semi合集-English.pdf - 第5426页
SEMI M59-0305 © SEMI 2005 7 5.50 gett ering — the process that immobilizes impurities at locations away fro m the region of the specimen to be investigated. 5.51 glo bal flatness — the TIR or the maximum FPD relative to …
SEMI M59-0305 © SEMI 2005 6
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.
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5.64 lot — for the purposes of commercial exchange of silicon wafers, (a) all of the wafers of nominally identical
size and characteristics contained in a single shipment, or (b) subdivisions of large shipments consisting of wafers as
above that have been identified by the supplier as constituting a lot.
5.65 macroscratch — a scratch that is visible to the unaided eye under either incandescent (high intensity) or
fluorescent (diffuse) illumination.
5.65.1 Discussion — The number of macroscratches on a wafer is equal to the count of scratches seen under diffuse
illumination.
5.66 majority carrier — type of charge carrier constituting more than one half the total charge-carrier concentration
(e.g., holes in p-type material).
5.67 maximum FPD — the largest of the absolute values of the focal plane deviations.
5.68 microroughness — surface roughness components with spacing between irregularities (spatial wavelength)
less than about 100 µm.
5.69 microscratch — a scratch that is not visible to the unaided eye under fluorescent (diffuse) illumination but is
visible to the unaided eye under incandescent (high intensity) illumination.
5.69.1 Discussion — The number of microscratches on a wafer is the difference of the count of scratches seen under
high intensity illumination and the count of scratches seen under diffuse illumination.
5.70 Miller indices, of a crystallographic plane — the smallest integers proportional to the reciprocals of the
intercepts of the plane on the three crystal axes of unit length.
5.71 minority carrier — type of charge carrier constituting less than one half the total charge-carrier concentration
(e.g., electrons in p-type material).
5.72 mound — on a semiconductor wafer surface, irregularly shaped projection with one or more irregularly
developed facets.
5.73 nanotopography — the non-planar deviation of a wafer surface within a spatial wavelength range of
approximately 0.2 mm to 20 mm.
5.74 notch — an intentionally fabricated indent of specified shape and dimensions on a silicon wafer oriented such
that the diameter passing through the center of the notch is parallel with a specified low index crystal direction.
5.75 orange peel — large-featured, roughened type of wafer surface visible to the unaided eye.
5.76 orientation, of a single crystal surface — the crystallographic plane, described in terms of its Miller indices,
with which the surface is ideally coincident.
5.76.1 Discussion — In semiconductor single crystals, where the surface of a wafer cut from the crystal usually
corresponds closely (within a degree or several degrees) to a low index plane, such as a (100) or (111) plane, the
surface orientation is frequently described in terms of the maximum angular deviation of the mechanically prepared
surface from the low index crystallographic plane.
5.77 orthogonal misorientation—in wafers cut intentionally “off orientation,” the angle between the projection of
the vector normal to the wafer surface onto a {111} plane and the projection on that plane of the nearest <110>
direction.
5.78 particle — a small, discrete piece of foreign material or silicon not connected crystallographically to the
wafer.
5.78.1 Discussion — Particles may be pieces of solid material or condensate from liquids or gases. Particles are
observed by automated inspection as laser light-scattering events, but they may also be observed visually under high
intensity illumination as points of light or studied by other methods, including scanning electron microscopy.
Particles on wafer surfaces can usually be removed by non-etching cleaning.
5.79 pit — a depression in a wafer surface where sloped sides of the depression meet the surface in a
distinguishable manner in contrast to the sides of a dimple, which are rounded.