Principle of sputtering thin film deposition technology
Time：2021-11-11 Author：Changsha Xinkang scientific research material service platform
Sputter deposition is a physical vapor deposition technique that bombards a target with high-energy particles, which are ejected from a solid target. It is an electronic process for depositing thin films of metals or other materials onto various surfaces. In most cases, sputtering is used to make thin layers on silicon wafers, solar panels and displays.
How sputter deposition works
Sputter deposition is carried out in a vacuum chamber in which an inert gas is introduced, most commonly argon ions. Two items are placed in this chamber: the item to be electroplated, also called the "substrate", and the material to be applied, also called the "sputter target". After the ionization of the argon ions, the argon ions gain kinetic energy under the acceleration of the electric field to bombard the target. Only when the argon ion energy reaches the binding energy of the target electrode (approximately the sublimation heat of the target material), the atomic migration on the target surface can be achieved. When the energy of the bombarding particles exceeds four times the heat of sublimation of the target material, the atoms are pushed out of the lattice position, become gas phase, escape from the target material, and travel toward the material to be plated. This process is called sputtering. For most metals, the sputtering threshold energy is around 10 to 25 eV.
In summary, the basic principles of sputter deposition can be divided into three process steps
1. Gasification of electroplating materials: sputtering;
2. Migration of electroplating atoms, molecules or ions: various reactions occur after atoms, molecules or ions collide;
3. Electroplating atoms, molecules or ions are deposited on the substrate.
Advantages of sputter deposition
1. Good durability, the film obtained by sputtering deposition is sometimes harder and more resistant to corrosion;
2. Wide range of applications, almost all types of inorganic and some organic coating materials can be used for multiple groups of substrates and surfaces with various finishes;
3. Environmental protection. Since the sputter deposition process takes place in a vacuum environment, it is more environmentally friendly than other traditional coating technologies such as electroplating and painting. And the sputtering process will not produce toxic gases such as CO or SO2;
4. It is easy to clean and saves the time and cost of cleaning and polishing general copper (gold) products. It is enough to clean the sputtered film with a soft cloth or glass cleaner;
5. High quality and many choices, the sputtering film has a wide variety of colors, the surface is fine and smooth, rich in metallic luster, and will never fade. Common colors are golden yellow (TiN), bright silver (CrN), purple (TiAlN) and so on.
What types of materials can be used for sputter deposition
Sputtering targets are available in a variety of sizes and materials, including pure metal sputtering targets, ceramic sputtering targets, and alloy sputtering targets. Their purities range from commercial grade 99.9% pure to the highest 99.999% regionally refined ultrapure grade.