Thin films processing techniques

Many thin-film processing techniques have been developed and further improved in the search for the most suitable approach for a specific application. Typically thin films can be prepared from either the hquid or gaseous phase. Vapour-phase deposition processes, which are more popular, fall into the two main categories of physical and chemical vapour deposition. Atomic layer deposition holds a special position among the chemical vapour deposition techniques because it offers the possibility to produce thin films in a controlled, self-hmiting manner. 

It should be noted that a Z2 dependence of the cross section makes the process very sensitive for heavier elements but proportionately less so for lighter elements. This effect can be observed in Figure 1 when it is noted that the Au peak indicates the presence of only about 0.04j Au compared to about 5056 for the 0 peak. In the latter case the sensitivity is further degraded by the superposition of the 0 peak from the thin film with the distribution from the thick underlying Si substrate. It should be further noted here that the Si substrate is prevented from interfering with other elements by the special preparation of the substrate by placing a film of C on its surface before deposition of the sample thin film. This technique is useful when one has the opportunity to choose the substrate. 

Research on nano- and micro-fabrications based on anodizing treatments combined with chemical/mechanical processes such as laser irradiation, atomic force micro-probe processing and thin film deposition techniques... 

There have been several other thin film synthesis techniques, such as the use of pulsed laser deposition. " However, the promising processing techniques for the economic mass production of mesoporous silica thin films are all based on EISA. Synthesis times can be as short as a few minutes and the processing equipment is readily available. Thus the remainder of this entry focuses on EISA techniques. 

Another approach in the etching of thin-film processes is the lift-off technique. In this approach, photoresist material is first deposited onto the substrate. A mask of inverse pattern is sized and the photoresist material is left on the substrate surface covering the area where metallization does not take place. Metal is then deposited over the substrate surface. The next step removes the photoresist chemically. Figure 16.5 shows the sequence of a typical lift-off... 

Atomic layer deposition (ALD, also known e.g. as ALE) is a material depositing technique originally developed for the processing of thin films. The technique is based on alternating selfisaturating gas-solid reactions in which vaporized active metal precursor is brought into contact with the support [1]. 

Like any other thin-film deposition techniques, sol-gel processing is essentially a mass transport process. The transformation of a liquid solution to a solid crystalline film is accomplished through three steps ... 

In addition to a lattice-matched substrate, sol-gel epitaxy also requires excellent stoichiometry control of the solution. Most of the demonstrated sol-gel epitaxies were performed at relatively low temperatures. Therefore, molecular-level homogeneity is essential. To appreciate fully the delicate features of sol-gel epitaxy, it is now appropriate to compare sol-gel processing with other thin-film deposition techniques. 

In the attempt to achieve optical signal processing, modulation, amplification, and memory functions in integrated circuits similar to those on electrical signals by semiconductor devices, integration of ferroelectric devices is the ultimate goal. However, to achieve integration of microscopic devices based on materials as complex as oxide ferroelectrics, which are predominantly multi-component metal oxide compounds, reliable thin-film deposition techniques are critically needed. One of the most important aspects of multicomponent oxide thin-film deposition is the control of stoichiometry. 

Sputtering Thin film deposition technique based on the momentum transfer between accelerated ions and a target of source material. The process is undertaken at reduced pressure. 

Infrared spectroscopy is another technique employed to study the adsorption from solution of different species. White et al. [119] studied the adsorption of methoxy-methylsilanes with sihca catalyzed by amines using a thin film IR technique which has been described elsewhere [68]. The results obtained by White et al. [119] are in agreement with an independent work reported by Ahmad et al. [20] who studied the adsorption of acetophenones on silica. In both cases hydrogen-bond interaction is one of the most important factors in the adsorption process. In both studies [119,120] the structure of the adsorbed species are described based on IR absorption bands. 

Thin-film deposition technique in which a material is formed from a beam of sublimated atoms. The MBE process is valued for its precise control of atomic species on the growth surface, both for desired and undesired species. 

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