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SEMI S18-1102 © SEMI 2002 16 corrosive, these po rts should be compatibl e with the hazards presented. 17.3.3 Due to the hazards as sociated with silane family gas deposits, only maintenance w orkers trained to handle th…

SEMI S18-1102 © SEMI 2002

• recommended duct size and flow volumes, based

on the suppliers recommended base process,

• information on potential maintenance issues

associated with the process (such as silicate

deposits and reactive by-product generation),

• The probable hazards that would be generated by

exposure of open ducts to air during maintenance

activities,

• maximum distance from the reaction chamber to

the vacuum pump, and

• maximum distance from the pump to the exhaust

connection or the point-of-use abatement.

16.5.2 The need to route the residual gas and by-

products to the proper gas treatment system may require

consideration of separate pump systems for

incompatible gases.

16.6 Other Information

16.6.1 Manuals as defined in SEMI S13, should

include information and training requirement on silane

family gases, their hazards, and recommended

protective measures.

16.6.2 Hazard warning labels should be designed in

conformance to SEMI S1. Where such labels are to be

placed should be decided per SEMI S2.

17 Exhaust Systems and Plumbing

17.1 Design

17.1.1 Enclosure Exhaust System — Exhaust piping for

the gas panel enclosure or the pump enclosure may be

required to be separated from heat exhaust line to

prevent the possibility for mixing of incompatible

chemistries before dilution.

NOTE 50: Separation of exhaust systems may be required by

certain jurisdictions.

17.1.1.1 Air velocity for an enclosure should be

calculated to minimize collection of silane family gases

into pockets.

NOTE 51: Information to decide what amount of air velocity

should be needed is provided through Related Information 2.

Document such as CGA P32-2000 and NFPA318-2000

provides similar information.

NOTE 52: Some regulations may require minimum velocities

until new research (SSA Journal, Spring and Winter 1998)

can be incorporated into the regulations. This minimum

velocity is not less than 1.0 m/sec for the overall enclosure,

and air velocity across any potential leakage point is not less

than 0.5 m/sec.

NOTE 53: Recommendations for gas cylinder cabinet

exhaust provided in Related Information 2 can also be used

for enclosures within process equipment. For the purpose of

enclosure exhaust calculations, gas delivery pressure to the

enclosure should be used as the “source pressure” in Figure 3

of Related Information 2.

17.1.2 Process Exhaust Systems

17.1.2.1 Materials of construction should be

compatible with the hazards presented by the silane

family gases present.

17.1.2.2 Materials for exhaust piping containing silane

family gases should be compatible with the byproducts

and should provide protection from heat and reactions,

which may be present when silane family gases exit a

reaction chamber.

17.1.2.3 No combustible joint compound (including

adhesive or tape) should be used to seal joints.

17.1.2.4 Process exhaust piping should withstand the

maximum potential pressure generated by the reaction

of respective silane family gases in a reasonably

foreseeable worst case, single-point failure at the

process equipment.

17.1.3 Metal-gasket face-seal fittings should be used

wherever possible. Compression fittings lead to

increased risk of leaks, especially when subjected to

expansion and contraction by internally burning and

extinguishing silane family gases.

17.2 Protective Devices

17.2.1 Mechanical fittings in pressurized exhaust or

treatment system should be enclosed in exhausted

enclosures, like any supply piping. Leaking can be

caused by the result of assembly and disassembly

during pump and treatment system maintenance.

17.3 Maintainability

17.3.1 Maintenance personnel should inspect for

liquids and solids collecting in exhaust ducts to prevent

accidents resulting from the build-up of reaction

products.

17.3.2 Ports for chemical sampling should be provided

in order to enable inspection of deposits and sampling

of gas composition and concentration in the exhaust

duct.

17.3.2.1 Ports, if not connected to a sampling device,

should have a stop valve and should be sealed with a

cap or plug.

17.3.2.2 This monitoring should be performed

periodically to insure gas composition and quantities

have not generated new hazards and to characterize gas

deposits and ensure they are being removed.

17.3.2.3 View ports also require periodic cleaning to

provide for adequate viewing capability. If the gas is

SEMI S18-1102 © SEMI 2002

corrosive, these ports should be compatible with the

hazards presented.

17.3.3 Due to the hazards associated with silane family

gas deposits, only maintenance workers trained to

handle the potential for reactions, small fires or

explosions should be allowed to perform maintenance

on exhaust ducts for silane family gases.

17.3.3.1 Maintenance management should investigate

the thickness and composition of the deposits and

establish the proper method of maintenance.

17.3.3.2 If the investigation indicates the deposit is

reactive or unstable, a procedure to stabilize or

neutralize the deposit before opening the duct to air

should be implemented.

17.3.3.3 Equipment suppliers should also notify users

that stabilizing or neutralizing procedures provided in

the maintenance manuals might not work for exhaust

lines with multiple silane family gas-using systems

attached.

17.3.4 The exhaust piping should be designed to have a

means of monitoring the exhaust line for determining if

the exhaust line is blocked.

18 Exhaust Treatment Systems

18.1 Selection

18.1.1 Refer to SEMI F5 for techniques and

information to determine the appropriate abatement

(exhaust treatment) system.

