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Thin Films
Published in Yip-Wah Chung, Monica Kapoor, Introduction to Materials Science and Engineering, 2022
Generally, we can classify thin-film deposition techniques into two broad categories: physical vapor deposition (PVD) and chemical vapor deposition (CVD). In PVD, materials comprising the thin film are delivered to the substrate by physical means, such as evaporation, sputtering, or laser ablation. In CVD, the thin film is formed on the substrate by a chemical reaction. The demarcation line between PVD and CVD is not always distinct. For example, in the reactive sputtering of TiN, Ti is sputtered from a target in a background pressure of nitrogen. On the substrate, the arriving Ti atoms react with adsorbed nitrogen to form TiN. In this case, Ti atoms are delivered to the substrate by physical means (sputtering), but the final product TiN is formed by a chemical reaction between Ti and atomic nitrogen. In molecular beam epitaxy (MBE) synthesis of gallium arsenide, gallium and arsenic vapors produced by sublimation (a physical process) react to form the compound on the substrate. In this section, we present an overview of three deposition techniques: evaporation, sputtering, and CVD.
Epitaxy
Published in Kumar Shubham, Ankaj Gupta, Integrated Circuit Fabrication, 2021
PVD is a combined set of processes used to deposit thin layers of material, typically in the range of few nanometers to several micrometers. PVD is basically unlimited choice of coating materials: metals, alloys, semiconductors, metal oxides, carbides, nitrides, cermets, sulfides, selenides, tellurides etc. PVD process containing of three fundamental steps: Vaporization of the material from a solid source supported by high temperature vacuum or gaseous plasma.Transportation of the vapor in vacuum or partial vacuum towards the substrate surfaceCondensation onto the substrate to generate thin films
Growth Techniques
Published in Alan Owens, Semiconductor Radiation Detectors, 2019
A large class of epitaxial techniques relies on delivering the components that form a crystal from a gaseous environment. If the atoms or molecules emerging from the vapor can be deposited on the substrate in an ordered manner, epitaxial crystal growth can occur. There are two main delivery systems – CVD and PVD. The essential difference between the two is that CVD is based on chemical processes in gaseous phase and the substrate surface, whereas PVD is based on evaporation and condensation or the collisional impact of solid material on the substrate. Both are non-equilibrium19 growth techniques requiring a high degree of temperature control and are described in the following sections. For a review of CVD see Jones and Hitchman [52] and for PVD, see Mattox [53].
A comprehensive review of vapour deposited coatings for cutting tools: properties and recent advances
Published in Transactions of the IMF, 2022
N. Ariharan, C. G. Sriram, N. Radhika, S. Aswin, S. Haridas
PVD is a popular technique used to deposit thin films over a substrate material by either atomising or vaporising the target material. Although introduced in the early twentieth century, this method is still being studied today by scientists rigorously seeking to optimise its process parameters so as to make the deposition more efficient and effective. Although the majority of the deposition process remains identical, the process can be altered or enhanced by even subtle variations in process parameters such as changes in ionisation rate, substrate material, target material, type of environment maintained during deposition (vacuum, gaseous, etc.), substrate geometry, pressure, temperature, type of power supply (DC, AC, pulsed), deposition angles, etc.35 PVD can be broadly classified into two categories: evaporation-based and sputtering-based.35–38 Although the deposition process can be altered into many forms based on the requirements, prior to deposition, the general procedure first involves the development of the required atmosphere in the chamber (vacuum, gaseous, etc.) and pre-treatments on the substrate surface (mechanical pre-treatment, chemical cleaning, ion etching).35, 39
Coated and uncoated reinforcements metal matrix composites characteristics and applications – A critical review
Published in Cogent Engineering, 2020
Karthik B M, Gowrishankar M C, Sathyashankara Sharma, Pavan Hiremath, Manjunath Shettar, Nagaraj Shetty
Reinforcement surfaces can be coated with non-metallic or metallic compounds, to improve adhesion (wettability), mechanical properties and to evade any unpleasant chemical reaction within the matrix and reinforcement at elevated temperatures. There are different methods of coatings like Electroless Nickel Plating (EN), Chemical Vapour Deposition (CVD), Physical Vapour Deposition (PVD), etc. PVD is a technique where the condensed phase material enters to a material phase of vapour as thin film. Sputtering and evaporation are the most common PVD processes (Navinšek et al., 1999; Sathyashankarasharma et al., 2019; Shankar et al., 2018; S. Sharma et al., 2018). PVD is used for high melting point and low vapour pressure materials. CVD is a deposition method to chemically produce pure, high-performance solid materials. In the general CVD process, the desired output is produced when the substrate reacts and decomposes when exposed to several volatile precursors (Chou & Liu, 2005; Sathyashankarasharma et al., 2019). In Electroless Nickel plating (EN) technique, plating of nickel phosphorous alloy by the process of chemical reduction on the catalytic metal surface. The deposits from EN processes have high corrosion resistance, lower wear surface. They have a noticeable lower amount of porosity, which results in outstanding wearing off and the abrasion resistance of the thickness quotient (S. S. Sharma et al., 2016; Sánchez et al., 2010).
Influence of cutting tool material on machinability of Inconel 718 superalloy
Published in Machining Science and Technology, 2021
Thrinadh Jadam, Saurav Datta, Manoj Masanta
Cermet and PCBN tools are coated through PVD route. During such deposition method, material undergoes phase change i.e. from condensed phase to vapor phase, and then, returns back to a thin film condensed phase. PVD coatings are harder, possesses higher corrosion resistance than electroplated coatings. In addition, they have adequate hot strength, good impact strength, outstanding abrasion resistance which protect tool substrate against aggressive cutting environment. PVD technique is environmentally-friendly when compared to other coating methods. Details of tool microstructure along with results of elemental analysis on tool coating materials are provided below.