With the high-speed iteration of semiconductor, OLED/LCD flat panel display, photovoltaic new energy, aerospace high-end manufacturing industry, PVD physical vapor deposition technology has become the core process of precision thin film preparation. Tungsten sputtering target with extreme thermal stability, mechanical strength and electrical properties, become an irreplaceable core material in high-end precision coating scene. As a complete guide to tungsten sputtering targets, this article will comprehensively disassemble the core advantages, technical parameters, category classification and production process of tungsten targets.

What is tungsten sputtering target?

Tungsten sputtering target is a high-purity, high-density tungsten metal blank made by powder metallurgy, precision molding and CNC machining. It is the core source material for magnetron sputtering and PVD processes.  Its core function is to form uniform and dense tungsten functional films on the surface of the substrate by stripping atoms through plasma bombardment in vacuum environment.

Different from ordinary tungsten materials, PVD sputtering grade tungsten targets have extremely strict requirements on purity, density, grain uniformity, surface flatness and size tolerance.  Each index will directly affect the purity, adhesion, uniformity and stability of the coating, which is the core basic material for high-end film manufacturing.

According to different process requirements, tungsten sputtering target can be divided into pure tungsten target, tungsten alloy target, tungsten compound target, suitable for semiconductor, optical, wear-resistant coating and other different application scenarios, is currently one of the best comprehensive performance of high-end PVD coating target category.

Unique advantages of Tungsten sputtering target

Extreme high temperature thermal stability

Tungsten is currently known to have the highest melting point of the metal, melting point as high as 3422℃, far more than all conventional sputtering metal materials.  In the process of high-power magnetron sputtering, the target surface will continue to withstand the high temperature caused by plasma bombardment, and conventional metals are easy to melt, deform and ablate.

Tungsten target will not melt, deform, crack and other problems under high temperature environment, can maintain long-term structural stability, adapt to continuous, high-power industrial mass production process, greatly improve process stability.

Tungsten has a very low coefficient of thermal expansion, so it will not produce stress deformation due to thermal expansion and contraction under the condition of rapid temperature rise and fall.  Perfect solution to the common problems of film peeling, target cracking, coating unevenness, etc. in high-end coating.

excellent mechanical properties

Tungsten metal density up to 19.3g/cm³, high hardness, tensile strength, with strong impact resistance, wear resistance.  Under the continuous plasma ion bombardment, the target surface erosion is uniform, and local rapid loss, pits, spalling and the like do not occur.  Stable mechanical properties allow tungsten targets to maintain a smooth bombardment surface for a long time, ensuring that the deposition rate and film thickness of each coating are highly consistent.

Stable electrical and chemical properties

Tungsten metal has excellent thermal conductivity and electrical conductivity, and the deposited tungsten film has excellent electrical conductivity, which can be used as the core functional layer of chip interconnection lines, electrodes, conductive contacts, etc. to meet the electrical conductivity requirements of microelectronic devices.

Under high temperature conditions, tungsten has a very low saturated vapor pressure, and there will be no irregular volatilization and impurity precipitation.  It can avoid secondary pollution during the coating process from the source and ensure the quality requirements of high purity and low defects of the film.

In addition, tungsten target is suitable for reactive sputtering process, which can stably generate functional compound films such as tungsten nitride and tungsten oxide in nitrogen and oxygen atmosphere to meet the requirements of optical, semiconductor, protective coating and other diversified scenarios.

Technical parameters of tungsten sputtering target

Purity grade

Tungsten sputtering target purity is divided into three mainstream grades, different grades correspond to different application scenarios, on-demand selection can balance quality and cost, avoid excessive procurement or insufficient precision.

3N5 grade (99.95% purity): suitable for general scientific research experiments, conventional wear-resistant coatings, general optical coatings and other scenes with low sensitivity to impurities, high cost performance.

4N grade (99.99% purity): suitable for conventional display panels, ordinary microelectronic devices, photovoltaic coatings and other high-end scenes, taking into account quality and cost.

5N grade (99.999% purity): extremely low impurity content, must be used in chip manufacturing, advanced RF devices, precision microelectronics and other core scenarios, to prevent device failure caused by impurities.

Density

The theoretical density of tungsten target is 19.25g/cm³, and the industry standard is relative density ≥99%. The density of high-end semiconductor target should be ≥99.5%, approaching the full dense state.  There are few pores in the high-density target, and no gas release occurs during sputtering.  It can effectively avoid bubbles, pinholes and particle defects in the film and ensure the uniformity of the coating.

