Tag: magnetron sputtering

Pros & Cons of 4 Film Manufacturing Methods

The properties of the thin film are determined by the manufacturing method, and different methods have their own advantages and disadvantages. Commonly used preparation processes include magnetron sputtering, chemical vapor deposition, vacuum evaporation, pulsed laser deposition, etc. Among them, magnetron sputtering deposition technology has been widely researched and applied due to its high film formation rate and good uniformity.

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Magnetron Sputtering

The basic principle of the method is that under the action of electric and magnetic fields, the accelerated high-energy particles (A, +) bombard the surface of the target, and after the energy is exchanged, the atoms on the surface of the target escape from the original lattice, and finally, the sputtering particles are deposited on the surface of the substrate and react with oxygen atoms to form an oxide film. The magnetron sputtering process is characterized by excellent optical and electrical properties of the film deposited at low temperatures. In addition, it has the advantages of a high deposition rate, low substrate temperature, good film adhesion, easy to control, and large-area film formation. Therefore, it has become the most researched and widely used film-forming technology in industrial production today as well as a research hotspot in ITO film preparation technology.

Chemical Vapor Deposition

The chemical vapor deposition method is a process in which a gaseous reactant (including a gaseous reactant that becomes a vaporized condensed matter after evaporation) is chemically reacted on the surface of the substrate to deposit a film. This chemical reaction occurring on the surface of the substrate is usually the thermal decomposition and in-situ oxidation of the source material. The reaction system selected by the CVD method must satisfy:

(1) At the deposition temperature, the reactant must have a sufficiently high vapor pressure;
(2) The chemical reaction product must be in a gaseous state except for the solid matter deposited on the substrate;
(3) The vapor pressure of the deposit should be low enough to ensure good adsorption on a substrate having a certain temperature.

Vacuum Evaporation

The vacuum evaporation method is a method in which a raw material of a to-be-formed film in an evaporation vessel is vaporized from a surface to form a vapor stream, and is incident on a surface of the substrate to react with a gas to form a film in a vacuum chamber. A high-quality ITO film can be prepared by the electron beam evaporation deposition method, in which the evaporation substance is In2O3 doped with SnO2, and the mass percentage of SnO2 is 10%. Under suitable process conditions, the deposited film has a minimum resistivity of 4×10-4 Ω•cm and an average transmittance in the visible range of more than 90%.

Pulsed Laser Deposition

The pulsed laser deposition (PLD) process is a very competitive new vacuum physical deposition process developed in recent years. Compared with other processes, it has the advantages of precise control of stoichiometry, synthesis, and deposition, and no requirement for the shape and surface quality of the target, so the surface of the solid material can be processed without affecting the material body.

Stanford Advanced Materials(SAM) is a global sputtering targets manufacturer which supplies high-quality and consistent products to meet our customers’ R&D and production needs. Please visit https://www.sputtertargets.net/ for more information.

What Will Affect The Magnetron Sputtering Voltage?

Magnetic field

Magnetic field influences inversely the sputtering voltage. In other words, when the magnetic field on the surface of the sputtering target increases, the operating voltage of magnetron sputtering will decrease. It happens because the sputter-etched surface of the target gets closer to the strong magnetic field of the permanent magnet behind the target. To be noted, when the magnetic field strength increases above 0.1T, its effect on the sputtering voltage is no longer obvious.

In order to reduce the influence of this factor, the thickness of the sputtered material is not arbitrary, but limited. In general, thicker non-magnetic targets can be used in stronger magnetic fields.

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Material Type

Different target materials also affect the sputtering voltage. Here are examples of ITO, copper, aluminum, titanium, manganese, and chromium target.

Sputtering Target Sputtering Voltage
Indium Tin Oxide (ITO) ≈200V
Copper (Cu)
Aluminum (Al)
Titanium (Ti)		 400~600V
Manganese (Mn)
Chromium (Cr)		 >700V

Gas Pressure

Working gas pressure

Under the condition that various parameters (such as environmental conditions, power control panel parameters, etc.) remain unchanged, the increase of the working gas pressure will reduce the magnetic sputtering voltage.

Reactive gas pressure

On contrary, under the determined environment and constant power source, the increase of reactive gas pressure will result in the increase of magnetic sputtering voltage.

