Films grain growth

THIN FILMS GRAIN GROWTH AND DIMENSIONAL STABIUTY... 

At higher temperatures, deposits tend to be columnar (Fig. 2.13 a and b) as a result of uninterrupted grain growth toward the reactant source. The structure is also often dependent on the thickness of the deposit. For instance, grain size will increase as the thickness increases. A columnar-grain structure develops, which becomes more pronounced as the film becomes thicker. 

Conventional electrodeposition from solutions at ambient conditions results typically in the formation of low-grade product with respect to crystallinity, that is, layers with small particle size, largely because it is a low-temperature technique thereby minimizing grain growth. In most cases, the fabricated films are polycrystalline with a grain size typically between 10 and 1,000 nm. The extensive grain boundary networks in such polycrystalline materials may be detrimental to applications for instance, in semiconductor materials they increase resistivity... 

Ultrasonic-assisted rinsing has been tested for the growth of ZnS thin films. The growth rate clearly increased, and the morphology of the films became smoother, whereas the grains became smaller. The band gap of the ZnS films was 3.67 eV.11... 

The (N — 6)-rule was derived for two-dimensional grain growth in a thin film. However, only the interior grains were treated. What is the rule for the growth... 

Poly crystalline silicon (poly-Si) has been formed by the plasma-enhanced decomposition of dichlorosilane in argon at temperatures above 625 °C, a frequency of 450 kHz, and a total pressure of 27 Pa. Doped films have been deposited by the addition of phosphine to the deposition atmospheres (213). Approximately 1 atom % of chlorine was found in the as-deposited films. Annealing in nitrogen at temperatures above 750 °C caused chlorine to difluse from the film surface, grain growth to occur, and the film resistivity to drop. Such heat treatments were necessary to achieve integrated-circuit-quality films. 

The motivation of this study was to establish a relationship between the structure of the films and their electrical and optical characteristics, which strongly depend on the indium concentration [11, 20], The conclusion of this study is clearly beyond the scope of this review. But the polarized EXAFS study has clearly evidenced that the indium doping affects the grain growth process by increasing the surface anisotropy of films. Finally this example shows that we have powerful experimental but also theoretical tools to study surfaces or oriented systems. 

The doped and intrinsic silicon layers (p, i, n) are packed between a TCO front contact and a highly reflective back contact. The back contact is usually either a metal like silver (Ag) or aluminum (Al), or a TCO/metal double layer structure. The latter has been shown to reduce absorption losses due to a better grain growth of Ag layers onto ZnO. Additionally, absorption losses due to surface plasmons in the metal film have to be considered [33]. Both effects result in a higher reflectivity of the TCO/Ag back reflector. In module production, magnetron sputtered ZnO is usually applied as TCO-material for the back reflector in combination with either Ag (highest reflectivity) or Al (low cost). Depending on the deposition sequence of the doped and intrinsic silicon layers, one speaks of so-called superstrate (p-i-n) or substrate (n-i-p) cell structure (see Fig. 8.4). 

P. Dhaudari, Grain Growth and Stress Rehef in Thin Films, Journal of Vacuum Science and Technology, VoXSi oA), 1972,p.520. 

CMP removal rate (RR) of electrodeposited Cu film was found to increase by 35% over time after plating. The RR increase was attributed to Cu film hardness reduction of 43% and grain growth fix)m the initial O.lum at as-deposit to lum at the final stage at room temperature. The removal rate increase will translate to variations in manufacturing environment and are therefore unacceptable. It was found that annealing at -100C for 5 minutes in inert gas will stabilize Cu films and provide consistent CMP removal rate. 

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