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SEMI E5-1104 © SEMI 1982, 2004 253 Table 24 SECS-II Units of Measure Identifiers Unit Identifier Equivalence Prefix Allowed Suffix Allowed Description Non-dimensional quantities (pure numbers) null string None No No For …

SEMI E5-1104 © SEMI 1982, 2004 252

Table 23

Prefix Name Multiplicative Factor Prefix Symbol

exa 10^18 E

peta 10^15 P

Tera 10^12 T

giga 10^9 G

mega 10^6 M

kilo 10^3 k

hecto 10^2 h

deka (deca) 10^1 da

deci 10^-1 d

centi 10^-2 c

milli 10^-3 m

micro 10^-6 u

nano 10^-9 n

pico 10^-12 p

femto 10^-15 f

atto 10^-18 a

12.2.4 Any SECS-II identifier which Section 12.4

indicates as being capable of taking on a suffix value

may have a numeric string appended to it. This decimal

value allows the user to identify one of a family of

symbol names with only the generic symbol name of

the family being defined in Section 12.4. The meaning

of a numeric suffix is dependent on the particular

symbol with which it is being used and must be defined

in the description section of the symbol definition.

12.2.5 Arithmetic expressions of units of measure

identifiers are recognized by SECS-II as units symbols

if they are formed by the following rules:

1. All units identifiers in the expression are SECS-II

units identifiers defined in Section 12.4 or SECS-II

prefixed units identifiers as defined above.

2. Exponentiation is denoted by a circumflex (^)

between the identifier to be operated on and the

exponent. Exponents may be positive or negative

values. A negative value is denoted by a unary

minus sign (-) between the circumflex and

exponent. For positive values, the exponent will

immediately follow the circumflex (A^2 or A^-2).

3. Multiplication of units identifiers is expressed by

an asterisk (*) positioned between the factors to be

multiplied (A*B).

4. Division of units identifiers is expressed by a slash

(/) positioned between the dividend and divisor.

Division may also be expressed as the product of

the dividend and the divisor with a negative

exponent (A/B or A*B^-1).

5. Parentheses may be used to specify the order in

which the arithmetic operations will be performed.

6. Within expressions or sub-expressions where

parentheses do not specify the order of operations,

exponentiation will be carried out first, followed by

left-to-right evaluation of all multiplication and

division that is (A*B^-2*30*C^2) is equivalent to

(((A/(B^2))*30)*(C^2)).

12.3 Compliance — For the units of measure

information to have any value and to be in compliance

with SECS-II, equipment and host system

manufacturers must ensure that only units symbols

allowed by SECS-II are used by their systems. In those

instances where SECS-II does not provide a units

symbol required for a particular application, the

manufacturer requiring the new symbol may submit a

proposal to the SEMI Communications Subcommittee

requesting the enhancement. A proposal must include

all the information provided by each entry of Section

12.4 as described above.

12.3.1 A proposal must undergo the full approval cycle

as prescribed by SECS-II for amending a standard

(acceptance by committee, balloting, etc.). As a result,

the proposal should be submitted as soon as possible, so

that sufficient time is available to complete the standard

amendment process and to notify all interested parties

of the change before the product requiring the new

symbol becomes available for use in a manufacturing

facility.

12.4 SECS-II Units of Measure Identifiers — All units

of measure symbols recognized by SECS-II are defined

in this section or are compound symbols based on the

identifiers defined here and formed by the rules speci-

fied in Section 12.2. Portions of the information

provided below have been obtained from ANSI/IEEE

260-1978, ANSI X3.5-1976, ISO 2955-1974(E),

Webster’s New World Collegiate Dictionary (copyright

1977), and the CRC Handbook of Chemistry and

Physics (52nd edition for 1971-1972).

SEMI E5-1104 © SEMI 1982, 2004 253

Table 24 SECS-II Units of Measure Identifiers

Unit Identifier Equivalence Prefix

Allowed

Suffix

Allowed

Description

Non-dimensional

quantities (pure

numbers)

null string None No No For all quantities which have no associated unit of

measure, a zero length (null) text string is the

appropriate ‘identifier’ to use when units of

measure information is required.

ampere A None Yes No SI unit of electric current.

ampere (turn) AT None Yes No SI unit of magnetomotive force.

angstrom Ang m*10^-10 Yes No Unit of length used when measuring wavelength

of light.

atmosphere, standard atm 101325*Pa No No A unit of pressure.

atmosphere, technical at kgf/cm^2 No No A unit of pressure.

atomic mass unit

(unified)

u 1.660531*10^-27*kg No No One twelfth the mass of an atom of carbon 12

nuclide.

bar bar 100*kPa Yes No CGS unit of pressure.

barn barn 10^-28*m^2 Yes No Unit for measuring capture cross sections of

elements.

barrel (petroleum) bbl 42*gal or 158.99*1 No No A unit of volume.

baud Bd bit/s Yes No Telecommunications measure of data transfer rate

equivalent to one bit of information transferred

per second.

bel B None Yes No The logarithm of the ratio of two power signals.