18.1.2 The user should determine the composition,

concentration, absolute amount per minute and possible

phases (solid, liquid or gas) of all chemicals, to be

treated, before requesting quotations on abatement

systems. This information is very important to design

an appropriate abatement system.

18.1.3 The information should be provided for normal

operation and all reasonable foreseeable failures.

18.2 Absorbent Systems — Gas leak detection may

also be needed as breakthrough detection for absorbent

systems. To ensure that each gas treatment system

functions properly, it should have a gas detection and

alarm system that detects breakthrough of absorbent.

The location of sample points should be appropriate to

detect breakthrough of the absorbent according to the

treatment system instructions.

18.2.1 When breakthrough is detected, the gas source

which supplies silane family gas or other hazardous gas

to the equipment connected to the failed abatement

system should be shut off. Absorbent in the failed

abatement system should be replaced immediately.

Alternatively a switching system can be employed to

switch to a back-up absorbent bed or redundant

treatment system.

18.3 Design

18.3.1 Point-of-use gas abatement systems are

described in SEMI F5.

18.3.2 A gas abatement system should be selected with

consideration for both equipment and facilities.

18.3.3 Some gas abatement systems need enclosures.

Such enclosures should be monitored for leaks. Upon

leak detection, an alarm should be activated and the gas

source should be shut down.

18.3.4 When abnormal status of an abatement system

is detected, the gas source(s) which supply gas to the

equipment connected to the gas abatement system

should be stopped.

18.3.5 In a combustion-type gas treatment system, a

flame detector, an airflow rate sensor, an exhaust

temperature monitor and a gas concentration monitor at

the outlet could be used for detecting abnormal status of

those parameters.

18.3.6 If a wet-type gas abatement system is used

downstream of an adsorbent or combustion gas

treatment system, it should be designed to prevent

reverse flow of water into the upstream system.

Monitoring to determine any abnormal operating

condition of the wet-type system should be provided.

18.3.6.1 The system should also be equipped with a

water leak sensor.

18.4 Operation

NOTE 54: The concentrations of exhaust gas at the outlet of

a gas abatement system must not exceed the maximum

allowable concentrations established by laws and regulations

of the region where the system is used, even in an emergency

situation.

18.4.1 Adequate performance of the abatement system

should be ensured at all times.

NOTE 55: Constant monitoring of the concentration at the

outlet may be required by some jurisdictions. The source gas

may also have to be shut down if the emissions reach the

maximum allowable amount.

NOTE 56: It may not be necessary for abatement systems to

be constantly “on-line” in some jurisdictions when gas is

“stored” and not “dispensed”. In such a situation, the

abatement system may be allowed to start when a leak is

detected.

18.5 Maintenance

18.5.1 The gas abatement system manufacturer should

provide the user with recommended maintenance

procedures considering the characteristics of silane

family gases and by-products in written form, even if

the manufacturer maintains the system. Maintenance

workers should be provided training as specified by the

manufacturer.

18.5.2 Interlocks or bypasses should be provided at

appropriate locations to stop the flow of process

effluent to the exhaust treatment system during

maintenance or malfunction.

18.5.3 After a malfunction alarm is activated, the

abatement system should not be automatically restarted.

The cause of the alarm should be carefully inspected

and maintenance or service of system should be

performed if necessary.

19 Related Documents

NOTE 57: As listed or revised, all documents cited shall be

the latest publications of adopted standards.

19.1 Compressed Gas Association

CGA P-32  Safe Storage and Handling of Silane and

Silane Mixtures

19.2 SEMATECH, Inc. / International SEMATECH,

Inc

96083168A-ENG  Effects of Leak Size and

Geometry on Releases of 100% Silane (ESHB001)

96013067A-ENG  Ignition Characteristics of

Releases of 100% Silane (ESHB001)

95092976A-ENG  Comparative Analysis of a Silane

Cylinder Delivery System and a Bulk Silane

Installation (ESHB001)

94062405A-ENG  Silane Safety Improvement

Project S71 Final Report

19.3 Factory Mutual Property Loss Prevention Data

Sheet, 7-7

 Semiconductor Fabrication Facilities

NOTICE: SEMI makes no warranties or

representations as to the suitability of the guideline set

9 SEMATECH Inc./International SEMATECH Inc., 2706 Montopolis

Drive, Austin, TX 78741-6499 (or www.sematech.org)

10 Factory Mutual Engineering, 1151 Boston-Providence Turnpike

(PO Box 9102) Norwood, MA, 02062 or http://www.fmglobal.com;

(877) 364-6726 (toll free for U.S. & Canada) or (781) 255-4681, or

print out an order formand fax it to us at (781) 255-4359.

forth herein for any particular application. The

determination of the suitability of the guideline is solely

the responsibility of the user. Users are cautioned to

refer to manufacturer’s instructions, product labels,

product data sheets, and other relevant literature

respecting any materials mentioned herein. This

guideline is subject to change without notice.

The user’s attention is called to the possibility that

compliance with this guideline may require use of

copyrighted material or of an invention covered by

patent rights. By publication of this guideline, SEMI

takes no position respecting the validity of any patent

rights or copyrights asserted in connection with any

item mentioned in this guideline. Users of this

guideline are expressly advised that determination of

any such patent rights or copyrights, and the risk of

infringement of such rights, are entirely their own

responsibility.