Category: sputtering target

Can Back Target Material be Reused?

Back target materials are an essential component in the sputtering process and play a crucial role in determining the performance of thin film deposition. They serve as a support for sputtering targets, absorbing and dissipating heat generated during sputtering. It is essential to choose a suitable back target material that has good thermal conductivity, stability, and compatibility with the sputtering targets.

Furthermore, it is important to know whether the back target material can be reused or not. In this article, we will discuss the commonly used back target materials in sputtering and analyze whether they can be reused or not.

Analysis of Common Back Target Materials

Oxygen-Free Copper (OFC)

Oxygen-free copper is the most commonly used back target material due to its good electrical and thermal conductivity. Moreover, OFC is also known for its ability to withstand high temperatures. With proper maintenance and care, an oxygen-free copper back target can be reused 10 times or more.

Molybdenum (Mo)

In cases where special conditions of use are required, oxygen-free copper may not serve the purpose as it can get oxidized and warped if high-temperature bonding is necessary. Therefore, molybdenum metal is used as the back target material because of its excellent thermal and electrical conductivity. Moreover, metallic molybdenum is also required as a backing material for certain ceramics and metal targets that do not have a coefficient of thermal expansion that matches oxygen-free copper.

Stainless Steel Tube (SST)

Stainless steel tubes are commonly used as a backing tube for rotating targets as they offer good strength and thermal conductivity and are very economical. They are ideal for use as a backing tube because of their resistance to corrosion and low magnetic permeability.

Can Back Target Materials be Reused?

Most back target materials can be reused, especially with metal indium for the back target, which is easier to clean and reuse compared to other materials. However, if the back target is coated with other adhesives, such as epoxy, it may be necessary to use mechanical treatment to treat the back target surface before reuse.

Conclusion

Choosing the right back target material is crucial for sputtering applications. While oxygen-free copper is the most commonly used back target material, molybdenum, and stainless steel tubes are also widely used for their unique properties.

To get high-quality sputtering targets and evaporation materials, Stanford Advanced Materials (SAM) Corporation is your best option. As a global supplier, we offer a wide range of sputtering targets such as metals, alloys, oxides, and ceramic materials, all of which have high purity. Additionally, we offer target bonding services to meet all of your needs. Visit our website at https://www.sputtertargets.net/ for more information.

Gold Sputtering Target for Semiconductor Coating

Gold sputtering targets can be deposited on a semiconductor chip such as GaAs, GaP, GaN, or the like by sputtering, and can form an ohmic contact film, an electrode, and a wiring film, thereby improving the conductivity and working efficiency of the semiconductor.

The Physical Vapor Deposition Process for Semiconductor Coatings

Physical vapor deposition (PVD) is a widely used method for depositing thin films onto semiconductor substrates such as silicon wafers. The PVD process involves the transfer of material from a sputtering target or an evaporation source to a substrate. This process is carried out in a vacuum environment to prevent contamination and ensure uniform deposition of the material.

PVD is generally divided into two methods based on the principles involved in the deposition: sputtering and evaporation.

Sputtering: How It Works and Its Variations

Sputtering is like throwing stones into a pool of mud, which will splatter a lot of mud and cover the surface of other objects. Sputtering relies on argon plasma to impact the gold sputter target at high speed, thus sputtering the material near the surface of the target and dropping it onto the wafer to form a gold film.

Sputtering is also divided into direct current (DC) sputtering and radio frequency (RF) sputtering depending on the energy source of the plasma excitation. Basically, both methods can be coated with a metal film. The latter is more directed to non-metallic films such as piezoelectric or magnetic materials. The film formed by sputtering has the characteristics of insulation and a high melting point.

Evaporation: Types and Differences from Sputtering

The evaporation method differs from the heating method and is classified into two types: a thermal coater and an E-gun evaporator. The former is to directly put the pellets prepared for melt evaporation on the heating tungsten wire. Once heated, it will adhere to the heated tungsten wire due to the surface tension of the liquid and then be steamed to the periphery (including the wafer). Due to the limited heat resistance of the heated tungsten wire and the limited space for the molten metal, it is only used for low melting point materials, and the film thickness is limited.

The electron gun-type vaporizer uses an electron beam for heating, and the molten and evaporated metal particles are all placed in a graphite or tungsten crucible. When the metal vapor pressure exceeds the critical limit, it begins to slowly evaporate for four weeks (including wafers). The electron gun-type vaporizer can evaporate a metal with a higher melting point and the thickness is not limited.

Advantages and Applications of Gold Sputtering Targets in the Semiconductor Industry

Gold sputtering targets have several advantages that make them a highly desirable material in the semiconductor industry. One of the most significant advantages of gold sputtering targets is their high electrical conductivity, making them ideal for use in forming electrodes, ohmic contacts, and wiring films in semiconductors. Furthermore, gold sputtering targets are known for their excellent adhesion properties, which ensure a strong bond to the substrate surface.

