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Thin Film Coating: Characterizing the Evolving Properties of Aluminium Thin Films Prepared via RF Magnetron Sputtering /

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Thin Film Coating: Characterizing the Evolving Properties of Aluminium Thin Films Prepared via RF Magnetron Sputtering // Fredrick Madaraka Mwema.
作者:	Mwema, Fredrick Madaraka,
面頁冊數:	1 electronic resource (341 pages)
附註:	Source: Masters Abstracts International, Volume: 82-11.
Contained By:	Masters Abstracts International82-11.
標題:	Materials research. -
電子資源:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28283791
ISBN:	9798708788832

Thin Film Coating: Characterizing the Evolving Properties of Aluminium Thin Films Prepared via RF Magnetron Sputtering /
Mwema, Fredrick Madaraka,

Thin Film Coating: Characterizing the Evolving Properties of Aluminium Thin Films Prepared via RF Magnetron Sputtering /Fredrick Madaraka Mwema. - 1 electronic resource (341 pages)

Source: Masters Abstracts International, Volume: 82-11.

The purpose of this research was to prepare, investigate and understand the characteristic behaviour of aluminium thin film coatings deposited on various substrates through radio-frequency (RF) magnetron sputtering under different RF powers and substrate temperatures. Aluminium and aluminium alloy thin films are widely used in micro-electronics, optics, solar devices and surface protectors of different substrates. Their applications in these fields are motivated by their low resistivity, high reflectance, sacrificial nature in various media, low-cost and the availability of the bulk aluminium metal. However, the application of aluminium thin films is limited by microstructural defects, such as the formation of oxides (during and post-deposition), porosity and hillocks.An extensive review of the existing literature revealed that porosity and hillocks, which are mostly formed during the deposition of the films, can be reduced by using RF magnetron sputtering at a low temperature range (below 100°C). It was also deduced that substrate type and RF power influence the quality of the Al thin films obtained via the magnetron sputtering. Radio-frequency (RF) magnetron sputtering is a physical vapour-deposition technique, which has been shown to prepare quality thin films. Compared with most other existing techniques, it is possible to deposit these films at low temperatures, and by controlling various processing parameters.As such, the Al thin films were deposited on steel, titanium and glass substrates at temperatures ranging between room temperature (RT), 100°C, RF powers between 150 W, and 350 W. The obtained Al thin films were then characterised through scanning electron microscopy (SEM), field-emission scanning electron microscopy (FESEM), low-angle X-ray diffraction (XRD), atomic-force microscopy (AFM), non-contact optical-surface profiling (OSP), nanoindentation, micro-scratch and micro-wear techniques, in order to understand the microstructural topography and the mechanical characteristics of the films. Additionally, mathematical methods (with the emphasis on fractal techniques) were used to study the microstructural and topographical inter-relationships between the processing parameters.It was observed that an increase in substrate temperature (Ts) at constant RF power enhanced the formation and the growth of the aluminum structures. Whereas, the films deposited at room temperature on commercially pure titanium (Cp-Ti), Ti6Al4V, mild steel and stainless steel exhibited low crystallinity, at temperatures beyond 60°C, the aluminium structures formed well-defined grains and crystalline structures. It was very difficult to detect aluminium structures when the deposition was undertaken at room temperature on glass substrates. At temperatures between 50°C and 65 °C, less crystalline and amorphous aluminium structures were observed while crystalline structures were present between 65 °C and 95°C. An increase in substrate temperature between room temperature and 100°C for Al films deposited on mild steel revealed the formation and occurrence of fine and highly inter-connected aluminium structures at a higher temperature. However, under similar conditions, fine, inter-connected and layered aluminium structures were observed at 100°C for films deposited on stainless steel substrates.The fractal dimension was seen to decrease with the increase in temperature for mild steel substrates and it increased with the substrate temperature for stainless steel substrates. The differences could be attributed to the observed layering and the lateral development of the films on stainless steel substrates. When deposited on glass substrates at a temperature varying between 55°C and 95°C, the films were seen to grow vertically rather than laterally, due to lower variance in the fractal dimension and increasing average and root mean square roughness values. Generally, the surface roughness was seen to increase with the substrate temperatures, thereby indicating the growth of surface features with the increase in substrate temperature. The porosity, size and the density of the hillocks and oxides decreased with an increase in the temperature of the substrate.It was observed that the increase in RF sputtering power influences the microstructure, the mechanical and the topographical characteristics of aluminium thin films. There was no proportional relationship between the surface roughness and the increase in the RF powers of aluminium thin films deposited on stainless-steel and mild steel substrates, which was deposited at RF powers increasing between 150 W and 350 W at a constant substrate temperature of 90°C. Aluminium thin films deposited on mild steel, stainless-steel, commercially pure titanium (Cp-Ti) and Ti6Al4V substrates at room temperature, however, revealed an increase in surface roughness, with the RF power between 150 W and 200 W. It was observed that films deposited between 200 W and 300 W exhibited surface pits and valleys, when compared with those deposited at 300-350 W. Additionally, the fractal dimension decreased insignificantly between 150 W and 350 W for those films deposited on the metallic substrates. This observation indicates that, unlike substrate temperature, RF power does not considerably influence the lateral roughness of the films. The crystallinity, the evolution of defects and the growth of surface features were influenced greatly by the variations in RF power.The study concluded that sputtering aluminium thin films within the RF power range of 300-350 W and at a substrate temperature ranging between 70°C and 95°C produces structures with fewer defects and better mechanical integrity for improved performance in various applications. Future work is recommended involving systematic multi-layer sputtering at a higher temperature within this RF power range, in order to reduce the effect of oxidation on the properties and the performance of aluminum thin films.

