Contamination electronic devices

In some cases, the degree of fluorine contamination of tantalum and niobium oxides containing increased fluorine levels is not very critical to the later application of the oxides. Applications related to the manufacturing of optic and electronic devices, however, require significant limitations of the fluorine content of tantalum and niobium oxides. 

All standard cleaning processes for silicon wafers are performed in water-based solutions, with the exception of acetone or (isopropyl alcohol, IPA) treatments, which are mainly used to remove resist or other organic contaminants. The most common cleaning procedure for silicon wafers in electronic device manufacturing is the deionized (DI) water rinse. This and other common cleaning solutions for silicon, such as the SCI, the SC2 [Kel], the SPM [Ko7] and the HF dip do remove silicon from the wafer surface, but at very low rates. The etch rate of a cleaning solution is usually well below 1 nm min-1. 

Contamination of silicon wafers by heavy metals is a major cause of low yields in the manufacture of electronic devices. Concentrations in the order of 1011 cm-3 [Ha2] are sufficient to affect the device performance, because impurity atoms constitute recombination centers for minority carriers and thereby reduce their lifetime [Scl7]. In addition, precipitates caused by contaminants may affect gate oxide quality. Note that a contamination of 1011 cnT3 corresponds to a pinhead of iron (1 mm3) dissolved in a swimming pool of silicon (850 m3). Such minute contamination levels are far below the detection limit of the standard analytical techniques used in chemistry. The best way to detect such traces of contaminants is to measure the induced change in electronic properties itself, such as the oxide defect density or the minority carrier lifetime, respectively diffusion length. 

Silicon s tetravalent pyramid crystalline structure, similar to tetravalent carbon, results in a great variety of compounds with many practical uses. Crystals of sihcon that have been contaminated with impurities (arsenic or boron) are used as semiconductors in the computer and electronics industries. Silicon semiconductors made possible the invention of transistors at the Bell Labs in 1947. Transistors use layers of crystals that regulate the flow of electric current. Over the past half-century, transistors have replaced the vacuum tubes in radios, TVs, and other electronic equipment that reduces both the devices size and the heat produced by the electronic devices. 

Our consistent need to improve our daily lives also led to unanticipated industrial developments. For example, the production of automobiles led to expansion of the oil production (or vice versa) and metal working industries, both of which account for pollution by several compounds cited on the contaminant list. The chemical processing industry has been responsible for many items we now consider the essentials of modem life. From plastics to modem electronic devices, the chemical industry has guided and benefited from developments and also exerted colinear effects on the contamination of air and water. Again, the development of remediation technologies is needed to establish an acceptable equilibrium. 

Tacticity is required for the synthesis of crystalline thin polysilane films used for optical and semiconductor devices. Modern synthetic routes allow control over the conformation and tacticity of polysilane molecules used as precursors for thin layers of photoresists, photoconductors and nonlinear optical phases in complex semiconductor and (opto)electronic devices. These properties can be exploited only if the synthesis method ensures a minimal level of contamination, especially with oxygen and metals, and special care is taken to limit electronic-grade polysilanes to a level of contamination on the order of a few ppm in the case of oxygen and in the ppb range for metals. The reactivity of polysilane toward oxygen has forced placing the devices in a helium environment during measurement procedures.36... 

Mass spectrometry has become more useful In the support of electronic development and manufacturing processes. Fourier transform mass spectrometry, the latest advance in this analytical method, Is another step forward in versatility, sensitivity and reproducibility in analytical characterization, qualification and quantification of raw materials and contaminants as used in electronic devices. A review will be provided of basic instrument hardware and interfacing, significant operating parameters and limitations, and special inlet systems. Emphasis will be placed on material evaluation, process control and failure analysis. Data handling will be reviewed using appropriate examples encountered in material and failure analysis. 

Surface science techniques have expanded their application in industry in the last few years for just these reasons — the nature of the surface has been recognised as an important factor in the performance of many materials. This is especially the case in the electronic device industry where low levels of surface contamination can severely deteriorate electronic conductivity and barrier properties. 

The chemical modification of surfaces and films i essential in the manufacture of integrated circuits. Patterns and material must be transferred to substrate surfaces and removed from them. As the dimensions of advanced electronic devices shrink to the submicron and molecular scale, properties of the processing techniques become increasingly critical. Characteristics such as low temperatures, low levels of induced dam. ge and contamination, and molecular scale selectivity and controllabilit] are essential. The use of radiation-induced chemistry is desirable if it can be conducted at lower temperatures and with smaller levels of damage and contamination than particle impact and thermal methods. 

Silicon nitride as a passivation layer on top of an electronic circuit or a metal structure is an excellent diffusion barrier against water and protects the electronic device from organic and metallic (e.g., Na, K) contaminants. Silicon nitride is also used as a masking layer for wet anisotropic etching of silicon (in KOH), as part of a dielectric membrane, and for mechanical protection in micromechanics during face-down handling of the front of electronics while processing the back of the wafer, a silicon nitride passivation layer prevents defects and scratches on the sensitive front side. 

Conformal Coatings. To protect printed circuitry and electronic devices from contaminants such as moisture, particulates, and fumes, they are covered with thin films of polymers. These polymers may be applied as "all solids" formulations or as solvent-containing systems, or, as in a special case, by polymerization of a vapor deposited monomer. 

In the last process step, fine particles are removed by the microfiltration unit. In the manufacture of highly integrated electronic devices, particles from the solvents used in these processes must be removed to improve product yields and suppress wafer contamination defects. For example, particles with >0.05-pm diameter should be removed to the extent of less than 10 particles per milliliter from solvents used in 16-Mbit level production lines [247]. Accordingly, the level of the microfiltration unit affects total system performance therefore, the unit should be equipped with an appropriate filtration membrane, although only a few membranes with sufficient performance are available [248]. In the solvent a very low level of dissolved metals and low total organic carbon (TOC) is desired. Moreover, high chemical resistance of the filtration membrane is also needed. 

Systems YES-G500 etching systems 40-50 kHz electronic devices, circuit assemblies Wire bond surface preparation Contaminants flux removal 2 powered shelves... 

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