Conclusion

In conclusion, gold sputtering targets are important materials in semiconductor coating applications, and both sputtering and evaporation are commonly used methods for PVD. The choice of method depends on several factors such as deposition rate, film quality, and adherence of the deposited film required for the application. For more information, please visit https://www.sputtertargets.net/.

The Role of Sputtering Targets in Vacuum Sputtering

Introduction to Vacuum Sputtering

Vacuum sputtering is a thin-film technology to deposit thin films and coatings by creating a sub-atmospheric pressure environment and an atomic or molecular condensable vapor source. The basic principle is to make argon (Ar) ions hit the surface of the sputtering target through glow discharge in a vacuum, so that the target atoms overflow and deposit on the substrate to form a thin film.

Most general metal materials use DC sputtering, while non-conductive ceramic materials use RF sputtering. The new sputtering coating equipment uses powerful magnets to accelerate the ionization of argon gas around the target material in a spiral shape, thereby increasing the probability of collision between the target material and argon ions, thereby increasing the sputtering rate.

Characteristics of Sputtering Coating Process

(1) It has a wide range of applications, and can make metal, alloy or insulator materials into thin films.

(2) Under proper setting conditions, multi-component targets can be made into thin films with the same composition.

(3) A mixture or compound of the target substance and gas molecules can be produced by adding oxygen or another reactive gas to the discharge atmosphere.

(4) The target input current and sputtering time are controllable, which is conducive to obtaining high-precision film thickness.

(5) Sputtering coating is more conducive to producing large-area uniform films than other processes.

(6) The sputtered particles are not affected by gravity, and the positions of the target and the substrate can be freely arranged.

(7) The bonding strength between the substrate and the film is more than 10 times that of the general evaporated film, and because the sputtering particles have high energy, the surface of the film is continuously diffused to obtain a hard and dense film. At the same time, high energy allows the substrate to obtain a crystalline film at a lower temperature.

(8) The nucleation density is high at the initial stage of film formation, and an extremely thin continuous film of 10 nm or less can be produced.

(9) The target has a long service life and can be continuously produced for a long time.

(10) The target can be made into various shapes, and with the special design of the machine, it can be controlled better and has the highest efficiency.

How Target Purity Affects Thin Film Quality

Many factors can affect the quality of a thin film, of which the purity of the sputtering target has the greatest impact. If the target material is not pure enough, the impurity particles in the target material will adhere to the surface of the substrate during the sputtering process, causing the film layer in some positions to be weak and peel off. Simply put, the higher the purity of the target material, the better the performance of the film.

For targets with poor thermal conductivity, such as silicon aluminum sputtering targets, the heat transfer is often hindered by impurities in the target. There is a difference between the cooling water temperature used in production and the actual water temperature of the coating line, which leads to cracking of the target during use. Generally speaking, slight cracks will not have a great impact on coating production. However, when the target has obvious cracks, the charge is easily concentrated on the edge of the crack, resulting in abnormal discharge on the surface of the target. Discharging will lead to slag falling, abnormal film formation, and increased product scrapping. Therefore, in the process of target preparation and purity control, it is also necessary to control the preparation process conditions.

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.

 

Application of Molybdenum Target in Mobile Phone LCD Screen

Nowadays, society is full of phubbers, and mobile phones have become the most indispensable thing for the masses. Mobile phone displays are also becoming more and more high-end, such as full-screen design, small bang design, and so on.

Do you know what the important step is in making a mobile phone LCD screen? — Coating, using magnetron sputtering to sputter metal molybdenum from the molybdenum target onto the liquid crystal glass.

As an advanced film material preparation technology, sputtering has two characteristics of “high speed” and “low temperature”. It concentrates ions into a high-speed ion stream in a vacuum to bombard a solid surface. The kinetic energy exchange between the ions and the atoms on the solid surface causes the atoms on the solid surface to leave the target and deposit on the surface of the substrate to form a nano (or micro) film. The bombarded solid is a material for depositing a thin film by sputtering, which is called a sputtering target.

In the electronics industry, molybdenum sputtering targets are mainly used for flat panel displays, electrodes and wiring materials for thin film solar cells, and barrier materials for semiconductors. These are based on its high melting point, high electrical conductivity, low specific impedance, good corrosion resistance, and good environmental performance.

