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SEMI P33-0998 © SEMI 1998 10 camera is projected onto a ph otoplate, attached to the stage, a nd exposed i n as many positions as requ ired by moving th e stage between exposu res. T he product of a photorepeater is the …

SEMI P33-0998 © SEMI 19989

etch time — the time required for the removal of a

coating in an etching medium.

etchant — the chemically reactive solution used for

removal of unwanted metallic coating from a substrate.

field — the background area of a device is defined as

the area not being acted upon during the fabrication

process. Thus, if a mask is to be used to produce metal

interconnects, the area representing non-metal is the

“field.” The image polarity is named by the appearance

of this field; thus, clear field, dark (opaque) field. This

definition is very carefully stated because, in some

devices, their gross appearance is very deceiving in that

“field” cannot always be denoted as the major area.

Some devices may have diffusion of buried layers, for

instance, covering 80% of the area, the remaining 20%

being the field. Some knowledge of the fabrication

process is essential when determining field, as many of

these ambiguous conditions exist where the field is less

than 50% of the area. (ANT: active area; geometry;

trace: diffusion area.)

film adhesive — adhesive between frame and film.

film thickness, dirt — fingerprint; mark touched by

something; stain by liquid.

film thickness, particle — the particle state materials

that can be distinguished from the film itself on the film

surface or inside the film.

film thickness, pinhole — a small opening completely

through a polymer film.

fixer — a chemical solution which makes an image

permanent. In the case of silver emulsion processes, it

dissolves and removes the unexposed/undeveloped

silver halide crystals so that further darkening of the

image cannot occur.

frame adhesive — adhesive between frame and

photomask.

functional element — any contiguous fragment of a

device that is necessary to the electrical operation of the

finished device. Examples include diffused areas,

traces, gates, contacts, etc.; excludes scribe lines,

alignment marks, labels, etc. (SYN: active geometry.)

gel slug — a piece of clear, dried gelatin that has been

trapped in a silver/gelatin emulsion during coating. A

gel slug has the appearance, under a microscope, of a

clear lens-like lump, generally 0.5 – 2 mils in size, and

about twice as long as wide.

isolation layer — a partitioning, especially of bipolar

devices, usually by diffusion, to electrically insulate

functional components of an integrated circuit device.

Isolation masks are usually layer 1 or 2, and

characterized by thin lines defining open boxes all over

the die area. (SYN: isolation mask.)

latent image — the invisible image formed on any

photosensitive material after exposure. It requires some

type of development to produce a useful, visible image.

layer — one of a sequential series of overlaying

photomasks that make up a device series.

mask set — the complete series of masks for all layers,

necessary to fabricate any given device.

master drawing — the original drawing from which the

artwork is made.

master mask — original photomask, at 1× (final) scale,

generated with a photorepeater from which submasters

are printed. (SYN: master.)

matrix — the rectangular arrangement of die on a

photomask. (SYN: array.)

mechanical strength — the physical condition a pellicle

must meet to withstand a specified force from a blow-

off gun without suffering any damage to the film.

mouse bite — see mouse nip.

mouse nip — in semiconductor imaging technology, a

semicircular intrusion.

objective lens — in a microscope system, it is the lens

closest to the test specimen (object). Usually provides

the greatest amount of the total magnification and also

limits system resolution. Most commonly several

objectives, in typical powers of 10×, 20×, and 40×, are

mounted on a turret for rapid magnification changes.

See also ocular.

ocular — the set of microscope lenses closest to the

observer’s eye that produces final magnification of

microscope. It usually contains graticules or filar-

measuring apparatus. See also objective lens.

opacity — a direct measure of the light-stopping power

of a semitransparent medium, as glass photographic

emulsion or a thin chrome coating. Represented as the

reciprocal of transmittance, O = 1/T. The common

logarithm of opacity if used as Optical Density. D =

Log

pellicle — a thin, optically transparent film, typically of

nitrocellulose, attached to, supported by a frame, and

attached to a photomask (or photomask reticle). NOTE:

Its purpose is to seal out contaminants and reduce

printed defects caused by contamination in the image

plane of an optical exposure system.

photorepeater — a combination of a high-resolution

reduction (usually 10× or 5×) camera and a

programmable precision stage. The image from the

SEMI P33-0998 © SEMI 1998 10

camera is projected onto a photoplate, attached to the

stage, and exposed in as many positions as required by

moving the stage between exposures. The product of a

photorepeater is the master mask. (SYN: image

repeater; step-and-repeat camera.)

printing — the transfer of an image from one surface

(substrate) onto another at 1× scale. Usually “printing”

refers to the contact method, but it also can be

accomplished using a 1-to-1 projection optical system.