Tolerance of size and accuracy

Tungsten sputtering targets are divided into two main forms: planar targets and rotating targets.

The diameter of flat circular tungsten sputtering target covers 1 inch, 2 inches, 3 inches, 4 inches, 6 inches, 8 inches to 14 inches, and the thickness is 3.175mm and 6.35mm. It can also be customized to thicker specifications of more than 1mm according to requirements.

Rectangular planar target maximum length up to 32 inches, width of more than 12 inches, thickness ≥1mm, suitable for large planar sputtering chamber.

Rotary target can customize large diameter, long size pipe, suitable for large-area continuous coating production line.

The size tolerance of industrial grade targets is controlled within ±0.010 inches, and the tolerance of high-end precision targets can be further tightened. Surface roughness Ra<1.6μm, extremely high finish, can minimize particle generation.

Types of Tungsten sputtering target you should know

Tungsten sputtering target can be divided into multiple categories according to shape structure, material composition and welding method. The equipment, process and scene adapted to different categories vary greatly. Accurate classification is the basis for selection.

Classification by external structure

Plane target is the most widely used and versatile target type, including circular, square, rectangular, annular and other conventional shapes, simple structure, wide adaptability.

Flat targets are mainly suitable for laboratory research and development, small and medium-sized vacuum sputtering chambers, conventional magnetron sputtering guns, suitable for small batches, multi-category, high-precision coating production and scientific research scenarios, low procurement cost, easy replacement.

Rotary cylindrical target is tubular structure, continuous rotation in the process of work, uniform plasma bombardment on the surface, uniform wear without dead corners, material utilization up to 70%-90%, much higher than flat target.

Rotary targets are mainly used in large-area, large-batch continuous mass production scenarios such as glass coating, flat panel display, photovoltaic panels, etc., which can greatly reduce the frequency of downtime replacement and improve the overall efficiency of production lines.

Classification by Material Composition

Pure tungsten sputtering target material (W) has high purity and stable performance, which is the most basic target category.  Mainly used for depositing pure tungsten conductive film, barrier film, widely used in semiconductor, microelectronics, conventional conductive coating scene.

Tungsten alloy sputtering target material with tungsten titanium (W-Ti), tungsten molybdenum (W-Mo) as the core representative, through the proportion of alloy elements to optimize material properties.  Among them, 90/10 tungsten titanium target is a semiconductor classic diffusion barrier material, which can effectively block metal ion diffusion.

Tungsten compound sputtering target materials include tungsten oxide (WO), tungsten carbide (WC), tungsten disulfide (WS $>), tungsten silicide (WSi $>), etc., which are used for optical electrochromic, wear protection, solid lubrication and semiconductor contact layer coating.

Customized tungsten sputtering targets

For special equipment and special process requirements, we can customize tungsten target with groove, chamfer, thread and special curved surface structure. At the same time, we can customize special surface treatment process to adapt to non-standard sputtering equipment and special coating process.

Tungsten sputtering target manufacturing process

Tungsten sputtering target can not be produced by traditional melting and casting process. The core production process is powder metallurgy, which can accurately control purity, density and microstructure to ensure high-end quality of target.  COMBAT deep-ploughed tungsten sputtering target manufacturing, set up tungsten product factory in China, with complete production line stable supply of tungsten sputtering target.

Step 1: hydrogen reduction preparation of high purity tungsten powder.  Tungsten trioxide is used as raw material to prepare ultrafine, high-purity and low-oxygen tungsten powder by high temperature hydrogen reduction process, and the purity of raw material is controlled from the source.

Step 2: Homogenize the powder in inert atmosphere.  Powder mixing and ball milling are carried out under argon inert environment to avoid powder oxidation.  Make the powder particle size and composition highly uniform, laying the foundation for subsequent molding.

Step 3: cold isostatic pressing.  CIP cold isostatic pressing process was used to compact the powder into compact, regular green body with uniform density, no delamination, no crack and good workability.

Step 4: High temperature vacuum sintering.  The green body is placed in a vacuum or hydrogen sintering furnace and sintered at a high temperature of 1400 - 2000 ° C for a long time. The initial densification of the green body is achieved through atomic diffusion, and the overall density is greatly increased.

Step 5: hot isostatic pressing densification.  HIP hot isostatic pressing process was adopted to eliminate the micropores in the green body, and the relative density was increased to more than 99.5%, achieving nearly full dense state.