Molybdenum used in components of LCDs can greatly improve the brightness, contrast, color, and life of the LCD. One of the major applications for molybdenum sputtering targets in the flat panel display industry is in the TFT-LCD field.

molybdenum target

In addition to the flat panel display industry, with the development of the new energy industry, the application of molybdenum sputtering targets on thin film solar photovoltaic cells is also increasing. The molybdenum sputtering target mainly forms a CIGS (Copper Indium Gallium Selenide) thin-film battery electrode layer by sputtering. Among them, molybdenum is at the bottom of the solar cell, and is a back contact of the solar cell. It plays an important role in the nucleation, growth, and morphology of the CIGS thin film crystal.

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 is Reactive Sputtering Coating Technology?

At present, reactive sputtering deposition is a well-established sputter coating technology and is widely used for industrial coating deposition to produce thin layers for high-added value products, such as flat panel displays, solar cells, optical components, and decorative finishes.

Definition

In the process of reactive sputtering, a target material is sputtered in the presence of a gas or a mixture of gasses that will react with the target material to prepare a compound film of a predetermined chemical ratio. Reactive sputtering is most often practiced using one or more magnetron sputtering cathodes. Therefore, it is also called reactive magnetron sputtering.

Sputtering Target

Sputtering targets can be divided into metal targets, alloy targets, ceramic targets, etc. Metal sputtering targets can be used to produce compound materials. For example, a titanium sputtering target can be used to produce coatings such as TiO2, TiN, and Ti-O-N. Apart from it, titanium targets can also be used to produce any of the aforementioned different compositions as well as boride and carbide films. Compared with the compound target, the metal target has the advantage of longer service life.

Reactive gases

In most cases, Argon is the main gas used in reactive sputtering as well as other sputter coating methods. It has to be mentioned that the amount of a reactive gas introduced into a process chamber should be strictly controlled in order to either achieve a certain amount of doping or to produce a fully reacted compound. Here is a list of other gasses used in reactive sputtering).

Gasses Uses
Oxygen (O2) deposition of oxide films (e.g. Al2O3, SiO2, TiO2, HfO2, ZrO2, Nb2O5, AZO, ITO)
Nitrogen (N2) deposition of nitride films (e.g. TiN, ZrN, CrN, AlN, Si3N4, AlCrN, TiAlN)
Carbon dioxide (CO2) deposition of oxide coatings
Acetylene (C2H2) deposition of metal-DLC, hydrogenated carbide, carbo-nitride films
Methane (CH4) similar applications as for C2H2

Several reactive gasses can be mixed in order to deposit a multi-component functional thin film. Additional reactive gas is sometimes used to enhance a certain deposition process (e.g. addition of N2 in the SiO2 reactive sputtering process).

Application

Coatings and films produced by Reactive Magnetron Sputtering can be used in a large variety of products such as OLED devices, optical antireflective coatings, and decorative coatings.

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

magnetron sputtering11-9-2

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

magnetron sputtering11-9

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/.

Metal Molybdenum Target Used in Mobile Phone LCD Screen

Nowadays, mobile phones have become the most indispensable thing for the masses. Mobile phone displays are also becoming more and more high-end, such as full-screen designs, small bang designs, and so on.

One of the most important steps in making a mobile phone LCD screen is thin film coating, using magnetron sputtering to sputter the molybdenum target onto the liquid crystal glass to form a Mo thin film. Molybdenum thin films have the advantages of high melting point, high electrical conductivity, low specific impedance, good corrosion resistance and good environmental performance. Compared with the chromium film, the specific impedance and film stress of the molybdenum film are only half of that.

As an advanced film material preparation technology, sputtering has two characteristics of “high speed” and “low temperature”. It concentrates ions into a high-speed ion stream in a vacuum to bombard a solid surface. The kinetic energy exchange between the ions and the atoms on the solid surface causes the atoms on the solid surface to leave the target and deposit on the surface of the substrate to form a nano (or micro) film. The bombarded solid is a material for depositing a thin film by sputtering, which is called a sputtering target.

mobile phone lcd screen

In the electronics industry, molybdenum sputtering targets are mainly used for flat panel displays, electrodes and wiring materials for thin film solar cells, and barrier materials for semiconductors. These are based on its high melting point, high electrical conductivity, low specific impedance, good corrosion resistance, and good environmental performance.

Molybdenum used in components of LCDs can greatly improve the brightness, contrast, color, and life of the LCD. One of the major applications for molybdenum sputtering targets in the flat panel display industry is in the TFT-LCD field.

In addition to the flat panel display industry, with the development of the new energy industry, the application of molybdenum sputtering targets on thin film solar photovoltaic cells is also increasing. The molybdenum sputtering target mainly forms a CIGS (Copper Indium Gallium Selenide) thin-film battery electrode layer by sputtering. Among them, molybdenum is at the bottom of the solar cell, and as a back contact of the solar cell. It plays an important role in the nucleation, growth, and morphology of the CIGS thin film crystal.

For more information, please visit https://www.samaterials.com/.