Distance Between Cathode & Anode

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The distance between the cathode and anode in vacuum gas discharge can have a certain effect on the sputtering voltage. If the distance is too large, the internal resistance of the equivalent gas discharge is mainly determined by the plasma equivalent internal resistance. Conversely, if the distance is too small, the internal resistance of the plasma discharge will be small.

When the magnetron target ignited and enters the normal sputtering, if the distance between the cathode and anode is too small, although the sputtering current has reached the process setting value, the target sputtering voltage is still low.

Please visit https://www.sputtertargets.net/ for more information.

Magnetrons & Magnets Used in Magnetron Sputtering

The planar magnetron is an exemplary “diode” mode sputtering cathode with the key expansion of a permanent magnet cluster behind the cathode. This magnet exhibit is organized so that the attractive field on the substance of the target is ordinary to the electric field in a shut way and structures a limit “burrow” which traps electrons close to the surface of the target. This enhances the effectiveness of gas ionization and compels the release plasma, permitting higher presence at the lower gas weight and attaining a higher sputter affidavit rate for Physical Vapor Deposition (PVD) coatings.

Although some distinctive magnetron cathode/target shapes have been utilized in magnetron sputtering processes, the most widely recognized target types are circular and rectangular. Circular magnetrons are all the more regularly found in littler scale “confocal” cluster frameworks or single wafer stations in group instruments. Rectangular Magnetrons are frequently found in bigger scale “in line” frameworks where substrates examine straightly past the focus on some type of carpet lift or transporter.

Color-online-Upper-Illustrations-of-circular-and-rectangular-planar-magnetron
Color-online-Upper-Illustrations-of-circular-and-rectangular-planar-magnetron. Greene, J.. (2017). Review Article: Tracing the recorded history of thin-film sputter deposition: From the 1800s to 2017. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films. 35. 05C204. 10.1116/1.4998940.

Most cathodes – including practically all circular and rectangular ones – have a straightforward concentric magnet design with the middle being one shaft and the edge the inverse. For the circular magnetron, this would be a generally little adjusted magnet in the middle, and an annular ring magnet of the inverse extremity around the outside with a hole in the middle. For the rectangular magnetron, the core one is typically a bar down the long hub (however short of the full length) with a rectangular “wall” of the inverse extremity and the distance around it with a hole in the middle. The crevice is the place the plasma will be, a roundabout ring in the circular magnetron or a lengthened “race track” in the rectangular.

The magnetron works with either an attractive arrangement – the middle could be north and the border might be south, or the other way around. Notwithstanding, in most sputter frameworks, there are various cathodes in reasonably close vicinity to one another, and you don’t need stray north/ south fields structured in the middle of the targets.

Those N/S fields ought to just be on the targets’ confronts, structuring the coveted attractive shafts there. Hence, it is completely attractive to verify all the cathodes in one framework are adjusted the same way, either all north on their borders or all south on their edges. What’s more, for offices with numerous sputter frameworks, it is similarly alluring to make all of them the same so cathodes can securely be traded between the frameworks without agonizing over magnet arrangement.

There are extra contemplations and choices in regard to the magnets. Most target materials are nonmagnetic and in this manner don’t meddle with the obliged attractive field quality. However, in the event that you are sputtering attractive materials, for example, iron or nickel, you will require either higher quality magnets, more slender targets, or both with a specific end goal to abstain from having the surface attractive field adequately shorted out by the attractive target material.

Past that, the magnet’s subtle elements, for example, attractive quality and crevice measurements, might be intended to enhance target material usage or to enhance consistency along the vital pivot of a rectangular target. It is even conceivable to utilize electromagnets rather than perpetual magnets, which can manage the cost of some level of programmable control of the attractive field, yet does, obviously, build many-sided quality and expense.

For more information, please visit https://www.sputtertargets.net/.

Thinning and Coating Process of Mobile Phone Cover Glass

According to the needs of various terminal applications, glass cover panels require various optical glass processing processes such as cutting, edging, drilling, polishing, thinning, chemical strengthening, printing, laser engraving and coating. Today we will introduce the thinning and coating of mobile phone cover glass, which are the most important parts of the whole manufacturing process.

Cover glass thinning process

The glass mentioned in this article is not the 3mm, 5mm, 8mm or even 10mm glass for civil use, but the cover glass for electronic products such as smartphones and tablet computers. Among the glasses currently on the market, the thinnest is 0.15 mm. There is a special thinning process that reduces the thickness of the glass.