(SYN: contact printing.)

printing, contact — photoprinting photomask patterns

by exposure of a photosensitive material coated on a

supporting substrate to radiation passing through the

photomask, which is in contact with the photosensitive

material.

printing, off-contact — see printing, proximity.

printing, projection — a method of optically projecting

an image onto a photosensitive material, thus

eliminating the need for photomask/photosensitive-

coating contact.

printing, proximity — photoprinting photomask

patterns by exposure of photosensitive material coated

on a supporting substrate to radiation passing through

the photomask which is in the proximity of, but not in

contact with, the photosensitive material being exposed.

reduction camera — a mechanism used to optically

reduce the size of images and record them

photographically. In two-step reduction, a copy camera

is used for the range of 100× to 1000× reduced to 10×;

the photorepeater reduces from 5× or 10× to 1×. Both

are reduction cameras. See also photorepeater.

registration mark — a mark used to control placement

of one layer relative to another.

repetitive defect — a defect (spot, pinhole, protrusion,

or intrusion) introduced on the reticle so that in

generating a master, it reproduces on every die.

reversal process — a photographic emulsion process

that produces an image which is the same as the input

image (i.e., clear areas remain clear, and opaque remain

opaque). It is named ‘reversal’ because it yields the

‘reverse’ of the standard ‘negative’ process.

Accomplished by developing the negative image,

destroying this image by bleaching, and then

subsequently developing all the original silver halide

that represents the positive image. (SYN: positive-

acting, process, positive process. ANT: negative acting

process, normal process.)

rotation, of array — whole array is properly arranged

(die relative to die), but placed on a blank which is

rotationally mis-aligned. May occur during stepping or

contact printing.

rotation, of die — on a master, misplacement of die by

an angular displacement around the Z-axis. Usually

caused by mispositioning of the reticle in a

photorepeater so that it does not lie parallel to X- and

Y-axis of stage travel.

run-in — a die placement error, where the die

increment is less than the design dimension. This can

occur during stepping, due to nonlinearity of

miscalibration of the photorepeater stage scan scale, or

during contact printing due to plate warpage.

shelf life — the period of time, at specified conditions

of storage, in which the physical and chemical

properties that affect a material’s performance remain

acceptable.

smear — a large area of partially removed coating or

deposited foreign material.

space — area between image geometries; field between

close-lying images. The space is often specified as the

critical dimension. (SYN: field. ANT: digitized area;

geometry.)

spinner — a device for holding a substrate and spinning

it at a controlled rate of speed (usually 1000 to 6000

RPM), for applying extremely thin coating, as with

photoresist.

submaster — a photomask printed in limited quantities

from masters, and from which the working plates are

printed. Used to reduce wear and tear on masters.

test device — a simplified, functional device (of the

same process type as the majority die), inserted in

several positions in any array, used for process control

and monitoring during wafer fabrication.

torn image — image broken by movement of the image

medium. Most often seen on emulsion images.

variable aperture — an aperture whose open area may

be increased or decreased by movement of the elements

forming the aperture.

visual defects — defects that can be identified by a

skilled observer (with or without the aid of a

microscope) without having to measure or compare

(e.g., pinholes, slugs, spots, protrusions, etc.).

working plate — mask used selectively to expose

photoresist on a wafer for IC fabrication. Usually

printed from submasters or masters, thus preserving the

master from excessive handling damage.

NOTICE: These standards do not purport to address

safety issues, if any, associated with their use. It is the

responsibility of the user of these standards to establish

appropriate safety and health practices and determine

the applicability of regulatory limitations prior to use.

SEMI makes no warranties or representations as to the

suitability of the standards set forth herein for any

particular application. The determination of the

suitability of the standard 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. These standards are subject to

change without notice.

The user’s attention is called to the possibility that

compliance with this standard may require use of

copyrighted material or of an invention covered by

patent rights. By publication of this standard, SEMI

takes no position respecting the validity of any patent

rights or copyrights asserted in connection with any

item mentioned in this standard. Users of this standard

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.

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