Cold atmospheric plasma spraying is used to produce thin coatings of copper and tin between 20-80 μm thickness for use in diffusion soldering. This study presents an alternative process to apply composite solders directly onto power electronic bare dies. The formation of intermetallic phases may be promoted by the homogeneous distribution of the Cu and Sn particles as they are presented not in a layered structure but as a pseudo alloy within the coating. The Cu and Sn powder is mixed in situ using two powder conveyors, enabling adjustable mix ratios. The presented approach has been shown to produce a homogeneous particle distribution within the coating. Furthermore, preliminary experiments indicate the feasibility of the technology for applications in diffusion soldering.

A thermoelectric power generating device, in which all components were fabricated by plasma spray technique, was manufactured and its performance was evaluated. Its basic unit was composed of (Ca,Bi) 3 Co 4 O 9 p-type semiconductor chip and (Sr,Y)TiO 3-x n-type semiconductor chip. The plasma sprayed (Ca,Bi) 3 Co 4 O 9 and (Sr,Y)TiO 3-x deposits showed the Seebeck effect according to expectation. However, the ZT values, which indicated the thermoelectric performance, were still poor because of the low electric conductivity. Measurements of some basic properties revealed that increase of the target phase content was important for the p-type material. On the other hand, decrease of the resistivity was strongly desired for the n-type material by process improvement. Power generating test was performed using pipe shape device fully fabricated by plasma spraying and the electric output was successfully obtained under a temperature gradient.

Thermoelectric (TE) power generation from waste heat is recently attracted much attention as one of energy-saving technologies. In this paper, Co-doped n-type iron silicide semiconductor was plasma sprayed under various spray conditions to find the optimum spray-forming conditions. Then Co-doped iron silicide TE device with thickness ranging from 3 to 5 mm and the area of over 100 cm square was produced in the form of a plate or on tube. The paper examines the microstructure and evaluates thermal and electric properties. Paper includes a German-language abstract.

Yttrium oxide (Y 2 O 3 ) coatings have been prepared with high power axial injection plasma spraying using fine powder slurries. It is clarified that the coatings have high hardness, low porosity and high erosion resistance against CF4 contained plasma in the previous study. This suggests that the plasma spraying of Y 2 O 3 with slurry injection techniques is applicable to fabricating equipments for semiconductor devices, such as dry etching. Surface morphologies of the slurry coatings with splats are almost similar to conventional plasma-sprayed Y 2 O 3 coatings, identified from microstructural analysis by field emission SEM in this study. However, no lamellar structure has been seen from cross sectional analysis, which is apparently different from the conventional coatings. It has also been found that crystal structure of the slurry Y 2 O 3 coatings mainly composed of metastable phase of monoclinic structure, whereas the powders and the conventional plasma spray coatings have stable phase of cubic structure. Mechanism of coating formation by plasma spraying with fine powder slurries will be discussed based on the findings.

High purity oxide ceramic powders of alumina (Al 2 O 3 ) and yttria (Y 2 O 3 ) for plasma spraying have been developed to apply to semiconductor and flat-panel-display (FPD) production equipments. The ceramic coatings onto inside chamber wall of the equipments are required to have highly erosion resistance against CF containing plasma, widely used in dry etching process for micro-fabrications of the devices. Yttria is increasingly used in this application due to the high resistance compared to alumina. It is found that the yttria coating formed from agglomerated-and- sintered powder consisting of large primary particle has smoother eroded surface. Considering that particle deposition onto the devices, this coating will be effective to decrease generation of large sized particle, which is easily deposit onto the devices. Electric insulating properties of the coatings are also investigated to apply to electrostatic chuck. Electric breakdown voltage of yttria coatings is almost comparable to that of alumina coatings. However, yttria is difficult to apply due to its lower mechanical strength. Using smaller powder as feedstock is effective to improve the electric properties and influence of coating purity is lower than the powder size.

This study investigates the influence of plasma spray conditions on the structural, mechanical, and plasma-erosion properties of yttrium oxide coatings. Powder feed rate, plasma power, and primary particle size appear to have little effect on plasma erosion properties, hardness, surface morphology, and coating structure. However, a Y 2 O 3 coating produced with fine powder retained a smooth erosion surface despite its porosity and relatively low hardness.

In this study, high-power axial-injection suspension plasma spraying is used to synthesize yttrium oxide coatings from fine powder slurries. The coatings are assessed based on microstructure, hardness, and porosity and compared with coatings produced by other spraying methods. Resistance to erosion from CF 4 containing plasma is also investigated. Test results show that the suspension plasma sprayed Y 2 O 3 coatings are superior in terms of density, hardness, uniformity, and plasma erosion resistance. They also retain a smoother surface when exposed to plasma that contains CF 4 .