Solar Thin Film and Its Technical Advantages

Thin-film solar cells refer to thin films with thicknesses ranging from a few nanometers to tens of microns attached to the solar surface, which make thin-film cells lighter in weight. Thin-film solar cells are used in building-integrated photovoltaics as translucent photovoltaic glass materials that can be laminated to windows.

As a second-generation solar technology, thin-film technology is more affordable than the traditional first-generation c-Si technology, but is less efficient. Therefore, in recent years, people have also paid more attention to the development of sputtering materials and thin film coating technology, and are committed to improving the efficiency of thin film technology. And now it has improved significantly. Laboratory cell efficiencies for CdTe and CIGS are now over 21%, better than polysilicon, the main material currently used in most solar photovoltaic systems. And the life expectancy of thin-film solar cells is also extended to 20 years or more.

Thin film solar cells are made by depositing one or more thin layers or thin films of photovoltaic materials on a substrate such as glass, plastic or metal. In the deposition process, the coating source material used are usually sputtering targets or evaporation materials. Commonly used thin-film solar cell categories include cadmium telluride (CdTe) thin films, copper indium gallium selenide (CIGS) thin films, and gallium arsenide (GaTe) thin films.

The target materials corresponding to the three thin films mentioned above are important materials for the thin film coating of solar cells. Among them, cadmium telluride targets account for 50% of the solar market. On a life cycle basis, CdTe PV has the smallest carbon footprint, lowest water usage, and shortest energy payback time of all solar technologies. With an energy payback period of less than a year, CdTe can reduce carbon emissions faster without short-term energy shortages.

The CIGS sputtering target is composed of four metal elements, namely copper (Cu), indium (In), gallium (Ga) and selenium (Se), and it is also one of the representatives of commonly used targets in the solar industry. CIGS thin film has the advantages of strong light absorption, good power generation stability and high conversion efficiency, which can enable solar cells to generate electricity for a long time during the day and generate a large amount of electricity. CIGS has great advantages in photovoltaic building-integrated applications. At the same time, with the improvement of CIGS conversion efficiency, the self-sufficiency rate of CIGS as a photovoltaic building power supply built with glass curtain walls is also increasing.

GaAs thin-film solar cells have an efficiency of up to 28.8%, which is considered the highest efficiency of all thin films. Gallium arsenide is also resistant to damage from moisture, radiation and UV light. These properties make GaAs thin films an excellent choice for aerospace applications with increased UV and radiation.

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

Classification of Molybdenum Target Materials

Molybdenum sputtering targets perform the same as their source material (pure molybdenum or molybdenum alloy). Molybdenum is a metallic element mainly used in steel, where it improves the strength, hardness, weldability and toughness of alloys, as well as high temperature and corrosion resistance. Molybdenum targets are one of the important sputtering materials and are used in aerospace, semiconductor, solar and many other applications.

Different Shapes of Sputtering Target
Different Shapes of Sputtering Target

Classify by Shape of Molybdenum Target

According to the shape of the target, the molybdenum target can be divided into square molybdenum target, circular molybdenum target, molybdenum plate target, rotatory molybdenum target, and molybdenum tube target.

The square molybdenum target has the characteristics of high melting point, high electrical conductivity, low impedance, good corrosion resistance and good environmental performance. It is the most widely used planar molybdenum target.

The circular molybdenum target, or the disc molybdenum target, also has a wide range of applications, which can form films on various types of substrates, and these films can be widely used in electronic components and electronic products.

Molybdenum plate target common thickness is 0.09 inch ~ 3 inch and the surface shows silver-gray metallic luster. Common Specifications (mm) is BCM = 9.9 (0.3-10) (60-400) 800 or bigger.

The rotatory molybdenum target is a rotatable sputtering target that is usually cylindrical and has a fixed magnet so that it will rotate at a low speed during operation.

The length of the molybdenum tube target is generally ≤3000mmm, and the outer diameter is ≤250mm. The wall thickness is 3-25 mm and the flatness is 0.1 mm. In addition, its shape is tubular and the surface shows a silver metallic luster.

Classify by Applications of Molybdenum Target

According to its application, the molybdenum target can be divided into the X-ray molybdenum target, the coated molybdenum target, and etc. Stanford Advanced Materials offers a wide range of high performance, high quality molybdenum targets.

Coated molybdenum target has good properties, including excellent high temperature performance, high temperature physical strength, high elastic modulus, excellent thermal conductivity and corrosion resistance and other properties, so commonly used in the field of coatings, as coating materials.

X-ray molybdenum targets are commonly used in the medical field for breast examination of women. X-ray mammography as a non-invasive method can more fully and accurately reflect the structure of the entire breast.

If you have any interest in molybdenum metal targets, please visit our website at https://www.sputtertargets.net/.