semi合集-English.pdf - 第5425页
SEMI M59-0305 © SEMI 2005 6 intensity illumin ation. Some SSISs have sensors for repo rting XLSs. XLSs can be observed as increased haze under dark field conditions. Under bright field conditions, an XLS can be observed …
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5.20 crater — surface feature with irregular closed ridges and smooth central regions.
5.21 Crow’s foot — intersecting cracks in a pattern resembling a “crow's foot” (Y) on (111) surfaces and a cross (+)
on (100) surfaces.
5.22 crystal defect — departure from the ideal arrangement of atoms in a crystal.
5.23 crystal indices — see Miller indices.
5.24 crystal originated pit, COP — a small pit or plurality of small pits introduced during crystal growth that act as
an LLS when they intersect the surface of a wafer.
5.24.1 Discussion — Because they act in some ways similarly to particles when viewed with an SSIS, this defect
was originally called a crystal originated particle. Modern SSISs can, however, generally distinguish COPs from
particles. Surface cleaning or light etching frequently increases the size and number of COPs observed, when they
are present.
5.25 crystallographic notation — a symbolism based on Miller indices used to label planes and directions in a
crystal as follows:
plane (111)
family of planes {111}
direction [111]
family of directions <111>
5.26 denuded zone — a volume in a wafer, usually located just under the front surface, in which the oxygen content
has been lowered so that the bulk microdefect (oxide precipitate) density is reduced.
5.27 diameter, of a semiconductor wafer — the linear dimension across the surface of a circular wafer that contains
the wafer center and excludes flats or other peripheral fiduciary geometries.
5.28 dimple — a shallow depression with gently sloping sides that exhibits a concave, spheroidal shape and is
visible to the unaided eye under proper lighting conditions.
5.29 dislocation etch pit — a pit generated by a preferential etch where a dislocation meets the surface of a wafer.
5.30 donor — an impurity or imperfection in a semiconductor that donates electrons to the conduction band, leading
to electron conduction.
5.31 dopant — a chemical element, usually from the third or fifth columns of the periodic table, incorporated in
trace amounts in a silicon crystal to establish its conductivity type and resistivity.
5.32 dopant striation rings — helical features on the surface of a silicon wafer associated with local variations in
impurity concentration.
5.33 doping, v. — addition of specific impurities to a semiconductor to control the electrical resistivity.
5.34 edge exclusion, nominal, EE — the distance from the FQA boundary to the periphery of a wafer of nominal
dimensions.
5.35 edge profile — on edge contoured wafers (whose edges have been shaped chemically or mechanically), a
description of the contour of the boundary of the wafer that joins the front and back surfaces.
5.36 etch — a solution, a mixture of solutions, or a mixture of gases that attacks the surfaces of a film or substrate,
removing material either selectively or nonselectively.
5.37 etch pit — a pit, resulting from preferential etching, localized on the surface of a wafer at a crystal defect or
stressed region.
5.38 extended light scatterer (XLS) — a feature larger than the spatial resolution of the inspection equipment, on or
in a wafer surface, resulting in increased light scattering intensity relative to that of the surrounding wafer surface.
5.38.1 Discussion — Origins of XLSs include area contamination and unresolved clusters of localized light
scatterers, such as particles or COPs. When oberved by the unaided eye, an XLS can usually be seen under high
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intensity illumination. Some SSISs have sensors for reporting XLSs. XLSs can be observed as increased haze
under dark field conditions. Under bright field conditions, an XLS can be observed as a decrease in the intensity of
the specularly reflected beam, sometimes called a light channel defect.
5.39 extrinsic, adj. — (1) the region in the conductivity-temperature curve where the conduction in a wafer is
dominated by holes or electrons from dopant atoms; (2) a process, such as extrinsic gettering, caused by factors
outside the crystal of the wafer itself.
5.40 fiducial — a flat or a notch on a wafer intended to provide a location referenced to its crystallographic axes.
5.41 fixed quality area, FQA — the central area of a wafer surface, defined by a nominal edge exclusion, EE, over
which the specified values of a parameter apply.
5.41.1 Discussion — The boundary of the FQA is at all points the distance EE away from the periphery of a wafer
of nominal dimensions. The size of the FQA is independent of wafer diameter and flat length tolerances. For the
purposes of defining the FQA, the periphery of a wafer of nominal dimensions at a location with a notch is assumed
to follow the circumference of a circle with diameter equal to the nominal wafer diameter. It may be necessary to
specify exclusion areas where the values of a specified parameter do not apply for regions like: the notch, laser
marks, or where handling/gripping devices contact the wafer.
5.42 flat — a portion of the periphery of a circular wafer that has been removed to a chord; see also primary flat,
secondary flat.
5.43 flat diameter — the linear dimension across the surface of a semiconductor wafer from the center of the flat
through the wafer center to the circumference of the wafer on the opposite edge along the diameter perpendicular to
the flat.
5.43.1 Discussion — The flat diameter is most often associated with the primary flat. In the case of opposing
primary and secondary flats, as occurs on {100} n-type wafers 125 mm and smaller in diameter, the concept of flat
diameter does not apply because the diameter perpendicular to the flats does not intersect the wafer circumference.
