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Four application areas of high-purity sputtering targets

The application fields of high-purity sputtering targets mainly include semiconductors, panels, photovoltaics and optical devices. Sputtering coating processes are required in the production processes of integrated circuits, flat panel displays, solar cells, information storage, tool modification, optical devices, and high-end decorative articles, and the application fields of sputtering targets are very broad. The industries that use a large amount of target materials mainly include integrated circuits, flat panel displays, solar cells, magnetic recording media, and optical devices. Among them, high-purity sputtering targets are mainly used in fields that require higher material purity and stability, such as integrated circuits, flat panel displays, solar cells, magnetic recording media, smart glass and other industries.

Semiconductor chips have extremely high technical requirements for sputtering targets and are extremely expensive. The purity and technical requirements for target materials are higher than other application fields such as flat-panel displays and solar cells. The semiconductor chip sets extremely harsh standards for the purity of the metal material of the sputtering target, the internal microstructure, etc. If the sputtering target contains too much impurity, the formed film will not meet the electrical performance required for use, and Particles are easily formed on the wafer during the sputtering process, causing short circuit or damage to the circuit, which will seriously affect the performance of the film. Generally speaking, chip manufacturing has the highest requirements for metal purity of sputtering targets, usually 99.9995% (5N5) or more. Flat panel displays and solar cells require 99.999% (5N) and 99.995% (4N5) respectively.

Semiconductor target: used for wafer conductive barrier layer and packaging metal wiring layer production
Sputtering targets are needed in the two major links of wafer production and chip packaging. In the wafer manufacturing process, the targets are mainly used to adhere to the conductive layer, barrier layer and metal gate of the wafer, and in the chip packaging process , The target is used to generate metal materials such as the metal layer under the bump and the wiring layer. Although the target material is not used in the field of wafer manufacturing and chip packaging, according to SEMI statistics, the cost of the target material in the wafer manufacturing and packaging process is about 3%, but the quality of the sputtering target directly affects The uniformity and performance of the conductive layer and the barrier layer affect the transmission speed and stability of the chip. Therefore, the target is one of the core raw materials for semiconductor production.

In the process of wafer production, semiconductor sputtering targets are mainly used for the production of wafer conductive layers and barrier layers and metal gates. Metals such as aluminum, titanium, copper, and tantalum are mainly used. The round production is similar, mainly copper, aluminum, titanium, etc. Among them, the metal targets used for the conductive layer of the wafer are mainly aluminum and copper targets, and the metal targets used for the barrier layer are mainly tantalum and titanium targets. The barrier layer mainly has two functions. On the one hand, it is blocking and insulating to prevent conduction. The layer metal diffuses into the silicon, which is the main material of the wafer, and on the other hand acts as adhesion to bond the metal and silicon material. Generally speaking, wafers above the 110nm technology node use aluminum and titanium as the thin film materials for the wires and barrier layers, and the wafers below 110nm use copper and tantalum materials as the thin film materials for the wires and barrier layers. As the wafer process shrinks In the future, the proportion of copper targets, tantalum targets and titanium targets for making metal gates will continue to increase.

Panel target: mainly used to make ITO glass and touch screen electrodes
The flat panel display industry mainly uses target sputtering coating in the production of display panels and touch screen panels. It is mainly used to make ITO glass and touch screen electrodes. The largest amount is indium tin oxide (ITO) target. Then there are metal targets such as molybdenum, aluminum and silicon. 1) In the production process of flat panel display panels, the glass substrate must undergo multiple sputtering coatings to form ITO glass, and then coating, processing and assembly for the production of LCD panels, PDP panels and OLED panels, etc.; 2) Touch screen production The ITO glass needs to be processed, coated to form electrodes, and then assembled with protective screens and other components. The silicon dioxide film formed by the sputtering of silicon target material mainly plays the role of increasing the adhesion and flatness of the glass and the ITO film, surface passivation and protection, etc. The etching of the MoAlMo (molybdenum aluminum molybdenum) target material mainly acts as the metal lead The role of bridging. In addition, in order to realize the functions of anti-reflection and anti-shadow of flat panel display products, the coating of the corresponding film layer can also be added in the coating process.

Photovoltaic targets: used to form the back electric level of solar thin film cells
The target is mainly used to generate the back electrode of the solar thin film battery, and the sputtering target is rarely used in the crystalline silicon solar battery. Solar cells mainly include crystalline silicon solar cells and thin-film solar cells. Crystalline silicon solar cells have high conversion efficiency, stable performance, and various industrial links are relatively mature, occupying a dominant position in the solar cell market. According to different production processes, crystalline silicon solar cells can be divided into wafer-coated solar cells and PVD process high-conversion silicon wafer solar cells. Among them, the production of silicon wafer-coated solar cells does not use sputtering targets. Mainly used in the field of solar thin film batteries.

The back level of solar thin film battery formed by target sputtering coating has three main uses: first, it is the negative electrode of each single cell; second, it is the conductive channel of each battery in series; third, it can increase solar energy The reflection of light by the battery. Sputtering targets for solar thin-film batteries are mainly in the shape of square plates, and the purity requirements are not as high as those for semiconductor chips, which are generally above 99.99%. At present, the more commonly used sputtering targets for the preparation of solar cells include aluminum targets, copper targets, molybdenum targets, chromium targets, ITO targets, AZO targets (aluminum oxide zinc) and so on. Among them, aluminum target and copper target are used for conductive film, molybdenum target and chromium target are used for barrier film, and ITO target and AZO target are used for transparent conductive film.

Optical device target: use optical coating to change light wave transmission characteristics
Optical devices need to rely on optical coating to form one or more layers of dielectric film and metal film. The film system composed of the two changes the characteristics of light wave transmission, including light transmission, reflection, absorption, scattering, polarization and phase change , Mainly used target materials such as silicon, niobium, silicon dioxide, and tantalum. The application range of optical devices is very wide, mainly including smart phones, car lenses, security monitoring equipment, digital cameras, optical disc players, projectors, etc. High-end application products include aerospace monitoring lenses, biometric identification equipment, DNA sequencing in life sciences, etc. Optical components and optical lenses required for equipment, medical inspection equipment lenses, semiconductor testing equipment, large-field projection lenses (such as IMAX), 3D printers and other equipment.

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