DS 7-7R 17-12R Semiconductor Fabrication Facilities ... - FM Global

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7-7R 2.1.1.1 Silane Silane, which is discussed in detail under Section 2.6, more so than other gases used in semiconductor manufacturing, can lead to severe exposures. It is a stable gas but is pyrophoric, that is, under certain conditions, it can spontaneously ignite. The trend today is to use higher concentrations of silane. In addition, silane is being used as a carrier gas for arsine and phosphine. In the event of a leak, the pyrophoric silane reaction would likely consume the poisonous arsine and phosphine. The process properties of silane mixtures can be found in Table 2. Percent Silane Table 2. Silane Mixtures Carrier Gas Hazard 2.0 Inert Flammable >1.0 Any Flammable >2.0 Hydrogen Pyrophoric >3.0 Inert Pyrophoric 2.1.1.2 Dichlorosilane Dichlorosilane (DCS) is a pyrophoric, toxic, corrosive and colorless gas. Its boiling point is 47°F (8.3°C). The minimum autoignition temperature is 111°F (44°C). DCS is used for a variety of chemical vapor deposition reactions. It is used to form epitaxial layers as well as silicon dioxide, silicon nitride, and polysilicon layers. DCS tends to slowly decompose during storage. This is only a problem in the presence of heat and/or catalysts such as amines or Lewis acids. Decomposition products are silane, monochlorosilane, trichlorosilane and silicon tetrachloride. Due to the corrosive nature of DCS, there is concern regarding its effect on carbon steel cylinders and valves. Therefore, no more than a 12-month shelf life is recommended. Minimum ignition energy (MIE) is 0.0154 mJ (second to hydrogen which is the lowest measured MIE). Combustion produces amorphous silica, water, hydrogen chloride gas, and chlorine. Due to its low vapor pressure (9 psi [0.6 bar]) and concern about proper distribution flow, there is a preference in the industry to locate process cylinders of DCS close to the process tool to minimize the length of distribution pipe. However, this results in process DCS cylinders being located in service chases and subfabs which, in turn, results in an unnecessary exposure to the cleanroom, process tools and related support equipment. Some facilities have overcome the low vapor pressure distribution flow issue by insulating and heat tracing the distribution piping. This allows them to locate process DCS cylinders in properly arranged process gas distribution rooms which do not expose the cleanroom, process tools and related support equipment. 2.1.1.3 Trichlorosilane Another chlorinated silane gas is trichlorosilane (TCS) which is used to produce polycrystalline silicon and to form silicon epitaxial layers. With a boiling point of 89°F (32°C) and a flash point of 7°F (–14°C), TCS is normally found in liquid form. 2.1.1.4 Chlorine Trifluoride REFERENCE DOCUMENT 17-12R SEMICONDUCTOR FABRICATION FACILITIES Page 6 Chlorine trifluoride is used to clean chemical vapor deposition (CVD) reactor chambers. It is a corrosive, colorless gas and a powerful oxidizer, which immediately ignites many organic compounds. It also ignites many metals at elevated temperatures, and reacts violently with water. Chlorine trifluoride is hypergolic, which means that it ignites organic fuels on contact. No ignition source or air is required. The installation of automatic sprinklers in gas cabinets containing chlorine trifluoride is not recommended due to its extreme reactivity with water. The reaction products with water include hydrogen fluoride, chlorine dioxide, hydrogen chloride and other hazardous by-products. In the event of a release, water is the major ©2003 Factory Mutual Insurance Company. All rights reserved.
eaction source for chlorine trifluoride because it is normally readily available in the surroundings. Exposure to chlorine trifluoride in the presence of a relative humidity of 50% has been shown to cause significant corrosion in a short period of time to materials. Since chlorine trifluoride decomposes instantaneously when exposed to atmospheric conditions (moist air), the compound in its original form cannot be monitored or detected. The presence of chlorine trifluoride must be sensed through one of its by-products. Electrochemical detectors or paper tapes are two methods being successfully used to detect chlorine trifluoride through its by-products. Hydrogen fluoride (HF) is the major by-product of chlorine trifluoride reactions with moist air, however, detectors based on hydrogen fluoride do not have the capability to sense very low concentrations of HF (less than 0.1 ppm). For this reason, detectors calibrated for HF should only be used to detect high quantity chlorine trifluoride leaks. In critical areas where life safety is required, detectors calibrated for chlorine dioxide provide the most accurate indication of chlorine trifluoride. Detection based on HF, HCL, chlorine or fluorine are not recommended as they will not provide accurate detection at TLV or sub-TLV values of chlorine trifluoride. In air, chlorine trifluoride reacts rapidly with oxygen and water to form highly toxic and corrosive products, such as hydrogen fluoride, hydrogen chloride, fluorine, chlorine and chlorine dioxide. 2.1.1.5 Hydrogen Hydrogen gas is widely used and is the primary carrier for the dopant gases such as silane, phosphine, arsine, diborane, etc. It can be found in both cylinder and cryogenic form. Even though the flammable and explosive properties of hydrogen are well documented, there have been numerous adverse incidents involving this gas. These incidents generally involve some kind of leak and ignition of the gas by many different sources. 2.1.2 Photoresist, Developer and Rinse REFERENCE DOCUMENT 7-7R SEMICONDUCTOR FABRICATION FACILITIES 17-12R Page 7 ‘‘Photoresist,’’ its developer, and rinse make up the largest volume of flammable liquids used within the semiconductor fabrication area. A list of flammable/combustible liquids used in fabrication can be found in Table 3. The handling of flammable photoresist, developer and rinse in plastic containers represents a severe fire hazard. Large scale fire tests by FM Approvals have shown flammable liquids in plastic containers to be a severe fire hazard and special fire protection is warranted in accordance with Loss Prevention Data Sheet 7-29. ©2003 Factory Mutual Insurance Company. All rights reserved.
Page 1 and 2: REFERENCE DOCUMENT FM Global 7-7R P
Page 3 and 4: 1.0 SCOPE This reference data sheet
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Page 9 and 10: 3 SiH4 Silane 3 SiH2Cl2 Dichlorosil
Page 11 and 12: for dielectric and dissolved gas in
Page 13 and 14: 2.2 Fire Hazards of Wet Benches Wet
Page 15 and 16: FM Global Research does not limit v
Page 17 and 18: REFERENCE DOCUMENT 7-7R SEMICONDUCT
Page 21 and 22: The final step in wafer form of int
Page 25 and 26: 3.3.1 Chemical Mechanical Polish Ch
Page 27 and 28: Chill Water Supply/Return Heating W
Page 29 and 30: Typically, these codes have separat
Page 31 and 32: Conformance can be demonstrated by
Page 33 and 34: 5.0 SEMICONDUCTOR TERMINOLOGY Align
Page 35 and 36: Junction—The interface at which t
Page 37 and 38: Soft Baking—A heating process use

DS 7-7R 17-12R Semiconductor Fabrication Facilities ... - FM Global

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