Erosion properties of high purity alumina (Al 2 O 3 ) and yttria (Y 2 O 3 ) coatings prepared by plasma spraying have been investigated against process plasma in semiconductor and liquid-crystal-display (LCD) production equipments for dry etching. Studies on plasma power dependency have revealed that yttria coatings have showed higher anti-plasma erosion resistance than alumina coating as well as sintered alumina bulk at every condition. Although yttria coatings are inferior to sintered yttria bulk, the difference of the resistance becomes smaller with increasing plasma power. This result positively promotes the application of the yttria spray coating because of increasing plasma power in actual process. Erosion properties of the coatings against Ar/CF 4 /O 2 plasma, whose composition is increasingly being used in commercial process, are also investigated where physical etching effect becomes stronger than the typical CF 4 /O 2 case. It has been found that order of durability (yttria bulk > yttria coatings > alumina bulk > alumina coating) is independent of the gas species used in this study. The mechanism of the plasma erosion is discussed through micro-structural analysis of the eroded surfaces.

Application of plasma sprayed ceramic coatings with a high purity of more than 99.9% has been sharply increasing in semiconductor and liquid-crystal-display (LCD) production equipments for dry etching, sputtering and ashing in the last few years. The size of the equipments becomes larger with increasing Si wafer size and the LCD size that promotes the replacement from conventional techniques, such as alumite film and bulk ceramics, to plasma spray coatings, where the high durability against the plasma erosion (anti-plasma erosion resistance) is required. However, as far as we know, no systematic studies on the plasma-erosion properties are reported. In this work, durability of plasma sprayed ceramic coatings against CF 4 /O 2 plasma are investigated by reactive ion etching (RIE) system and are compared to that of the conventional techniques. The erosion mechanism is also discussed through the micro-structural analysis.

The main advantage of the cold spray process is minimal influence on the substrate properties with sufficiently high bond strength. This advantage allows metal coating to be applied to the specific objects which were never subjected to the thermal spray process. The examples of the low pressure cold spray application to the glass objects, magnet sensors and electronic elements are presented and discussed.

Thermal spray coatings are used for a broad range of purposes in the semiconductor equipment industry. A primary use of thermal spray coatings for thin film applications is to provide surfaces on process chamber components that promote particle reduction and contamination control during chamber operations. Coatings are also used to provide the desired dielectric properties for critical components such as electrostatic chucks (ESC) and heater pedestals; to prove chemical and corrosion-resistance for process kit components and showerheads; as well as serving a wide range of other purposes. This paper reviews future needs for thermal spray coatings in semiconductor equipment and identifies some of today’s coating challenges. Areas discussed include coating design considerations; chemical, corrosion and plasma erosion issues influencing the selection of materials, coatings and processes. Brief discussion will be provided for future anticipated needs in materials, coatings, processing and the manufacture of thermal spray coatings for such applications.

The work presented in this paper addresses some of the challenges of manufacturing thermoelectric (TE) generators by thermal spraying. One of the main obstacles is achieving good coat-on-coat bonding between different types of materials. The coatings must also be mechanically stable and optimized for their respective function. At least four types of materials are required, including electrical insulators, conductors, and thermoelectrically active p- and n-type semiconductors. Four ceramic and three metal feedstock powers were deposited by APS, HVOF, and HVAF spraying using special masking systems, substrate pretreatments, and layer thickness monitoring. After process optimization for each material, multilayer TE generator modules were successfully produced.

This paper provides a summary of the status and potential of thermal spray activities in Korea. It describes how various market sectors in Korea are using spray coating technology and presents annual sales estimates and share of market data broken out by industry, spraying technology, and patents awarded. It also reviews recent advancements in the development and use of thermal spray technology in Korea along with anticipated future impacts.

Sintering ceramics have been widely used in industries which require electrical and mechanical properties. Thermal sprayed ceramics coatings are also applied for the industries, however the coating which has micron size pores are limited their applications due to inferior electrical and mechanical properties compared with sintering bulk. To expand thermal sprayed ceramics coating applications, dense coatings prepared by suspension plasma spraying are widely studied. Dense Al 2 O 3 coatings are applicable to fabricating equipment for electronics devices, such as ESC. There are no reports regarding electric properties of plasma sprayed dense Al 2 O 3 coating with different spray conditions. In this study to achieve a electric properties of dense Al 2 O 3 coating, spray parameters such as plasma power, gas flow rate and spray distance are investigated. Suspension materials prepared with three microns Al 2 O 3 powder are sprayed by high power suspension plasma spraying system. Spray conditions, plasma power, gas flow rate, and stand-off distance affect the coating density, crystal phase, and mechanical and electrical properties. Mechanism of coating formation by plasma spraying with fine powder suspensions will be discussed based on the findings. Al 2 O 3 coatings obtained by the plasma spraying is applied for application to application utilizing the electrical insulation properties of such electronics devise manufacturing equipment components is proceeding.