Since Steve Jobs started using Corning Gorilla Glass for his iPhones, there emerges a new component for electronic products—cover glass. At the same time, the pursuit of thinner and lighter in the industry is also urging glass manufacturers to make changes to make thinner cover glass.

iPhone cover glass
iPhone cover glass

Currently, the thinnest glass of gorilla can be made 0.4mm, and the Asahi Glass can make 0.2mm glass. In general, people’s expectations for cover glass are nothing more than two:

1. Reduce the space occupied by the glass.

2. Make the glass cover a certain flexibility.

Mobile phone cover glass thinning process

There are not many processes for glass cover thinning: pre-cleaning—etching and thinning—–secondary cleaning——-grinding (single or double sided)—–post-cleaning—–check the package

Pre-cleaning: Remove the stain on the surface of the glass cover. It is one of the key steps affecting the effect of thinning.

Etching and thinning:  using acid and alkali to etch the glass cover achieve the purpose of thinning. The conditions and parameters (time, potash ratio, temperature, etc.) vary from manufacturer to manufacturer, which is the technical secret of the manufacturer.

Secondary cleaning: Clean the residue of the glass cover.

Grinding: To obtain a bright, flat surface. It is one of the key processes for appearance assurance and thickness tolerance control.

Post-cleaning: Clean the remaining grinding powder.

Check the packaging: The standard for the appearance of the glass is different depending on the requirements of the customer.

Mobile phone cover glass thinning treatment

1, multiple pieces of upright soak

2, waterfall flow processing

3, single piece vertical spray

Cover glass coating process

At present, vacuum magnetron sputtering coating technology is a widely used thin film deposition technology. The continuous development of sputtering technology and the exploration of new functional films have enabled the application of magnetron sputtering coating technology to be extended to many productions and scientific research fields.

magnetron sputtering system
magnetron-sputtering-system

magnetron sputtering coating applications

In the field of microelectronics, as a non-thermal coating technology, magnetron sputtering coating technology is mainly applied to materials that are not suitable for chemical vapor deposition or metal organic chemical vapor deposition. Moreover, using magnetron sputtering can obtain a large-area uniform film.

Magnetron sputtering technology is also used in optical films such as antireflection glass, low emissivity glass and transparent conductive glass. In the production of transparent conductive glass, the ITO conductive glass prepared by sputtering has an average transmittance of 90% or more in the visible light range.

In the modern machining industry, the use of magnetron sputtering technology to produce surface functional films, super hard films and self-lubricating films can effectively improve surface hardness, composite toughness, wear resistance and high temperature resistance and chemical stability, thus improve the service life of coated products.

In addition, magnetron sputtering coating technology also plays an important role in the research of high temperature superconducting thin films, ferroelectric thin films, giant magnetoresistive thin films, thin film luminescent materials, solar cells, and memory alloy thin films.

Magnetron sputtering coating advantages

Magnetron sputtering coating technology has become one of the main technologies of the industrial coating due to its remarkable advantages:

(1) Simple operation and easy control. In the coating process, if the sputtering conditions such as working pressure and electric power are relatively stable, the deposition rate is relatively stable.

(2) The deposition rate is high. When depositing most of the metal, especially the high melting point metal and oxide, such as tungsten, aluminum TiO2 and ZrO2 film, it has a high deposition rate.

(3) Low temperature of the substrate. Compared to two-pole sputtering or thermal evaporation, magnetron sputtering reduces the heating of the substrate, which is quite advantageous for achieving the sputter coating of the fabric.

(4) The sputtered film is strong. The sputtered film has excellent adhesion to the substrate and its mechanical strength is also improved.

(5) The sputtered film is dense and uniform. From the photomicrograph, the surface morphology of the sputtered film is fine and uniform.

(6)The sputtered films all have excellent properties. For example, sputtered metal films generally achieve good optical properties, electrical properties, and certain special properties.

(7) Easy to mass produce. The magnetron source can be expanded as required, so large-area coatings are achievable. In addition, sputtering can work continuously, and the coating process is easy to control automatically, so that the industrial assembly line can be realized.

(8) Environmentally friendly. Conventional wet plating produces waste liquid, waste residue, and exhaust gas, causing serious pollution to the environment. The magnetron sputtering coating method has high production efficiency while does not cause environmental pollution.

Please visit https://www.sputtertargets.net/ for more information.