semi合集-English.pdf - 第5427页
SEMI M59-0305 © SEMI 2005 8 5.64 lot — for the purposes of commercial exchange of silicon wafers, (a) all of the wafers of nominally identical size and characte ristics contained i n a single shipment, or (b) su bdivisio…
SEMI M59-0305 © SEMI 2005 7
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.
SEMI M59-0305 © SEMI 2005 8
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.
SEMI M59-0305 © SEMI 2005 9
5.80 point defect — a localized crystal defect such as a lattice vacancy, interstitial atom, or substitutional impurity.
Contrast with light point defect.
5.81 preferential etch — a selective etch that etches regions of different crystal strain or conductivity at different
rates, used to delineate crystal defects or regions of differing conductivity on wafer surfaces.
5.82 primary flat — the flat of longest length on the wafer, oriented such that the chord is parallel with a specified
low index crystal plane; sometimes called major flat.
5.83 radial gradient — not preferred; use resistivity variation.
5.84 reference plane — a plane defined by one of the following:
three points at specified locations on the front or back surface of the wafer,
the least squares fit to the front or median surface of the wafer using all points within the FQA,
the least squares fit to the front surface of the wafer using all points within a site, or
an ideal back surface (equivalent to the ideally flat chuck surface that contacts the wafer).
5.84.1 Discussion — For flatness measurement, the specified reference plane is chosen with due regard for the
capabilities of the imaging system. Front surface or back surface reference planes should be selected depending on
the wafer mounting system. If the wafer cannot be gimbaled in the imaging system, a back surface reference plane
should be specified. For shape measurement, the reference plane to be used is spelled out in the applicable test
method.
5.85 reference plane deviation, RPD — the distance perpendicular to the reference plane between the reference
plane and the wafer surface being measured.
5.86 resistivity, (electrical),
, [·cm] — the measure of difficulty with which charged carriers flow through a
material; the reciprocal of conductivity.
5.86.1 Discussion — the resistivity of a semiconductor or other material is the ratio of the potential gradient (electric
field) parallel with the current to the current density.
5.87 rms area microroughness, R
qA
— the root mean square of the topographic deviations of a surface Z(x,y) from
the mean surface taken within the (rectangular) evaluation area A
e
= L
x
L
y
.
5.87.1 Discussion — The rms area microroughness is one of several statistical metrics that can be used to describe
surface topography; definitions for other metrics and for such concepts as mean surface and evaluation area may be
found in ANSI/ASME B46.1 and ISO 4287/1.
5.87.2 The function R
qA
is related to a two-dimensional measurement of the surface profile as follows:
2/1
00
2
dd),(
1
x
y
L
L
e
qA
yxyxZ
A
R (1)
The digital approximation of R
qA
for a surface profile consisting of N by M data points equally spaced along the x
and y directions, respectively, is:
2/1
11
2
1
M
i
N
j
ijqA
Z
NM
R (2)
5.87.3 Experimentally, the profile is always limited by the spatial bandwidth of the measurement. In the x direction,
the profile length is L
x
divided into N equally spaced points; the lower spatial frequency limit for f
x
can never be less
than 1/L
x
and the upper spatial frequency limit can never be greater than the Nyquist limit, N/2L
x
. Similarly, in the y
direction, the profile length is L
y
divided into M equally spaced points; the lower frequency limit for f
y
can never be
less than 1/L
y
and the upper spatial frequency limit can never be greater than the Nyquist limit, M/2L
y
. Practical
limits to the spatial bandwidth are governed by considerations similar to those for the one-dimensional case (see
¶5.88.4).