semi合集-English.pdf - 第6837页

SEMI S2-0703a E © SEMI 1991, 2004 66 RELATED INFORMATION 7 DOCUMENTATION OF IONIZING RADI ATION (SECTION 24 AND APPENDIX 4) INCLUDING RATIONALE FOR CHANGES NOTICE : This rel ated information i s not an of ficial part of …

SEMI S2-0703a

RELATED INFORMATION 6

CONTINUOUS HAZARDOUS GAS DETECTION

NOTICE: This related information is not an official part of SEMI S2 and was derived from practical application by

task force members. This related information was approved for publication by vote of the responsible committee on

October 21, 1999.

R6-1 Scope — This related information provides a list

of gases for which continuous monitoring is

recommended, and another list of gases for which

continuous monitoring may be recommended

depending on variables listed below. The list is not

intended to be exhaustive (gases that do not appear on

the list may need to be continuously monitored).

R6-2 Intent — The purpose of this Related Information

is to provide equipment manufacturers with an

indication as to what gases are currently continuously

monitored by device manufacturers, as guidance for

when it may be appropriate to provide an interface (see

also Section 23).

R6-3 The following variables should be taken into

consideration when determining the necessity for

continuous monitoring:

 Chemical toxicity,

 Warning property/OEL ratio,

 Delivery pressure,

 LEL,

 Flow rate of potential leak,

 Engineering controls in place, and

 Concentration.

Monitoring Recommended Monitoring May Be

Recommended

ammonia

arsine

boron trifluoride

bromine

carbon dioxide

carbon monoxide

carbon tetrabromide

chlorine

diborane

dichlorosilane

disilane

fluorine

germane

germanium tetrafluoride

flammable mixtures

containing hydrogen

hydrogen bromide

hydrogen chloride

hydrogen fluoride

hydrogen selenide

hydrogen sulfide

Methane

methyl chloride

methyl fluoride

nitric oxide

nitrogen dioxide

nitrous oxide

nitrogen trifluoride

ozone

phosphine

silane

silicon tetrachloride

silicon tetrafluoride

sulfur dioxide

trichlorosilane

tungsten hexafluoride

SEMI S2-0703a

RELATED INFORMATION 7

DOCUMENTATION OF IONIZING RADIATION (SECTION 24 AND

APPENDIX 4) INCLUDING RATIONALE FOR CHANGES

NOTICE: This related information is not an official part of SEMI S2 and was derived from practical application by

task force members. This related information was approved for publication by vote of the responsible committee on

October 21, 1999.

R7-1 International Background Information

R7-1.1 The International Atomic Energy Agency

(IAEA)

Mailing address:

P.O. Box 100

Wagramerstrasse 5

A-1400, Vienna, Austria

Telephone: (+43-1) 2060-0; Facsimile: (+43-1) 20607:

E-mail: Official.Mail@iaea.org

R7-1.2 Basic approaches to radiation protection are

consistent all over the world. The International

Commission on Radiation Protection (ICRP)

recommends that any exposure above the natural

background radiation should be kept as low as

reasonably achievable, but below the individual dose

limits. The total individual dose limit for radiation

workers over 5 years is 100 mSv, and for members of

the general public, is 1 mSv per year. These dose limits

have been established based on a prudent approach by

assuming that there is no threshold dose below which

there would be no effect. This hypothesis proposes that

any additional dose will cause a proportional increase in

the chance of a health effect. This relationship has not

yet been established in the low dose range where the

dose limits have been set.

R7-1.3 The ICRP and the IAEA recommend the

individual dose must be kept as low as reasonably

achievable and consideration must be given to the

presence of other sources that may cause simultaneous

radiation exposure to the same group of the public.

Also, allowance for future sources or practices must be

kept in mind so that the total dose received by an

individual member of the public does not exceed the

dose limit.

R7-2 How Does This Apply to the

Semiconductor Industry?

R7-2.1 A person who can potentially be exposed to

ionizing radiation during the normal course of business

in excess of the annual limit for the general public

should be considered a radiation worker. A radiation

worker is trained to recognize and protect him or

herself from the hazards of ionizing radiation. They

may require exposure monitoring to determine

compliance with local radiation regulations. Radiation

workers are covered by a radiation safety program. A

radiation safety program is an administrative control.

