User Manual

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1
Siemens Building Technologies
Cerberus Division
01.2002
1 Fire protection concept
1.1 Our aim
The early detection of incipient fire in clean rooms and in the related utility installa-
tions for the safety of personnel and to limit damage.
A clean room is an area in a company where strict air cleanliness standards are main-
tained. A fire in such an area can cause major economic damage.
This protection concept will give you a basic knowledge of the special air handling aspects
of clean rooms and, using examples, present possible solutions for early fire detection.
The fire protection concept presented here applies purely to areas where the clean
room is protected from contamination in the surrounding area by overpressure
(see also chapter 2).
1.2 Facts
The semiconductor industry is one of the most modern in the world. Chips with the finest
microstructures are produced in clean rooms by means of complex processes and installa-
tions. The processes involve considerable risk. Semiconductor production is comparable
with a chemicals plant with many hazardous materials and sources of danger. 350 chemi-
cals in 75 different processes are typical. The following dangerous chemicals and gases *
)
are commonly used:
– acids (HF, H
2
SO
4
, H
3
PO
4
, HCL etc.)
– solvents (Isopropanol, N-Bromo-Acetamide, Xylene etc.)
– metals (As, Sb)
– gases (SiH
4
, PH
3
, AsH
3
, HCl, Cl
2
, H
2
, O
2
).
SiH
4,
silane, for example, can combust spontaneously at concentrations of 1.37% – 96% at
room temperature and can also react explosively with other materials. Radiotherapy equip-
ment, high voltage installations and the like are additional sources of danger.
The processes must be carried out in an exceptionally clean environment. For this reason
the quality requirements for the air in the clean room are extremely high.
Fires in clean rooms can have catastrophic consequences. Even the slightest contamina-
tion through fire aerosols and corrosive gases can endanger production and if the fire de-
velops to any size it can shut down production for weeks.
According to Factory Mutual, the average amount of damage caused per incident in the
semiconductor industry in 1995 exceeded $8 million. In addition to this, incidents involving
damage were recorded for every tenth insured building. By comparison with this, one inci-
dent involving an average amount of less than $250,000 was recorded for every 100 in-
sured industrial buildings. As this example shows, the level of damage expected in clean
rooms greatly exceeds the usual limits. It represents a new risk dimension.
*
)
For further information about dangerous chemicals and gases refer to chapter 7