Deposition method

A wide variety of deposition methods are available, and several systems of each type are produced commercially. A review of typical systems has been published [10]. In regard to the CVD of insulating films, four general reactors are presently used atmospheric pressure CVD (APCVD), low and medium temperature low pressure CVD (LPCVD), and plasma-enhanced CVD (PECVD). 

APCVD systems allow for high throughput and even continuous operation, while LPCVD provides for superior conformal step coverage and better film homogeneity. PECVD has been traditionally used where low temperatures are required, however, film quality is often poor, e.g., silicon nitride grown by PECVD contains significant 

Step coverage poor poor conformal poor 

Film properties good good excellent poor 

Uses passivation, insulation passivation, insulation insulation passivation, insulation 

A great variety of deposition methods has been successfully used up to now to deposit cBN-containing thin films, among them both physical (PVD) and chemical vapor deposition (CVD) techniques. All these methods have in common that the growing film is exposed to an intense ion bombardment which plays a crucial role in cBN thin film formation. Among the PVD methods initially such techniques 

5 Vapor Phase Deposition of Cubic Boron Nitride Films 

In their successful attempts to grow cBN thin films, most authors have applied moderately increased substrate temperatures, T, mostly in the range between 200 and 500°C. However, the growth of cBN thin film is also possible at temperatures as high as 1000°C [35]. The low temperature limit for cBN film deposition is at about 150°C, as has been foimd by Mirkarimi [36] for ion-assisted pulsed laser deposition and more reeently by Hofsass et al. [34] for MSIB deposition. 

The dimension and synthetic method of particulate catalysts on semiconductors have an impact on their performance. In this section, we will discuss several techniques used to fabricate particles and films of Pt and RUO2, two materials widely used for PEC electrode catalysis. 

Several experiments have demonstrated platinum catalyst particle deposition over p-type materials using cathodic processes [30-32]. A typical deposition can be performed using an electrolyte made of 0.01 M chloroplatinic acid (H2PtCl6) in 

2 M hydrochloric acid (HCl) under galvanic square wave conditions with a duty cycle of 0.25 s at — 1 mA/cm followed by 2 s at open circuit, this cycle is repeated until a total charge of 10 mC/cm is reached. The addition of illumination may be necessary for p-type photocathodes in order to provide sufficient minority carrier electrons to drive cathodic electrodeposition. When a n-type semiconductor is used as a PEC electrode, typical cathodic electrodeposition (3-9 mA/cm ) of RuOa xHaO can be obtained from a 0.04 M aqueous acidic ruthenium chloride (RuCl3 xH20) solution [33]. Anodic deposition of this material is also feasible by adding 0.1 M NaAcO [34]. 

PVD processes are usually employed to deposit continuous films with thicknesses ranging from 100 nm to a few microns. However, it is possible to form islands of 

This method consists of the thermal decomposition of RUO4 to RUO2 on the surface of the photoanode. Calcination of the substrate at 300 °C for 30 min is suggested to obtain better contact with the RUO2 nanoparticles, but it is not essential. This method is time consuming and requires a fume hood as well as acetone (or isopropanol) and dry ice to decrease the temperature of the RUO4 mixed in pentane [38]. 

---

Metallization layers are generally deposited either by CVD or by physical vapor deposition methods such as evaporation (qv) or sputtering. In recent years sputter deposition has become the predominant technique for aluminum metallization. Energetic ions are used to bombard a target such as soHd aluminum to release atoms that subsequentiy condense on the desired substrate surface. The quaUty of the deposited layers depends on the cleanliness and efficiency of the vacuum systems used in the process. The mass deposited per unit area can be calculated using the cosine law of deposition ... 

Reduction. Reduction of haUdes usiag hydrogen—hydrocarbon mixtures is sometimes done ia the presence of a graphite carrier or usiag metals possessing high melting points, ie, the van Arkel gas deposition method (4). If a plasma gun is employed, finely powdered (< 1 //m) carbides are obtained... 

The red pigment has been proposed to be usable ia both the pigment dispersioa method and the electro deposition method (171,172). The blue dye may be used ia the dyeiag method fabricatioa process (173). 

An MWCNT has inner concentric tube(s) with smaller diameter(s) inside its hollow, and it is normally prepared in the carbon electrode of the arc-discharging method or by chemical vapour deposition method (see Chaps. 2 and 12). Influence of such inner tubes on the most outer layer in MWCNT is of interest with respect to electronic similarity of MWCNT and SWCNT. 

Ozin and Huber 112) synthesized and characterized very small silver particles, Ag n = 2-5) by conventional deposition methods, as well as by a novel technique that they have termed "cryophotoaggrega-tion. This study will be discussed in detail in Section III. Of interest here is a study of silver atoms and small, silver clusters entrapped in ice and high-molecular-weight paraffin (n-C22H46, n-C32Hg8) matrices 146) (see Figs. 7 and 8, and Tables IV and V). Besides the intriguing, multiple-site (solvation) occupancy of atomic silver in ice matrices, and their thermal and photochemical interconvertibility, their extremely... 

Fig. 11—Schematics of various deposition methods of multilayer films.

Coating Maximum Hardness (GPa) Optimum Si Content (at.%) Deposition Method Authors Reference... 

The vapor deposition method at variable substrate temperature provides additional insight into the structure and wetting properties of 8CB in its various phases. If the substrate temperature is between 41 and 33°C, fiat islands 32 A thick are formed if only a small amount of 8CB is condensed on the surface. The size of these fiat islands increases with deposition time while their height remains constant until a uniform layer is formed. If more 8CB is deposited, droplets form on top of the film. This is shown in the image of Figure 14. 

VOx supported on TiOi showed good catalytic activity in the selective oxidation of H2S to ammonium thiosulfate and elemental sulfur. V0x/Ti02 catalysts prepared by the precipitation-deposition method can achieve higher vanadium dispersions, and higher H2S conversions compared to those prepared by the impregnation method. 

A number of other deposition methods have been used for growing diamond, with varying degrees of success. These include oxyacetylene welding torches, arc jets and plasma torches, laser ablation and hquid phase crystallisation, but none of these yet reahstically compete with the hot filament or microwave systems for reliability and reproducibility. 

Generally, the experimental results on electrodeposition of CdS in acidic solutions of thiosulfate have implied that CdS growth does not involve underpotential deposition of the less noble element (Cd), as would be required by the theoretical treatments of compound semiconductor electrodeposition. Hence, a fundamental difference exists between CdS and the other two cadmium chalcogenides, CdSe and CdTe, for which the UPD model has been fairly successful. Besides, in the present case, colloidal sulfur is generated in the bulk of solution, giving rise to homogeneous precipitation of CdS in the vessel, so that it is quite difficult to obtain a film with an ordered structure. The same is true for the common chemical bath CdS deposition methods. 

V-Sb-oxide samples with Sb V ratios of 1.0 and 3.0 were prepared by the following precipitation-deposition method VCI3 is dissolved in a O.IN aqueous HCl solution (A) and SbCls is dissolved in a 3-5N HCl aqueous solution (B). The dropwise addition of A to B leads to the formation of a white precipitate (mainly Sb-hydroxide) and a dark blue solution due to VO ions. VO is then precipitated over the Sb-hydroxide by adding dropwise a concentred aqueous solution of... 

First, the selective deposition method was developed. It is the novel preparation technique, where the maximum loading around 20 wt% with keeping the particle size below 2nm [14]. Figure 6 shows Pt metal particles supported on monodispersed spindle titania particles. 

---