The basic way and material type of PVD coating

PVD (Physical Vapor Deposition) technology is one of the main technologies for the preparation of thin film materials. Under vacuum conditions, some materials are vaporized into gaseous atoms and molecules or partially ionized into ions by Physical methods, and the process of low-pressure gas (or plasma) is adopted.  The technology of depositing thin film materials with special functions such as antireflection, reflection, protection of electric and magnetic conductivity, insulation, corrosion resistance, oxidation resistance, radiation resistance and decoration on the surface of substrate materials.  The substance used to prepare the thin film material is called PVD coating material.  Sputtering coating and vacuum evaporation coating are the two most popular PVD coating methods.

Sputtering coating  

Sputtering target material has the characteristics of high purity, high density, multi - component and uniform grain, and generally consists of target blank and backplane.  The target blank belongs to the core part of sputtering target material and is the target material of high speed ion beam bombardment.  After the target is impacted by ions, the surface atoms are sputtered out and deposited on the substrate to form electronic films.  Due to the low strength of high-purity metal, the sputtering target needs to complete the sputtering process in a high voltage and high vacuum environment.  The sputtering target blank of ultra-high purity metal needs to be joined with the backplane through different welding processes. The backplane mainly plays the role of fixing the sputtering target and needs to have good electrical and thermal conductivity.

According to the use of different raw materials, sputtering target can be divided into metal/non-metal single target, alloy target, compound target, etc..  Sputtering coating process, good repeatability, film thickness can be controlled, can be obtained in large area on the substrate material thickness of thin film, the preparation of the thin film has high purity, good compactness and strong bonding force with substrate material advantages, has become one of the main technology of preparation of thin film materials, various types of sputtering film materials have been widely used, therefore,  The demand for sputtering target, a functional material with high added value, is increasing year by year. Sputtering target has also become the largest PVD coating material in the current market.

Ultra-high purity metal and sputtering target is an important part of electronic materials, sputtering target industry chain mainly includes metal purification, target manufacturing, sputtering film and terminal application, among which, target manufacturing and sputtering film link is the key link in the whole sputtering target industry chain.  

Upstream metal purification is mainly from the nature of key metal ore purification, general metal can reach 99.8% purity, sputtering target needs to reach 99.999% purity.  

In the process of target material manufacturing, process design should be carried out according to the performance requirements of downstream application fields, and then repeated plastic deformation and heat treatment should be carried out to control key indicators such as grain size and grain orientation, and then water cutting, machining, metallization, super testing, ultrasonic cleaning and other processes should be carried out.  

The manufacture of sputtering target involves many and delicate processes. The management of process flow and the level of manufacturing technology will directly affect the quality and yield of Sputtering target.  

This link is in the sputtering target material industry chain to the production equipment and technology requirements of the highest link, the quality of sputtering film has an important impact on the quality of downstream products.

Vacuum evaporation coating  

Vacuum evaporation coating refers to a kind of technology to obtain thin films by heating and evaporating certain substances on the surface of substrate materials under vacuum conditions.  The vaporized material is known as the evaporation material.  Evaporative coating was first proposed by M. Faraday in 1857. After more than 100 years of development, it has become one of the mainstream coating technologies.  

Vacuum evaporation coating system is generally composed of three parts: vacuum chamber, evaporation source or evaporation heating device, placing substrate and heating device for substrate.  In order to evaporate the material to be deposited in a vacuum, containers are needed to support or hold the vaporizers and to provide evaporative heat to reach a temperature high enough to generate the desired vapor pressure.

Vacuum evaporation coating technology has the characteristics of simple and convenient, convenient operation, fast film forming speed and so on, is widely used in the coating technology, mainly used in optical components, LED, flat panel display and semiconductor separator coating.  Vacuum coating materials can be divided into metal/non-metal particles according to the chemical composition of vaporizers, oxide vaporizers, fluoride vaporizers, etc.  

Type of evaporation material  

Metallic and nonmetallic particles  

Aluminum, nickel, copper, silver, titanium, silicon, vanadium, magnesium, tin, chromium, indium, silver-copper, gold, microcrystalline silver powder, etc.  

Oxides  

Titanium tantalum alloy, zirconium titanium alloy, silicon aluminum alloy, aluminum oxide, zirconium dioxide, titanium pentaoxide, quartz ring, quartz chip, erbium oxide, lanthanum titanate, etc.

Fluorides  

Magnesium fluoride, dysprosium fluoride, lanthanum fluoride, etc.

The main process of steam plating material includes mixing, raw material pretreatment, molding, sintering and testing.  The prepared raw materials are mixed mechanically to achieve uniform dispersion (mixing), and then treated at room temperature or high temperature (raw material pretreatment) to improve the purity of the material, refine the particle size, stimulate the reactivity of the material, and reduce the sintering temperature of the material.  The material is then mechanically processed to the desired specifications (molding).  After molding, the material is sintered at high temperature, so that the solid particles of the ceramic green billet bond with each other, and finally become a dense polycrystalline sintered body with a certain microstructure (sintering).  After the evaporation coating material is produced, the evaporative coating equipment is used to test the performance of the material and check whether the product performance indicators are qualified.

Vacuum coating material process  

Raw material powder -- batching -- mixing -- raw material pretreatment -- molding -- pre-firing -- vacuum sintering -- sorting -- vacuum packaging  

Comparison of sputtering coating and evaporation coating

Sputtering coating process, good repeatability, film thickness can be controlled, can be obtained in large area on the substrate material thickness of thin film, the preparation of the thin film has high purity, good compactness and strong bonding force with substrate material advantages, has become one of the main technology of preparation of thin film materials, various types of sputtering film materials have been widely used, therefore,  The demand for sputtering target, a functional material with high added value, is increasing year by year. Sputtering target has also become the largest PVD coating material in the current market.  

Evaporation coating is simple and convenient, easy to operate and fast film forming speed.  In terms of manufacturing process, the manufacturing complexity of evaporation materials is much lower than that of sputtering target materials, and evaporation coating is often used for small size substrate materials.