Engineering controls minimize the need for spending

resources in a large scale radiation program.

R7-2.2 The exposure limit for the radiation worker is

20 millisievert (2000 millirem) per year. Based on a 40

hour/week, 50 week/working year basis, the allowable

ionizing radiation emissions are 10 microsieverts/hr

(1.0 millirem/hr). This exposure rate should be

evaluated as an emission rate from any accessible

surface of the equipment (the closest approach to the

surface that the radiation is penetrating).

R7-2.3 Maintenance technicians for radiation machines

should be participants in the radiation safety program as

radiation workers. The equipment should be designed to

allow maintenance technicians access to areas that do

not exceed 10 microsieverts/hr.

R7-2.4 Service technicians for radiation machines

should be participants in their employer’s radiation

safety program as radiation workers. The equipment

should be designed to allow service technicians access

to areas that exceed the 10 microsievert per hour level

when operating, but not while the radiation is present.

R7-2.5 The person operating radiation producing

equipment (Operator) should not be considered a

radiation worker. The emission limit for the operator

accessible areas is recommended to be 20% of the

occupational limit. The maximum allowable ionizing

radiation emissions for operator accessible areas is

recommended to be 2 microsieverts/hr (0.2

millirem/hr). This exposure rate should be evaluated as

an emission rate from any surface foreseeably

accessible by an operator of the equipment, and should

be measured as an instantaneous rate.

R7-3 Definitions

R7-3.1 accessible — a significant part of the whole

body, head, or eyes.

R7-3.2 bremsstrahlung — is radiation produced by

slowing of charged particles. The term means “braking

radiation.”

SEMI S2-0703a

NOTE 1: During design of shielding, the properties of the

radiation should be considered as well as the properties of the

shielding materials. Bremsstrahlung production should be

minimized. Some shielding materials are considered

hazardous materials. These hazardous properties should be

considered and identified.

R7-3.3 radiation machine — means any device

capable of producing ionizing radiation except those

devices with radioactive material as the only source of

radiation.

R7-3.4 radiation producing machine — is a radiation

machine that produces ionizing radiation as a by-

product of the process it uses, e.g., ion implanter or

scanning electron microscope.

R7-3.5 radiation worker — “worker” means an

individual engaged in radiation related work under a

license or certificate of registration issued by the

Agency and controlled by a licensee or registrant, but

does not include the licensee or registrant.

R7-3.6 radioactive material – means any material

(solid, liquid, or gas) that emits ionizing radiation

spontaneously.

R7-3.7 X-ray machine — is a radiation machine that

generates X-rays as a primary function of the

equipment. This category of radiation machine has a

specific limit due to the existence of performance

standards against which the equipment is evaluated.

The equipment must be below this limit to be sold in

some parts of the world.

R7-3.8 X-rays — are produced with electricity and

therefore can be turned off. X-rays seem to be the most

prevalent radiation type in semiconductor

manufacturing equipment. They are produced when

charged particles are slowed or stopped. This slowing

results in “bremsstrahlung.” The majority of the

equipment does not intentionally produce X-rays. This

energy is a by-product of the process.

R7-4 Radioactive Materials

R7-4.1 Gamma radiation is a by-product of atomic

transformations (decay) and is a release of energy from

the nucleus. This radiation energy must be shielded

since there is no off switch.

R7-4.2 Radioactive Materials are controlled by

licensing. There are quantities of certain radioactive

materials that are exempt from regulation. These

sources should be identified.

R7-4.3 External radiation hazards from radioactive

materials include gamma rays. These are controlled and

evaluated much like the X-rays.

R7-4.4 Internal radiation hazards from radioactive

materials include Alpha and Beta particles. Radioactive

materials ingested or inhaled can be metabolized or

damage surrounding tissue. Allowable levels of

airborne radioactivity and radionuclide intakes are

specified in regulations. The objective is still to

maintain all exposure to ionizing radiation (internal and

external) as low as reasonably achievable, but always

less than the allowable regulatory limits.