Titanium target is the target material bombarded by high-speed charged particles. Titanium target is one of the main materials for preparing thin films, which is mainly used in integrated circuits, flat panel displays, solar cells, recording media, smart glass, etc., with high requirements for material purity and stability.
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Titanium target parameters
Material purity 99.90% Relative density of material 100% Target shape Circular target Rotating target Rectangular target Splicing target Maximum size 200mm Ø200×60mm 200×200mm 200mm×mm(1) Purity
Purity is one of the main performance indicators of the target, because the purity of the target has a great impact on the performance of the film. However, in practical applications, the requirements for the purity of the target are also different. For example, with the rapid development of the microelectronics industry, the silicon chip size has grown from 6 “, 8” to 12 “, and the wiring width has been reduced from 0.5 um to 0.25 um, 0.18 um or even 0.13 um. Previously, 99.995% of the target purity can meet the process requirements of 0.35 um IC, while the target purity is required to be 99.999% or even 99.% for the preparation of 0.18 um lines.
(2) Impurity content
Impurities in the target solid and oxygen and water vapor in the pores are the main pollution sources of the deposited films. Different target materials have different requirements for different impurity content. For example, pure aluminum and aluminum alloy targets used in the semiconductor industry have special requirements for alkali metal content and radioactive element content.
(3) Density
In order to reduce the porosity in the target solid and improve the performance of the sputtered film, the target is usually required to have a high density. The density of the target affects not only the sputtering rate, but also the electrical and optical properties of the film. The higher the target density, the better the film performance. In addition, increasing the density and strength of the target can better withstand the thermal stress in the sputtering process. Density is also one of the key performance indicators of the target.
(4) Grain size and grain size distribution
Usually, the target is polycrystalline, and the grain size can be from micrometer to millimeter. For the same target, the sputtering rate of targets with fine grains is faster than that of targets with coarse grains; The thickness distribution of the films deposited by target sputtering is more uniform when the grain size difference is small (uniform distribution).
TA0、TA1、TA2、TA9、TA10、ZR2、ZR0、GR5、GR2、GR1、TC11、TC6、TC4、TC3、TC2、TC1.
Plastic deformation, heat treatment and grain orientation control: process design shall be carried out according to the performance requirements of downstream application fields, and then repeated plastic deformation and heat treatment shall be carried out. Key indicators such as grain and grain orientation shall be accurately controlled, and then welding, machining, cleaning and drying, vacuum packaging and other processes shall be carried out. Target manufacturing involves a wide range of processes, high technical threshold, large equipment investment, and relatively few enterprises with large-scale production capacity. The manufacturing methods of target materials mainly include smelting method and powder metallurgy method. The melting method mainly includes vacuum induction melting, vacuum arc melting, vacuum electron beam melting and other methods. The melted ingots are prepared into targets through mechanical processing. The targets obtained by this method have low impurity content, high density, can be large-scale, and have no internal pores. However, if the melting point and density of the two alloys differ greatly, uniform alloy targets cannot be formed. Powder metallurgy method mainly includes hot isostatic pressing method, hot pressing method and cold pressing sintering method. The target material is obtained by mixing and sintering various raw materials. The advantages of this method are that the target material composition is relatively uniform, the mechanical properties are good, and the disadvantages are that the oxygen content is high.
Classification of target manufacturing process
Widely used in decorative coating, wear-resistant coating, electronic industry CD, VCD and other types of optical discs and various magnetic disc coating.
Tungsten titanium (W-Ti) films and alloy films based on tungsten titanium (W-Ti) are superalloy films, which have a series of irreplaceable excellent properties. Tungsten has high melting point, high strength and low thermal expansion coefficient. W/Ti alloy has low resistance coefficient, good thermal stability and oxidation resistance. For example, all kinds of devices need metal wiring that can conduct electricity, such as Al, Cu and Ag, which have been widely used and studied. However, the wiring metal itself is easy to oxidize, react with the surrounding environment, and has poor adhesion with the dielectric layer. It is easy to diffuse into the substrate materials of devices such as Si and SiO2, and will form metal and Si compounds at low temperatures, acting as impurities, which greatly reduces the performance of devices. However, W-Ti alloy is easy to be used as a diffusion barrier layer for wiring due to its stable thermo mechanical properties, low electron mobility, high corrosion resistance and chemical stability, especially suitable for use in high current and high temperature environments.