Step 6: Thermoforming.  Through forging, hot rolling, extrusion and other thermal processing technology, refined grain, uniform structure, eliminate internal stress, adapt to plane, rotation of various target shapes.

Step 7: precision machining polishing. CNC precision machining, grinding, polishing process, strict control of size tolerance and surface roughness, removal of machining burrs, scratches, to achieve the coating process standards.

Step 8: back plate welding and full inspection.  Complete copper aluminum back plate welding as required, and then carry out density detection, impurity analysis, metallographic detection, ultrasonic flaw detection and size calibration. Qualified products can be delivered from factory.

Industrial applications of tungsten sputtering targets

Tungsten targets of different categories and parameters correspond to different industry scenarios. Accurate matching of targets can maximize material performance and improve production yield and economic benefits.

Semiconductors and Microelectronics

The semiconductor industry is the core application scenario of 5N ultra-high purity tungsten target.  Pure tungsten and tungsten-titanium alloy targets are mainly used as diffusion barriers for chips, which can effectively block the mutual diffusion of copper, silicon and other materials and ensure the stability of chip structure.

At the same time, tungsten thin film can be used to prepare chip interconnection wires, electrode contacts and transistor conductive layers. With high conductivity, high stability and high temperature resistance, it can meet the working requirements of chip high precision and high reliability.

LCD/OLED flat panel display industry

Tungsten target is used to prepare TFT thin film transistor conductive layer and circuit layer in the manufacture of liquid crystal and organic light-emitting display panels to ensure screen clarity, contrast and display uniformity.

Tungsten oxide thin films prepared by reactive sputtering can be used as electrochromic and transparent conductive functional layers, widely used in smart dimming glass and high-end display devices, and meet the needs of large-area mass production coating.

RF communication acoustic devices

Tungsten sputtering film is the core functional material of SAW and BAW bulk acoustic wave filters.  This type of filter is widely used in mobile phones, base stations, and RF communication equipment, and is responsible for signal filtering and frequency regulation.

Tungsten thin film has high stability and high precision characteristics, which can ensure accurate frequency, stable performance and long service life of communication devices. It is a key basic material for 5G/6G communication devices.

Optical Coating and Photovoltaic New Energy

Tungsten and tungsten oxide target can be used to prepare optical reflection film, antireflection film, passivation film, protective film, used for lens, optical instruments, precision lens coating production, improve the performance of optical devices.

In photovoltaic industry, tungsten target is used for coating conductive layer and barrier layer of solar cells, which can improve photoelectric conversion efficiency of batteries, block external impurity corrosion and prolong the service life of photovoltaic modules.

Aerospace & Industrial Wear

Tungsten-based film has extreme high temperature resistance, wear resistance and corrosion resistance, which can be used for protective coating of aerospace high temperature parts to resist high temperature oxidation, airflow erosion and medium corrosion.

At the same time tungsten carbide target can be prepared tool, die wear coating, greatly improve the service life of industrial accessories.  High density tungsten material can also be used as X-ray tube target, suitable for high-end precision equipment use scene.

Tungsten sputtering target compared with other materials

How to choose the right tungsten sputtering target?

• Purity: 3N5 purity is selected for scientific research experiment and common industrial coating, with the best cost performance; 4N purity is selected for medium and high-end display and photovoltaic; 5N ultra-pure target material must be selected for semiconductor and precision microelectronics.  Cost can be precisely controlled by selecting the model according to the needs.
• Size and structure:small cavity and laboratory equipment are suitable for various standard size plane targets; large continuous mass production line gives priority to rotating targets.  Strictly control the size, thickness and installation structure of the target seat of the equipment to ensure the equipment adaptation.
• Power:For low-power and intermittent working equipment, solderless integral target material is selected, so the cost is lower; for high-power and 24-hour continuous mass production equipment, copper-aluminum back plate welding target material must be selected to strengthen heat dissipation and prevent cracking.
• Applications:Pure tungsten is selected for high conductivity and high stability basic film; tungsten titanium alloy is selected for enhanced diffusion barrier performance; tungsten compound target is selected for special functions of optics, wear resistance and lubrication.

Service life extension and maintenance of tungsten target

In daily production, it is necessary to calibrate the magnetic field of the equipment regularly, optimize the sputtering uniformity by relying on the rotating structure of the substrate, widen the target corrosion runway, avoid local excessive wear, and complete the low-power pre-sputtering impurity removal operation before the new target is put into production.

