ISO 14644-8 assigns ISO classification levels to be used to specify the limits of AMC concentrations within a cleanroom and associated controlled environment. For classification purposes, this part of ISO 14644 is limited to a designated range of AMC concentrations between 10° and 10-12 g/munder cleanroom operational conditions.

According to this standard, AMCs are categorized into the following 8 substance groups:

Category Definitions
Acids Substance whose chemical reaction characteristic is to establish new bonds by the acceptance of electron pairs.
Bases Substance whose chemical reaction characteristics is to establish new bonds by the donating of electron pairs.
Biotoxic Contaminant substance that is obnoxious to the development and preservation of the life of organisms, microorganisms, tissues or individual cells.
Condensables Substance capable of depositing on a surface by condensation under cleanroom operating condi­tions.
Corrosive Substance that causes destructive chemical change of a surface.
Dopant Substance that after absorption and/or diffusion,is incorporated in the bulk of a product and is capable of changing the properties of materials,even in trace amounts.
Organic Substance based on carbon and also containing hydrogen,with or without oxygen,nitrogen or other elements.
Oxidant Substance that,upon deposition onto a surface or product of interest,results in the formation of an oxide (02/03) or participates in a redox reaction.
ISO-AMC Class Concentration g/m3 Concentration µg/m3 Concentration ng/m3
0 100 106 (1 000 000) 109 (1 000 000 000)
-1 10-1 105 (100 000) 108 (100 000 000)
-2 10-2 104(10 000) 107 (10 000 000)
-3 10-3 103(1000) 106 (1 000 000)
-4 10-4 102 (100) 105  (100 000)
-5 10-5 101 (10) 104(10 000)
-6 10-6 100 (1) 103 (1000)
-7 10-7 10-1 (0.1) 102 (100)
-8 10-8 10-2 (0.01) 101 (10)
-9 10-9 10-3 (0.001) 100 (1)
-10 10-10 10-4 (0.0001) 10-1 (0.1)
-11 10-11 10-5  (0.00001) 10-2 (0.01)
-12 10-12 10-6 (0.000001) 10-3 (0.001)

The ISO-AMC decriptor is espressed in the format:

ISO-AMC Class N(X)


N is the ISO-AMC class, which is the logarithmic index of concentration, Cx, expressed in grams per cubic meter and falls within a limiting range of 0 to -12. Intermediate concentrations maybe specified, with 0.1 the smallest permitted increment of N.

X is a contaminant category.

As an example, to express a total airborne concentration of organics, of 10-4 g/m3, the designation is ISO-AMC Class -4 (or)”.

There has been increasing awareness that AMC is a key factor in determining the fabrication process yield in microelectronics. Since 1995, Semiconductor Equipment and Material International (SEMI) have been involving in this and SEMI issued SEMI F21-1102 standard, entitled classification of Air Borne Molecular Contami­nant Levels in Clean Environments’

SEMIF21-1102 specifies four categories of contaminants as follows:

Category Definitions
Acids A corrosive material whose chemical reaction characteristic is that of an electron acceptor
Bases A corrosive material whose chemical reaction characteristic is that of an electron donor.
Condensables A substance (other than water), typically having boiling point above room temperature at atmospheric pressure,capable of condensation on a clean surface.
Dopants A chemical element which modifies the electrical properties of a semi conductive material.

The maximum cumulative gas phase concentrations of the four categories may be different.Classification is determined by the maximum allowable total gas phase concentration of each category of material. The combination of a quantitative class for each of the four categories yields a classification describing an environment.

Material Category 1* 10* 100* 1000* 10000*
Acids MA-1 MA-10 MA-100 MA-1000 MA-10000
Bases MB-1 MB-10 MB-100 MB-1000 MB-10000
Condensables MC-1 MC-10 MC-100 MC-1000 MC-10000
Dopants MD-1 MD-10 MD-100 MD-1000 MD-10000

The integer following the material category classification indicated the maximum total gas phase concentration in ppt. For example,a category MD-100 has a maximum allowable total concentration of 100 ppt for Dopants category.

Sector Examples Recommended MayAir AMC FIlter Series
Commercial (general odour and light concentration of AMC)


High-rise office building / premises
Odourfil Series, Puro-C, Puro-V


Educational building
Shopping complex
Convention center
Light Duty (medium concentratio of odour and AMC)


Food & beverage processing / Kitchen
Odourfil Series, Puro-C, Puro-V, Puro-M, Puro-F


Semiconductor cleanroom
Pharmaceutical cleanroom
Chemical research laboratary
Heavy Duty (high concentration of odour and AMC)


Pulp and paper industry
Odourfil Series, Puro-C, Puro-V, Puro-M


Oil and gas refinery
Mining industry
Chemical production facility