Introduction
Surface treatments using ion implantation dates back to about five decades and has been extensively used for various applications in the semiconductor industry. It is a material modification process that changes the physical and chemical properties of the surface of an item without altering its basic structure. Ion implantation involves the energetic bombardment of a substrate surface by with ions accelerated to high energy levels, in the presence of an electric or magnetic field. The ions penetrate into the substrate and get embedded into the near-surface region forming a new near surface layer. This near-surface layer has properties different from that of the bulk material due to the substitution of certain atoms of the original substrate material with the implanted ions.
Theory of Surface Treatment
The basic behavior of ion implantation is given by the sputter effect, which states that under bombardment of the high-energy ions, atoms sputter and the surface is eroded through a process that is called sputtering. The ions, which are generally energetic, get implanted into the near-surface region and deposit some energy into the near-surface region as they get slowed down. This results in the near-surface region getting heated up and eventually, a thin layer is formed at the interface between the substrate and the near-surface region, which is called the implantation zone. Thus, the implanted ions get trapped at the interface and bond with the atoms of the substrate material. Depending on the type of ions implanted and their energy levels, this layer can be called the amorphous layer, cluster layer or interface layer.
Advantages and Disadvantages
Ion implantation is an efficient and cost-effective technique for making modifications to a material’s surface. It works on a very small physical scale, less than a micron in width that is not otherwise accessible by other conventional processes. Additionally, the process is highly precise, minimally invasive and almost instantaneous.
Having said that, there are some difficulties in the process, the main being that ion implantation works only on certain surfaces, namely single crystal silicon surfaces. Additionally, due to the size and scale of the process, many irregularities and imperfections are unavoidable and need to be accounted for. Additionally, during the process, there is a risk of causing thermal and mechanical damage to the materials being implanted.
Applications
Ion implantation technique has found numerous number of applications and is used to modify the surface of a variety of materials, such as polymers, metals, glasses and ceramics. This technique can be used for creating thin films, hard coatings, corrosion-resistant layers, wear-resistant layers, heat-resistant layers and other layers with desired properties. Additionally, ion implantation can also be used for doping semiconductor materials, enabling them to achieve desired electrical properties for specific applications.
One of the most important applications of ion implantation is in the semiconductor industry, where it serves as an effective method for doping some materials such as silicon and germanium to produce high performance transistors. Additionally, ion implantation is used in medical devices and implants to increase their longevity and improve their biocompatibility. Other applications include electronic packaging and device fabrication.
Conclusion
Ion implantation is a relatively new technique that has rapidly gained popularity due to its cost effectiveness and wide range of applications. It is an efficient and precise process that can be used to modify the surface of materials and make them suitable for specific applications. The process has numerous advantages such as being fast, non-invasive and cost-effective and also has certain limitations such as its limited applicability in certain materials and its propensity to cause certain irregularities and imperfections in impurities. Overall, ion implantation is a useful and viable tool for providing materials with desired surface properties.