Titanium as a raw material can be made into titanium sputtering targets by several methods. They are widely used in electronics, information industry, home decoration, automobile glass manufacturing and other high-tech fields. In these industries, titanium targets are mainly used for surface panel displays of coated integrated circuits, flat panels and other components, or for decoration and glass coating.
Different industries have different requirements for titanium targets. Let’s take the titanium circuit as an example. Generally, we use the following performance evaluation indicators to determine whether the sputtering target meets the requirements:
As shown in the above table, the requirements for titanium sputtering targets for non integrated circuits and integrated circuits are different. Generally speaking, integrated circuits have high requirements for coating materials, such as higher purity, smaller grain size and more accurate size accuracy. This is just an example, but it reveals that different industries have different requirements for titanium targets. When looking for titanium targets for projects, make sure you know the exact specifications of the products you need, which will help save time and money.
It can be seen from the above table that the purity requirements of titanium target for integrated circuits are mainly greater than 99.995%, which is higher than the purity used in non integrated circuits.
Flat panel display includes liquid crystal display (LCD), plasma display (PDP), electroluminescent display (EL) and field emission display (FED). Sputtering coating technology is usually used to deposit thin films of flat panel displays. Al, Cu, Ti and Mo are the main metal sputtering targets for flat panel displays. The purity of titanium target used for flat panel display usually needs to be greater than 99.9%.
Phase I:
Early chip foundries had high profit margins. They mainly use 100-150mm magnetron sputtering machine with small power. The sputtering film is thick and the chip size is large. At that time, the titanium target materials for integrated circuits were mainly 100-150mm monomer and composite target.
Phase II:
In the second stage, according to Moore’s Law, the line width of the chip narrows. In order to increase profits, the chip foundry increased the sputtering power of the equipment, mainly using 150-200mm sputtering equipment. This requires increasing the size of the target while maintaining high thermal conductivity, low price and certain strength. During this period, titanium target is mainly composed of aluminum alloy back plate diffusion welding and copper alloy back plate brazing and welding.
The third stage:
In the third stage, with the development of integrated circuits, the width of chip lines is further narrowed. At this time, the chip foundry mainly uses a 200-300mm sputtering machine, which is more strict with the target. During this period, Ti target is mainly made of copper alloy back plate by diffusion welding.
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Sputtering is a cornerstone of physical vapor deposition (PVD) and stands at the forefront of materials science and advanced manufacturing. This versatile technique plays a pivotal role in the deposition of thin films onto substrates with plenty of advantages and limitations. In this article, we will delve into the world of sputtering, uncovering its principles, strengths, and areas where it faces challenges
Sputtering is a fundamental process in materials science and manufacturing that involves the deposition of thin films onto surfaces. It works by bombarding a target material with high-energy ions, typically using an inert gas like argon in a vacuum chamber. When the ions collide with the target, they dislodge atoms or molecules from the surface, which then condense on a substrate to form a thin film.
Figure 1. The Sputtering Process
This technique offers several advantages, including precise control over film thickness, high material purity, and the ability to deposit a wide range of materials. It is widely used in industries such as microelectronics, optics, and coating technology to create thin films with specific properties for various applications. Sputtering plays a crucial role in producing everything from semiconductor devices to optical coatings on lenses and mirrors. Its versatility and ability to deposit high-quality films make it a valuable tool in modern manufacturing and research.
Indeed, sputtering is a technique that brings a multitude of advantages to the realm of thin film deposition. Here are some notable examples.
However, sputtering is not without its challenges, and a comprehensive understanding of both its strengths and limitations is crucial for harnessing its full potential.
Related reading: Advantages and Disadvantages of Ion Beam Sputtering
In summary, sputtering is a versatile and widely used thin film deposition technique with several advantages, including high purity, precise control, and uniformity. Yet, it also has limitations, such as slower deposition rates, high equipment costs, and heat sensitivity. The choice of deposition technique depends on the specific requirements of the application and the properties of the materials involved.
Stanford Advanced Materials (SAM) is a leading supplier of a variety of sputtering targets and evaporation materials. Customization is also welcome. Send us an inquiry if you are interested.
Reference:
[1] Pujahari, R. (, June 8). Solar cell technology. ScienceDirect. Retrieved September 8, , from https://www.sciencedirect.com/topics/chemical-engineering/sputter-deposition