Clean room technology

Aerosols, fog and smog, foams, water purification and sewage treatment cloud seeding and clean room technology (see also Vignettes 1.1 and VIII)... 

In this section we focus on four specific environmental problems coal combustion aerosol formation, dynamics of atmospheric aerosols, the chemical characterization of particles, and the role of aerosols in clean room technology or so-called microcontamination control. For the reader interested in an introduction to aerosol science, we recommend three texts [6-8]. 

There are a large number of potential sources for particles to fall onto a wafer. Advanced tool design and proper selection of clean room technology can be very effective in reducing or eliminating this type of defect. In addition, it is desirable to eliminate manual intervention. The use of minienvironment around the tools and closed wafer-handling cassettes such as FOUP (front opening unified pod) are proven effective. These types of particles are more frequently seen in small clean rooms where wafers are handled manually. 

Clean Room Standards and Room Classification Clean room technology is the most typical feature of aseptic manufacture. The major regulatory sources of guidance to appropriate technology and air standards for aseptic filling [2,3,4]... 

Clearly there are issues here that the pharmaceutical industry needs to address. Particles of the smaller sizes specilied for measurement in the Clean Room Standards are not of direct concern to particulate contamination issues facing manufacturers of sterile pharmaceuticals. Furthermore, it is the quality of clean room technology that is the factor of greatest importance to the pharmaceutical industry, of which the attainment of clean room classification is merely an indirect index. In these circumstances a major increase in the amount of testing required to claim compliance with a particular classification offers no benefit to the industry, and may indeed unnecessarily increase testing costs, downtime, etc. 

Regarding the workability the common constituents in ambient air are aerosols composed mainly of solid and liquid particulate matter which can cause serious contamination problems at trace and ultra trace levels. The values in Table 5 demonstrate the significance of clean room conditions for precise and accurate determinations at these levels.Thus, for prevention of foreign contamination through Pb, Cu, Zn the clean room technology is a must. ... 

VDI 2083 Sheet 9 (Draft) Clean room technology, electronics- and pharmaceuticals industries [10]... 

IMS can be used for chemical analysis of vapours from electronics packaging [287]. IMS-QMS has been used to analyse headspace vapours in sealed electronic packages [275,288] and to follow outgassing of polymers [287]. Various types of photoresist solvents, phtha-late plasticisers and other polymer additives, such as BHT, were detected. Other applications of IMS in semiconductor technology involve failure analysis control of the efficiency of cleaning and etching steps characterisation of process media and surveillance of the atmosphere of clean rooms. 

A survey of the environmental control and monitoring technology used in several experimental studies indicated significant limitations in experimental control capability. There are seven controlled-environment chambers or clean-room facilities in the United States for human exposure (community air pollution inhalation) from which studies have been reported. Another is under construction at the University of North Carolina in association with the epa at Chapel Hill. There are three chambers in Canada of similar design. 

The use of radiation within a parenteral facility would have been considered unthinkable prior to the start of the twenty-first century. While y irradiation is typically a contracted service provided off-site, electron beam sterilization advances can make the installation of an in-house (and generally an in-line) system a real possibility. An in-line system would be utilized similarly to the gas/vapor systems described above for treatment of external surfaces for entry into either a clean room or isolator-based aseptic processing facility. The use of this same technology for terminal sterilization is also possible [1], Association for the Advancement of Medical Instrumentation (AAMI)/ISO 11137 provides widely accepted guidance on the development and validation of radiation sterilization processes. 

The liquid solution CCVD process does not deposit droplets (these evaporate in the flame environment) or powders as in traditional thermal spray processes. The CCVD technology is drastically different from spray pyrolysis In spray pyrolysis, a liquid mixture is sprayed onto a heated substrate, while CCVD atomizes a precursor solution into sub-micron droplets followed by vaporization of said droplets. The resulting coating capabilities and properties described hereafter qualifies CCVD as a true vapor deposition process. For example, depositions are not line-of-sight limited and achieve epitaxy, 10 nm dielectric coatings onto silicon wafers in a Class 100 clean room resulted... 

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