line to corrode and break.It is necessary to create a barrier layer between the copper and dielectric layer in order to address these issues. The majority of blocking layer materials have high melting points and high resistivities for the metal and its compounds, resulting in a layer thickness of less than 50 nm and effective adhesion between copper and dielectric materials. The blocking layer material's connectivity between copper and aluminum is distinct. It is necessary to create fresh target materials. connectivity of copper between the blocking layer and the target materials Ta, W, TaSi, WSi, etc. Yet refractory metals Ta and W exist. Given the difficulty of production, researchers are currently looking into other materials, including molybdenum, chromium, and Taiwan gold.
4）To illustrate
The market for computer monitors and televisions has been significantly impacted by flat panel displays (FPD), mostly in the form of cathode ray tubes (CRT), which will also push the technical and market need for ITO targets. iTO targets come in two different varieties nowadays. One involves using an indium-tin alloy target, while the other involves mixing and sintered nano-state indium oxide and tin oxide powder. By using DC reactive sputtering, indium-tin alloy targets can be used for ITO thin films, however the target surface will oxidize and affect the sputtering rate, and it is difficult to find large-size Taiwan gold targets.
These days, the L-IRF reactive sputtering coating process is typically used to create ITO targets. The deposition speed is quick. And can precisely manage the film's thickness, high conductivity, good uniformity, and strong adherence to the substrate, among other properties. However, the target material production faces challenges since it is difficult to sinter together indium oxide and tin oxide. Often utilized as sintering additives, ZrO2, Bi2O3, and CeO may produce targets with densities between 93% and 98% of the theoretical value. The additives have a significant impact on how well ITO films made in this manner operate.Bi2O3, which melts at 820 °C and has already begun to vapourize beyond the sintering temperature of 500 °C, is used as an additive by Japanese scientists. This makes it possible to produce an ITO target that is comparatively pure when using liquid phase sintering. Moreover, the prerequisite procedure is made simpler by the fact that the necessary oxide raw material need not necessarily be nanoparticles. In the "current priority development of information industry important areas guide" published in 2000 by the National Development Planning Commission and the Ministry of Science and Technology, ITO major target material is also mentioned.
5）for holding
CoFCu multilayer composite film is a popular giant magnetoresistive film structure nowadays. In the field of storage technology, the development of high-density, high-capacity hard disk demands a significant number of giant magnetoresistive film materials. Magnetic discs manufactured from the TbFeCo alloy target material, which is still being developed, have a high storage capacity, a long lifespan, and the ability to be repeatedly wiped without touch. TbFeCo/Ta and TbFeCo/Al form the layers of the composite film structure used in today's magnetic discs.The TbFeCo/AI structure's Kerr rotation angle can reach 58 while that of TbFeCofFa can be as low as 0.8. It has been discovered that the target material's low magnetic permeability and high AC partial discharge voltage act as electrical resistors.
Phase change memories (PCMs) based on germanium antimony telluride have demonstrated significant commercial potential as a replacement memory technology for NOR type flash and as a component of the DRAM market. However, one of the obstacles to faster scaling is the lack of fully hermetic cells that can be produced to further lower the reset current. For today's data-centric, highly portable consumer, lower reset currents can boost data bandwidth, prolong battery life, and reduce memory power consumption.