Becquerel Bq None Yes No SI unit of activity of a radionuclide.

bit bit None Yes No A unit of computer information equivalent to the

choice between two alternatives (as yes or no, on

or off).

boat boat None No Yes Special SECS generic unit corresponding to a

holder of wafers or packages with discrete

positions. The unit capacity is specified by the

symbol’s suffix, if provided. Otherwise, the

capacity is situation-dependent.

British thermal unit Btu 1054.35*J No No The quantity of heat required to raise the

temperature of one pound of water one degree

Fahrenheit at or near 39.2˚F.

byte byte 8*bit Yes No Unit of storage for computer memory.

calorie (International

Table)

callIT 4.1868*J Yes No Defined by the 1929 International Stream Table

Conference to be 1/860 international joules or

l/859.858 joules.

calorie

(thermochemical)

cal 4.l840*J Yes No Unit of energy defined by the NBS to be 4.184

joules. Also, called the gram calorie.

candela cd None Yes No SI unit of luminous intensity.

candle cd None Yes No Alternate name for candela.

carrier carrier None No Yes Special SECS generic unit corresponding to a

holder for substrates, wafers or wafer frames. The

unit capacity is specified by the symbol’s suffix, i

provided. Otherwise, the capacity is situation-

dependent.

cassette css None No Yes Special SECS generic unit corresponding to a

holder for wafers or wafer frames. The unit

capacity is specified by the symbol’s suffix, if

provided. Otherwise, the capacity is situation-

dependent.

Coulomb C A*s Yes No SI unit of electric charge.

Unit Identifier Equivalence Prefix

Allowed

Suffix

Allowed

Description

curie Ci 3.7*l0^l0*Bq No No A unit of activity of radionuclide.

cycle c None Yes No Unit equivalent to one complete performance of a

periodic process.

darcy D cP*(cm/s)(cm/atm)

or 0.986923*um^2

No No Unit of permeability of a porous medium. By

traditional definition, a permeability of one darcy

will permit a flow of 1 cm^3/s of fluid of 1 cP

viscosity through an area of 1 cm^2 under a

pressure gradient of 1 atm/cm.

day (mean solar) d 24*h No No The period required for the Earth to complete one

rotation about its axis.

degree (plane angle) deg pi/180*rad No No One three hundred sixtieth part of the

circumference of a circle.

degree Celsius degC None No No Unit of temperature where 0˚C corresponds to the

freezing point of water and l00˚C corresponds to

the boiling point at standard atmospheric

conditions.

degree Fahrenheit degF None No No Unit of temperature where 32˚F corresponds to

the freezing point of water and 212˚F corresponds

to the boiling point at standard atmospheric

conditions.

degree Kelvin K None No No SI unit of temperature.

die die None No No Special SECS generic unit corresponding to an

individual integrated circuit both on a wafer and

after wafer separation. Also referred to as a bar or

chip.

dyne dyn 10^-5*N Yes No Unit of force in the cgs system. One dyne is the

force required to provide a one grain mass with an

acceleration of 1 cm/s^2.

electronvolt eV l.60209*10^-19*J Yes No Energy acquired by a small particle carrying a

unit electronic charge when it falls through a

potential difference of one volt.

erg erg l0^-7*J Yes No Unit of work or energy in the cgs system. One

erg is equal to the work done or energy expended

to exert a force of one dyne through a distance of

1 cm.

farad F A*s/V Yes No SI unit of capacitance.

foot ft 12*in No No English unit of length.

footcandle Fc lm/ft^2 No No Unit of illuminance. Also called lumen per square

foot.

footlambert FL (1/pi)*cd/ft^2 No No A unit of luminance. One lumen per square foot

leaves a surface whose luminance is one

footlambert in all directions within a hemisphere.

gal Gal cm/s^2 Yes No A unit of acceleration used especially for values

of gravity.

gallon (US) gal 23l*in^3 or 4*qt or

3.7854*1

No No United States version of English system unit of

volume.

gallon (UK) galUK 4.546l*l No No United Kingdom version of English system unit o

volume.

gauss G Mx/cm^2 Yes No Electromagnetic CGS unit of magnetic flux

density.

gilbert Gb l0/(4*pi)*AT Yes No Electromagnetic CGS unit of magnetomotive

force.

grain gr .0022857l43*oz No No English unit of weight.

gram g None Yes No One thousandth of the SI unit of mass.