5.44 flatness — for wafer surfaces, the deviation of the front surface, expressed in TIR or maximum FPD relative to
a specified reference plane when the back surface of the wafer is ideally flat, as when pulled down by a vacuum onto
an ideally clean flat chuck.
5.44.1 Discussion — The flatness of a wafer may be described as either:
the global flatness,
the maximum value of site flatness as measured on all sites, or
the percentage of sites that have a site flatness equal to or less than a specified value.
NOTE 1: See Appendix 1 of SEMI M1 for a complete discussion of flatness parameters.
5.45 focal plane — the plane perpendicular to the optical axis of an imaging system that contains the focal point of
the imaging system.
5.45.1 Discussion — The reference plane used by an imaging system is coincident with or parallel with the focal
plane. Full field imaging systems employ coincident global focal and reference planes. Partial field imaging
systems employ either coincident site focal and reference planes or displaced site focal and global reference planes.
If the reference plane is not coincident with the focal plane, it is displaced from the focal plane so that the point on
the front surface at a site center lies in the focal plane.
5.46 focal plane deviation, FPD — the distance parallel to the optical axis from a point on the wafer surface to the
focal plane.
5.47 four-point probe — an electrical probe arrangement for determining the resistivity of a material in which
separate pairs of contacts are used (1) for passing current through the specimen and (2) measuring the potential drop
caused by the current.
5.48 front side — not preferred; use front surface.
5.49 front surface — the exposed surface upon which active semiconductor devices have been or will be fabricated.
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5.50 gettering — the process that immobilizes impurities at locations away from the region of the specimen to be
investigated.
5.51 global flatness — the TIR or the maximum FPD relative to a specified reference plane within the FQA.
5.52 gradient, resistivity — not preferred; use resistivity variation.
5.53 groove — a shallow scratch with rounded edges that is usually the remnant of a scratch not completely
removed by polishing.
5.54 haze — non-localized light-scattering resulting from surface topography (microroughness) or from dense
concentrations of surface or near-surface imperfections; see also laser light-scattering event.
5.54.1 Discussion — Haze due to the existence of a collection of imperfections is a mass effect; individual
imperfections of the type that result in haze cannot be readily distinguished by the eye or other optical detection
system without magnification. In a scanning surface inspection system, haze results in a background signal; this
signal and laser light-scattering events together comprise the signal due to light-scattering from a wafer surface.
5.55 hole — a mobile vacancy in the electronic valence structure of a semiconductor that acts like a positive
electron charge with positive mass; the majority carrier in p-type material.
5.56 indent — an edge defect that extends from the front surface to the back surface of a silicon wafer.
5.57 ingot — a cylinder or rectangular solid of polycrystalline or single crystal silicon, generally of slightly irregular
dimensions.
5.57.1 Discussion — Silicon wafers are usually sliced from cylindrical single-crystal ingots that have been ground to
a uniform diameter prior to slicing.
5.58 intrinsic, adj. — (1) the region in the conductivity-temperature curve where the conduction in a wafer is
dominated by hole-electron pairs excited across the forbidden energy gap; (2) a process, such as intrinsic gettering,
caused by factors within the crystal of the wafer itself.
5.59 laser light-scattering event — a signal pulse that exceeds a preset threshold, generated by the interaction of a
laser beam with a discrete scatterer at a wafer surface as sensed by a detector; see also haze.
5.59.1 Discussion — In a scanning surface inspection system, the background signal due to haze and laser light-
scattering events together comprise the signal due to light-scattering from a wafer surface.
5.60 lay — the predominant direction of the surface texture.
5.60.1 Discussion — Although the texture of polished silicon wafers is generally isotropic, some epitaxial wafers
exhibit a pattern of steps and ledges when examined by atomic force microscopy at near atomic resolution.
Contoured wafer edges may also exhibit lay even after polishing.
5.61 light point defect, LPD — not preferred, use localized light-scatterer, LLS.
5.61.1 Discussion — To some, the term light point defect implies a defective part; hence, a search was undertaken
for a more neutral term. Several were tried, and finally, despite some objection to the difficulty of saying the code,
the term localized light scatterer was approved as a replacement. This term is general in nature and can refer to
features detected both visual inspection and by automated inspection using a scanning surface inspection system.
5.62 lineage — a low-angle grain boundary resulting from an array of dislocations.
5.63 localized light-scatterer, LLS — an isolated feature, such as a particle or a pit, on or in a wafer surface,
resulting in increased light-scattering intensity relative to that of the surrounding wafer surface; sometimes called
light point defect.
5.63.1 Discussion — Localized light scatterers of sufficient size appear as points of light under high intensity optical
illumination; these points of light can be observed visually, but the observation is a qualitative one. Localized light
scatterers are observed by automated inspection techniques as laser-light scattering events. Automated inspection
techniques are quantitative in the sense that scatterers with different scattering intensities can be segregated. The
presence of LLS’s does not necessarily decrease the utility of the wafer.