An Overview of Tantalum Sputtering Target Material

An Overview of Tantalum Sputtering Target Material

Tantalum sputtering target material is a chip of tantalum obtained by pressure processing. It has high chemical purity, small grain size, as well as good recrystallized structure and consistency of three axes. Tantalum sputtering target is mainly used in optical fiber, the semiconductor chip and integrated circuit sputtering deposition film, as well as in cathode sputtering coating, high vacuum suction active material, etc., which is an important material for thin film technology.

Classification of the tantalum target

According to the application field, it can be divided into optical tantalum target and semiconductor tantalum target.

Tantalum-Sputtering-Target
Tantalum-Sputtering-Target

The performance index of the tantalum target

  • Purity

Metal impurities do not affect the sputtering process but affect the life of tantalum film, and the purity of the target material is different in different application fields. The impurities U, Th, and other radioactive elements have a negative impact on MOS, while K, Na and other alkali metals have a negative impact on MOS interface performance. In addition, transition metals such as Fe, Ni, Cr and refractory metals such as W, Mo, and Nb generate leakage current at the interface. Therefore, the content of the above impurity elements should be strictly controlled.

  • Porosity

The target material should be dense enough. If there are pores in the target material, the gas in the pores will be released in the sputtering process, and an arc will be generated, causing tiny particles to sputter out of the target and generating uneven points on the film.

  • Grain size

The size of grain affects sputtering uniformity and sputtering speed. Typically, the grain size is required to be less than 100 microns, since the large grain size causes uneven sputtering and irregular nodules on the target. Meanwhile, no crystal band is allowed and the grains should be uniform on the whole target surface.

  • Texture

The texture difference has a great influence on sputtering speed, and (100) texture is usually required.

  • Surface finishingment

If the surface finish of the target material is not high enough, it is easy to form small bumps in the sputtering process.

  • Uniformity

Uniformity should be consistent in all directions of the target and between each target.

Tantalum-target
Tantalum-target

Applications of the tantalum target

In recent years, with the rapid development of semiconductor technology, electronic devices are becoming more and more miniaturized and integrated, and the thin film technology is used in the manufacturing process.

Tantalum target is mainly used for sputtering coating. Tantalum film, tantalum alloy film, silicon tantalum oxide film, tantalum nitride film, and tantalum oxide film have a wide range of applications. Tantalum oxide is used in the resistance and capacitance of integrated circuits and the resistance of hybrid circuits; tantalum film forms a barrier layer to prevent corrosion when spraying printed circuit; tantalum film is also used as seed in magnetic resonance devices. The total global demand in these areas is about 30t annually.

Another major use of tantalum is as a diffusion barrier between silicon and copper conductors in integrated circuits. Compared with other metals, tantalum, as a barrier layer of copper, has a lower diffusion rate, higher interlayer bonding strength, and heat resistance. The global demand for sputtering targets in this application field is expected to increase to 200t.

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Tantalum Processing Materials used in the Electronics Industry

Tantalum Processing Materials used in the Electronics Industry

With the advent of the era of big data, the storage of big data has become a matter of concern. Tantalum materials are developing at an amazing speed in today’s rapid development of the electronics industry.

tantalum target

Tantalum capacitors

Tantalum capacitors are one the indispensable electronic components for radar, aerospace aircraft, and missiles, and are widely used in civil applications, such as mobile communication, electronic equipment, instruments, and other aspects. On the contrary, the development of the electronic industry requires more and more stringent miniaturization and high reliability of tantalum capacitors.

Tantalum capacitors
Tantalum capacitors

Capacitor grade tantalum wire

Capacitor grade tantalum wire is used to make anode lead of tantalum electrolytic capacitor, and its advantages are high permittivity of the oxide film and high reliability. Compared with metallurgical tantalum wire, capacitor grade tantalum wire has high chemical purity, good surface finish, and anti-oxygen brittleness. Using tantalum powder as raw material, capacitor tantalum wire is made by powder metallurgy method after forming tantalum bar, and then through rolling, drawing, and other metal plastic processing. As a result, its surface is smooth and clean, and no grooves, burrs or other defects.

Capacitor grade tantalum wire
Capacitor grade tantalum wire

The important performance indexes of capacitor-grade tantalum wire include tensile strength, linearity, chemical composition, leakage current, etc. The diameter of the capacitor-grade tantalum is generally between Φ0.15 mm to Φ1.0 mm, and the tensile strength is between 400mpa and 1700mpa.

Tantalum target

The purity of the tantalum target is 99.95%, the surface is smooth, the grain diameter is less than 100μm, and the grain texture is mainly [111] type texture. Because of its high conductivity, high thermal stability, and barrier to foreign atoms, tantalum can be used as a barrier layer to prevent copper from diffusing into silicon. As electrode materials and surface engineering materials, tantalum target has been widely used in liquid crystal display (LCD) and heat-resistant, corrosion-resistant, and highly conductive coating industries.

Tantalum target
Tantalum target

Tantalum sputtering target material has become a key raw material in the semiconductor industry, which is irreplaceable and has a broad application prospect. The tantalum sputtering target is completed by physical vapor deposition. The specific process includes high-pressure accelerated gaseous ions bombarding the tantalum target surface, enabling the atoms on the target surface to get enough energy and break free, sputtering on the silicon chip, and finally forming the precise wiring structure in the semiconductor chip with photolithography, corrosion, and other processes. Tantalum material can be used for various thin-film applications, as diffusion barrier material applied to memory devices, such as gate electrodes of MOSFET devices and protective coating on printing head devices.

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