Page 269 - Electrical Engineering Dictionary

exponent (1) the field within a floating- to the light intensity times the exposure time.
point format that determines the power to Also called exposure dose.
which the mantissa should be raised.
(2) a shorthand notation for representing exposure field the area of a wafer that is
repeated multiplication of the same base. 2 4 exposed at one time by the exposure tool.
is exponential notation to multiply two by
2
itself four times : 2 = 2 · 2 · 2 · 2 = 16. 4 express feeder a feeder to which laterals
is called the exponent, indicating how many are connected only at some distance from the
times the number 2, called the base, is used substation. These thus traverse areas fed by
as a factor. other feeders and are used to supply concen-
(3) the component of a binary floating- trated loads or new subdivisions. See feeder,
point number that signifies the integer power lateral.
of two by which the significand is multiplied
in determining the value of the represented expulsion fuse a fuse used on primary dis-
number. tribution lines which extinguishes the arc that
results when it blows by explosively ejecting
exponential distribution a probability the fuse wire from its enclosure.
density function having the following expo-
nential behavior: expulsion tube arrester a gapped light-
ning arrester which establishes the power-
−λx
λe x ≥ 0
f(x) = follow arc in a tube lined with a substance
0 x< 0
which generates a sufficient quantity of gas
when heated to blow out the arc. See power
where λ> 0. This distribution can de-
follow, lightning arrestor.
scribe a number of physical phenomena, such
as the time for a radioactive nucleus to de-
expurgated code a code constructed from
cay, or the time for a component to fail.
another code by deleting one or more code-
Seealsoprobabilitydensityfunction, Cauchy
words from the original code.
distribution, Gaussian distribution.
exponential stability (1) the property of extended binary-coded-decimal inter-
an asymptotically stable equilibrium solution change code (EBCDIC) character code
that guarantees an exponentially decreasing developed by IBM and used in mainframe
(to zero) norm in time of the difference be- computers. It is closely related to the Hol-
tween the solution and the equilibrium point. lerith code for punched cards.
(2) a special case of uniform asymptotic
extended code a code constructed from
stability of an equilibrium point of ˙ x =
f(t, x). another code by adding additional symbols
to each codeword. Thus an (n, k) original
exposure the process of subjecting a resist code becomes an (n + 1,k) code after the
to light energy (or electron energy in the case adding of one redundant symbol.
of electron beam lithography) for the purpose
of causing chemical change in the resist. extended industry standard architecture
(EISA) a bus architecture designed for
exposure dose See exposure energy. PCs using an Intel 80386, 80486, or Pentium
microprocessor. EISA buses are 32 bits wide
exposure energy the amount of energy and support multiprocessing. The EISA bus
(perunitarea)thatthephotoresistissubjected was designed by IBM competitors to com-
to upon exposure by a lithographic exposure pete with micro channel architecture (MCA).
system. For optical lithography, it is equal EISA and MCA are not compatible with each

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2000 by CRC Press LLC