This study investigates plasma erosion mechanisms in alumina and yttria coatings produced by air plasma spraying. Plasma exposure tests were conducted in ICP etchers using CF 4 , Ar, and O 2 as process gases. Etching rates were calculated based on height differences between masked and unmasked areas and coating cross-sections, surface morphologies, and phase distributions were analyzed. In the Al 2 O 3 layers, erosion increased with increasing CF 4 concentration and fluoridation of the coating surface was confirmed, suggesting that chemical erosion is the dominant mechanism. Although fluoridation occurred on Y 2 O 3 surfaces as well, the amount of erosion in CF 4 was the same as in the Ar environment. It is thus assumed that the fluoride formed on Y 2 O 3 surfaces is very stable and that physical erosion due to ion sputtering is the dominant mechanism.

SrTiO x is an expected oxide thermoelectric material, which performance can be improved by doping Y 3+ in place of Sr 2+ . However, the maximum content of Y 3+ is limited to about 10% because of the phase transformation in the equilibrium sintered material. By contrast, plasma sprayed (Sr, Y)TiO x , which was essentially rapidly quenched, could solve Y up to 20% of Sr-site without the second phase, and produce the increase in the electric conductivity and the decrease in the thermal conductivity. But the absolute value of Seebeck coefficient decreased with an increase of Y content. As the result, the ZT value, which showed the performance for thermoelectric power generation, was reached only 0.1 in the Y content range 10% to 25% of Sr site.

In the semiconductor industry, plasma etching processes are widely used. Process chamber parts that are located in the plasma etching system are also exposed to the harsh environmental conditions. Thus, parts located close to the process area are typically coated with yttria to increase service life, and thus process performance. However, such yttria coatings are usually porous, and thus can be attacked by fluorine containing plasma. In order to increase the lifetime of the components in the plasma etching system, this research project aimed to improve the protective yttria layer by reducing the porosity of the protective layer. Specifically, a design of experiment was employed in which the porosity was the target value. The main effects of the coating parameters and their interactions including the surface treatment before the coating process were determined. Furthermore, the bonding of the protective coating to the component to be protected, as well as the element distribution and the coating morphology were investigated. The results and their ramifications with respect to the envisaged application will be discussed.

Titanium dioxide (TiO 2 ) has emerged as an excellent photocatalyst material for environmental purification about two decades ago. In order to avoid the use of TiO 2 powder, which requires later separation from the treated liquid, few researchers reported on ways of fixing TiO 2 . In these cases, many difficulties must be overcome such as maintaining the photoactive anatase phase as well as the mechanical stability and avoiding the mass transfer limitations. Thermal spraying seems to be an appropriate process to provide ceramic coatings exhibiting such characteristics. The present work assesses the influence of several spray parameters on the morphology of deposits, dominated by two void systems – interlamellar pores and interlamellar cracks – and on their crystalline structures. TiO 2 was atmospherically plasma sprayed by systematically varying the process conditions including torch power, plasma gas mixture Ar/H 2 and Ar/He, and cooling device. An analytical procedure based on XRD patterns was established for the determination of the relative amounts of anatase and rutile in the coatings. An Ar/He mixture as compared to an Ar/H 2 one seems to enhance the formation of anatase from 38vol% to 44vol%. In both cases, a reduction of the plasma power increases the amount of anatase. Several methods of porosity determination were performed: image analysis, Archimedean porosimetry and calculation from phases, mass and thickness. Generally, the results indicate a total porosity varying between 15 and 25% depending on the spraying conditions.

According to a recent survey, the thermal spray market in Japan is approximately 100 billion yen. The market consists of three sectors, coating services (45 billion yen), in-house production (45 billion yen), and sales of thermal spray equipment and consumables (10 billion yen). This paper provides an overview of the coating services market broken out by application segments. It also discusses future trends.

In this work, alumina coatings are produced by atmospheric plasma spraying using dry-ice blasting to prepare substrate surfaces. Feedstock powder and coating microstructure are examined and dielectric strength and ac-dc breakdown voltages are measured. The results show that dry-ice blasting improves the dielectric properties of alumina coatings produced by atmospheric plasma spraying.