In addition, it is necessary to standardize the equipment operation and maintenance and target storage mode, regularly clean up the cavity deposits, adopt stepped startup and shutdown to avoid cold and hot shock, store the idle target in a dry and constant temperature environment in vacuum seal, customize the target structure and upgrade the equipment configuration in combination with the working conditions of the production line if possible, so as to realize the efficient utilization and long-term stable use of tungsten target in an all-round way.

FAQ

Summarize the problems of users with high search volume in the whole network, accurately answer the all-dimensional questions of model selection, process, maintenance, customization and after-sales service, and solve the core confusion of users.

Q1: What purity of tungsten sputtering target is suitable for semiconductor manufacturing?

Semiconductor chip and high-end microelectronic manufacturing must select 5N (99.999%) ultra-high purity tungsten target or tungsten-titanium alloy target. The extremely low impurity content can avoid film defects, device leakage and performance failure, meeting the strict mass production standards of semiconductors.  Ordinary display, photovoltaic scene 4N purity can meet the demand.

Q2: What is the difference between the welded backing plate target and the integral solderless target?

The integral target has no back plate, simple structure and low price, and is suitable for low-power intermittent experiment and small-batch production.  the weld back plate target material has excellent heat dissipation performance, high temperature cracking resistance and strong stability, is suitable for high-power and 24-hour continuous industrial mas production, and has longer service life.

Q3: What is the normal service life of tungsten sputtering target?

The service life is greatly influenced by power, size, process and equipment.  unde standard working condition, that service life of the planar tungsten target material can reach more than 1000 hours, and can be greatly prolonged after the proces is optimized.  the utilization rate of that rotary target material is high, the service life of the rotary target material is 2 - 3 times of that of the planar target material, and the rotary target material is suitable for long-term continuous production.

Q4: Does the tungsten sputtering target support customization?

Support all-dimensional customization, including special size, special-shaped structure, grooving chamfer, special surface roughness, customized alloy ratio, special back plate material and welding process, which can adapt to various non-standard equipment and special coating process.

Q5: What are the commonly used backing materials for tungsten target?

Mainstream backplane material for copper, aluminum alloy.  The copper back plate has the best heat dissipation performance and is suitable for high-end high-power mass production equipment; the aluminum back plate has higher cost performance and is suitable for conventional low-power and medium-power processes, and can be flexibly selected according to requirements.

Q6: How to store tungsten sputtering target correctly?

The idle target material shall be packed in a vacuum seal to isolate air and water vapor.  Storage environment should be dry, constant temperature, low humidity, avoid oxidation blackening, be affected with damp be affected with damp deterioration.  meanwhile, that stac collision is avoided, and the target material is prevent from deforming and scratching the surface to influence the use effect.

Q7: What is the cause of cracking of tungsten target during sputtering?

The core reasons include: insufficient target density, uneven grain structure, excessive instantaneous cold and hot shock, poor heat dissipation of cooling system, power overload and back plate welding delamination.  The cracking problem can be effectively avoided by selecting high-quality target, optimizing process parameters and standardizing the startup and shutdown process.

Q8: How to effectively improve the utilization rate of tungsten target?

 the method comprise that following step of: preferentially selecting a rotary target material, optimizing magnetic field distribution, balancing substrate movement, standardize process parameters and avoiding partial corrosion.  At the same time, the utilization rate can be improved from 30% to more than 50% by doing well in target pre-sputtering and daily maintenance.

Q9: What certifications do regular tungsten target suppliers need to provide?

Qualified suppliers shall provide GDMS impurity test report, ICP composition analysis report, metallographic structure report, ultrasonic flaw detection report and size accuracy test report, which can realize full traceability of materials and meet the requirements of industrial and semiconductor quality inspection.

Q10: Can the waste tungsten sputtering target be recycled?

It can be recycled.  Tungsten is a rare and precious metal. The worn and worn target material can be purified and regenerated through professional process and reprocessed into qualified sputtering target material, which greatly reduces the procurement cost of enterprises, is green and environmentally friendly, and has high cost performance.

Conclusion and Customization Services

COMBAT can provide full purity grade, full size, all kinds of tungsten sputtering target, covering pure tungsten, tungsten alloy, tungsten compound products, support standard spot and custom tungsten sputtering target, now contact us!