Thermally Grown Silicon Dioxide

Disadvantages of thermally grown silicon dioxide are the high deposition temperature of about 960 °C and the exigency of a silicon substrate. Moreover, an adhesion layer of 4-8 nm of nickel is necessary to improve the adhesion of the 30 nm thick gold electrodes deposited on top of the oxide. 

The surface of the pentacene film was examined by atomic force microscopy (AFM). It exhibits crystallites with a diameter of about 250 run in the transistor channel. On the gold surface of the drain and source contacts, the dimensions are twice the size as on silicon dioxide. In comparison with growth studies in [18] where the surface was pretreated by an adhesion promoter, the presented pentacene film consists of very small crystallites. 

In order to improve the transistor eharaeteristies by inereasing the pentaeene grain size, the oxide surfaee was eleaned in an oxygen plasma to remove residues of the photoresist that remained on top after the lift-off step. The eleaning is performed direetly before eoating the struetures with the organie material. 

The dieleetrie surfaee was exposed to the oxygen plasma for 30 s at 100 W in a parallel-plate reaetor. A longer proeess time eould result in etehing of the sili-eon dioxide, whieh would be eounterproduetive. 

After this treatment a 30 nm thiek pentaeene layer was deposited onto the samples at a proeess pressure of 8 x 10 mbar and a deposition rate of about 0.1 nm/s, resulting in a pentaeene film with a grain size of about 1 pm, as eon-firmed by AFM [19]. 

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As an example of the latter technique, Volkman et al. demonstrated the feasibility of using spin-cast zinc oxide nanoparticles encapsulated in 1-dodecanethiol to fabricate a functional transistor.44 The zinc oxide was deposited on a thermally grown silicon dioxide layer on a conventional silicon wafer, with thermally evaporated gold source and drain electrodes. As reported, the process requires very small particles (3nm or less) and a 400 °C forming gas anneal. A similar approach was also reported by Petrat, demonstrating n-channel thin-film transistor operation using a nanoparticle solution of zinc oxide dispersed onto a thermally grown silicon dioxide layer on a conventional... 

Hofmann and Thomas (31) have discussed the effect of ion bombardment on thermally grown silicon dioxide. XPS showed that small changes in the surface chemistry were observable. The Si 2p and 0 Is peaks were seen to broaden due to ion damage trtilch presumably Increased bond-angle disorder resulting in charge redistribution. 

An analysed transistor was produced on silicon and thermally grown silicon dioxide as the gate dielectric where the layer thickness was 127 nm. The pen-tacene film was evaporated in high vacuum at 6 x 10 mbar at a deposition rate of 0.1 nm/s. During the deposition the substrate temperature was 25 °C. 

Tb-implanted thermally grown silicon dioxide film, and (iii) Tb-doped alumina xerogels fabricated onto monocrystalline silicon. Thus, the terbium-doped alumina xerogel/PAA structure was proposed as a basis for green room-temperature luminescent images [17]. 

Compared with vitreous quartz, porosity and strain in films cause the 1085 cm 1 and 460 cm 1 absorption bands to be broadened and shifted to lower wave numbers, whereas the 800 cm 1 band is shifted to higher wave numbers. As can be seen in Fig. 4, after proper densification (i.e. heat treatment between 800 and 1000°C), a pure SiC>2 film deposited with no oxygen deficiency by low-temperature CVD becomes essentially indistinguishable from high-temperature thermally grown silicon dioxide... 

Perhaps the best studied gate dielectric treatment is the application of silanes (e.g. octadecyltrichlorosilane or OTS) to thermally grown silicon dioxide. While this structure is limited in its utility in integrated circuits, it provides a well controlled system in which to study structure/function relationships that can then be extrapolated to more practical, but less controlled, integrated structures (e.g. PECVD or PVD deposited oxides). 

A fresh surface of thermally grown silicon dioxide, it must be pointed out, is hydrophobic. However, it quickly reacts with water vapor in the atmosphere to form silanol (Si—OH) and gradually becomes hydrophilic. In fact, the chemical vapor deposition of silicon dioxide forms only a silanolated surface. Being fairly hydrophobic, resists do not adhere well to hydrophilic surfaces such as Si02-These surfaces contain hydroxyl groups as illustrated in Reaction [11.1]. The adhesion failure of resist films on such surfaces is often observed in the course of development or wet etching. As a result, a surface treatment to promote adhesion is necessary before the resist film is deposited on such surfaces. ... 

The sensors used were Ir-Si02-Si structures made on p-type silicon with 100 nm thermally grown silicon dioxide. Iridium was evaporated with an electron-gun through a metal mask having a circular hole of 2 mm diameter. The nominal thickness of the iridium film... 

In principle, each of the components of the OFET can be an organic material, and several fully organic examples have been reported [9-14]. In practice, however, one or more of the components is usually non-organic. A particularly common screening device setup comprises n-doped silicon as the gate electrode, with a layer of thermally grown silicon dioxide on top as the dielectric layer, and patterned source and drain electrodes. The dielectric provides a very smooth and homogeneous surface with which to deposit... 

Deposit gold onto glass substrates or silicone wafers with a layer of thermally grown silicone dioxide. 

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