English

ISBN: 9798708788832Subjects--Topical Terms:

3686999
Materials research.
Subjects--Index Terms:

Glass substrates

Thin Film Coating: Characterizing the Evolving Properties of Aluminium Thin Films Prepared via RF Magnetron Sputtering /
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However, the application of aluminium thin films is limited by microstructural defects, such as the formation of oxides (during and post-deposition), porosity and hillocks.An extensive review of the existing literature revealed that porosity and hillocks, which are mostly formed during the deposition of the films, can be reduced by using RF magnetron sputtering at a low temperature range (below 100°C). It was also deduced that substrate type and RF power influence the quality of the Al thin films obtained via the magnetron sputtering. Radio-frequency (RF) magnetron sputtering is a physical vapour-deposition technique, which has been shown to prepare quality thin films. Compared with most other existing techniques, it is possible to deposit these films at low temperatures, and by controlling various processing parameters.As such, the Al thin films were deposited on steel, titanium and glass substrates at temperatures ranging between room temperature (RT), 100°C, RF powers between 150 W, and 350 W. The obtained Al thin films were then characterised through scanning electron microscopy (SEM), field-emission scanning electron microscopy (FESEM), low-angle X-ray diffraction (XRD), atomic-force microscopy (AFM), non-contact optical-surface profiling (OSP), nanoindentation, micro-scratch and micro-wear techniques, in order to understand the microstructural topography and the mechanical characteristics of the films. Additionally, mathematical methods (with the emphasis on fractal techniques) were used to study the microstructural and topographical inter-relationships between the processing parameters.It was observed that an increase in substrate temperature (Ts) at constant RF power enhanced the formation and the growth of the aluminum structures. Whereas, the films deposited at room temperature on commercially pure titanium (Cp-Ti), Ti6Al4V, mild steel and stainless steel exhibited low crystallinity, at temperatures beyond 60°C, the aluminium structures formed well-defined grains and crystalline structures. It was very difficult to detect aluminium structures when the deposition was undertaken at room temperature on glass substrates. At temperatures between 50°C and 65 °C, less crystalline and amorphous aluminium structures were observed while crystalline structures were present between 65 °C and 95°C. An increase in substrate temperature between room temperature and 100°C for Al films deposited on mild steel revealed the formation and occurrence of fine and highly inter-connected aluminium structures at a higher temperature. However, under similar conditions, fine, inter-connected and layered aluminium structures were observed at 100°C for films deposited on stainless steel substrates.The fractal dimension was seen to decrease with the increase in temperature for mild steel substrates and it increased with the substrate temperature for stainless steel substrates. The differences could be attributed to the observed layering and the lateral development of the films on stainless steel substrates. When deposited on glass substrates at a temperature varying between 55°C and 95°C, the films were seen to grow vertically rather than laterally, due to lower variance in the fractal dimension and increasing average and root mean square roughness values. Generally, the surface roughness was seen to increase with the substrate temperatures, thereby indicating the growth of surface features with the increase in substrate temperature. The porosity, size and the density of the hillocks and oxides decreased with an increase in the temperature of the substrate.It was observed that the increase in RF sputtering power influences the microstructure, the mechanical and the topographical characteristics of aluminium thin films. There was no proportional relationship between the surface roughness and the increase in the RF powers of aluminium thin films deposited on stainless-steel and mild steel substrates, which was deposited at RF powers increasing between 150 W and 350 W at a constant substrate temperature of 90°C. Aluminium thin films deposited on mild steel, stainless-steel, commercially pure titanium (Cp-Ti) and Ti6Al4V substrates at room temperature, however, revealed an increase in surface roughness, with the RF power between 150 W and 200 W. It was observed that films deposited between 200 W and 300 W exhibited surface pits and valleys, when compared with those deposited at 300-350 W. Additionally, the fractal dimension decreased insignificantly between 150 W and 350 W for those films deposited on the metallic substrates. This observation indicates that, unlike substrate temperature, RF power does not considerably influence the lateral roughness of the films. The crystallinity, the evolution of defects and the growth of surface features were influenced greatly by the variations in RF power.The study concluded that sputtering aluminium thin films within the RF power range of 300-350 W and at a substrate temperature ranging between 70°C and 95°C produces structures with fewer defects and better mechanical integrity for improved performance in various applications. Future work is recommended involving systematic multi-layer sputtering at a higher temperature within this RF power range, in order to reduce the effect of oxidation on the properties and the performance of aluminum thin films.
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