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SEMI P43-0304 © SEMI 2004 5 7.17 measured mean X-Y deviatio n — the difference between the mean values of measured feature widths i n X and Y direct ions, stati ng the same info rmation as fo r measured fe ature width un…

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7.6 measured feature edge — position determined
from the measured signal obtained on the mask feature
edge. For example position determined at a certain
level of the signal, as defined by the bounding box
model of SEMI P35. The same mandatory/optional
information must be stated as for measured feature
width.
7.7 critical dimension (abbreviated to CD) — a user
defined feature width of interest, mainly used for
further qualification. The critical dimension can be
plural. DEFAULT CD is one width and one pitch.
Mandatory information is the nominal feature width
and pitch.
NOTE 7: The ITRS mask table assumes multiple pitches.
7.8 feature width uniformity — the spread of the
distribution of the width of all mask features of a given
design size, selected as detailed hereafter. To be stated
as mandatory information:
• its targeted feature width,
• the criterion used (range, 3-sigma, maximum
deviation, etc.), where sigma stands for standard
deviation. Recommendation: before 3-sigma is
relevant, the distribution needs to be “normal” or
“near normal”, and the number of measurements
should be > 30,
• type and tone of features considered (line, contact,
space, etc. as defined in SEMI P19),
NOTE 8: Several types and/or tones of features could be
combined, but the recommendation is one tone and one
type, DEFAULT is lines for clearfield, spaces for
darkfield).
• all orientations considered (adopting a pre-
determined mask orientation, based on the
coordinate system in Section 6), for example
horizontal and vertical together, horizontal only,
vertical only, including other angles, horizontal-
and-vertical separately, etc. DEFAULT is
horizontal and vertical together,
• the pitch of the feature (or in general: a description
of the surrounding area, see further), e.g., equal
lines and spaces, isolated line, etc., or (if wished,
but not recommended) an interval of pitches, and
NOTE 9: In case of multiple pitches the defined feature
width uniformity would not be proximity free.
DEFAULT is one fixed pitch, to be mentioned. (The
ITRS mask table assumes multiple pitches.)
• The considered area of interest on the mask.
7.9 measured feature width uniformity — measured
value of feature width uniformity, stating as mandatory
information in addition to that of measured feature
width and feature width uniformity:
• the number of measurement points used,
• the measured area on the mask,
and as optional information:
• the spatial distribution of measurement locations,
e.g., by their coordinates. DEFAULT is spread
evenly over the measurement area.
7.10 (measured) CD uniformity — the special case of
feature width uniformity where the selected feature is
the critical dimension.
7.11 feature mean-to-target — the difference between
the mean width of features, selected as detailed, and
the targeted feature width, stating the same information
as for feature width uniformity. (DEFAULT: selecting
the same information and values as for feature width
uniformity.)
7.12 measured feature mean-to-target — the difference
between the mean of measured feature widths and the
targeted feature width, stating the same information as
for measured feature width uniformity. (DEFAULT:
selecting the same values as selected for measured
feature width uniformity.)
7.13 (measured) CD mean-to-target — the special case
of (measured) feature mean-to-target where the
selected feature is the critical dimension.
7.14 maximum feature width deviation from target —
maximum deviation of the width of a feature from its
target width in the total population of features
considered, stating the same information as in feature
width uniformity. (DEFAULT: selecting the same
information and values as used for feature width
uniformity.)
7.15 measured maximum feature width deviation from
target — maximum deviation of the measured width of
a feature from its target width in the population of
measurements, stating the same information as in
measured feature width uniformity. (DEFAULT:
selecting the same values as used for measured feature
width uniformity.)
NOTE 10: (Measured) maximum feature width deviation
from target combines (measured) feature width uniformity
and (measured) mean-to-target.
7.16 mean X-Y deviation — the difference between the
mean of considered feature widths in X and Y
directions (horizontal and vertical direction), stating the
same information as feature width uniformity.
(DEFAULT: selecting the same values as used for
feature width uniformity.)
SEMI P43-0304 © SEMI 2004 5
7.17 measured mean X-Y deviation — the difference
between the mean values of measured feature widths in
X and Y directions, stating the same information as for
measured feature width uniformity (DEFAULT:
selecting the same values as used for measured feature
width uniformity.)
7.18 X-Y deviation uniformity — the spread of the
distribution of the difference between the width of all
considered feature widths in X and Y directions
(horizontal and vertical direction), stating the same
information as feature width uniformity. (DEFAULT:
selecting the same values as used for feature width
uniformity.)
NOTE 11: For such purpose X and Y feature width
measurement locations should be as close as practically
possible.
7.19 measured X-Y deviation uniformity — the spread
of the distribution of the difference between the width
of the measured feature widths in X and Y directions
(horizontal and vertical direction), including/stating the
same information as measured feature width uniformity.
(DEFAULT: selecting the same values as used for
measured feature width uniformity.)
7.20 feature linearity error — total range of the
deviations between the mask feature width and the
respective target width on a range of feature widths (see
Figure 6a), stating as mandatory information:
• the range of feature widths used (at mask level).
(DEFAULT is the interval from the critical
dimension to 5 times this value.)
NOTE 12: The ITRS uses a wider interval.
• all types and tones of features considered, e.g., line,
contact, space, etc. (see in Section 5 for definitions
of these terms). It is a strong recommendation to
fix on 1 tone and 1 type to reach a useful number.
DEFAULT is on lines (“line linearity error”).
Contacts may be more challenging (“contact
linearity error”).
• all orientations considered, e.g., horizontal and
vertical together, horizontal only, vertical only,
including other angles, horizontal-and-vertical
separately, etc.
• the pitch of the feature (or in general: a description
of the surround(ing mask area), see further), e.g.,
equal lines and spaces, isolated line, etc., or (if
wished, but not recommended) an interval of
pitches. DEFAULT is isolated features only,
which is defined as feature intra-proximity error.
NOTE 13: If a range of pitches is included, the resulting
definition will include (inter)proximity effects. (The
ITRS mask table assumes multiple pitches.)
W
P
W
P
Figure 6
Choice of width (W) and pitch (P) in an array of
features (here shown for lines) for the determination
of a) feature linearity: varying W and P fixed;
b) feature interproximity: fixed W and varying P;
c) feature proximity: W and P BOTH varying.
7.21 measured feature linearity error — measured
value of feature linearity error, stating as mandatory
information in addition to that of measured feature
width and feature linearity error:
• the number of measurement points per feature
width (which is recommended to be more than one
measurement per feature width). If more than one
measurement per feature is taken, then the mean
value for each feature width is used.
and as optional information:
• the measured area.
• the spatial distribution of measurement locations.
7.22 feature inter-proximity error — range of the
deviations between the mask feature width of a given
size and the respective target width, on a variation of
local pattern density and configuration (i.e., of the
surround) (see Figure 6b), stating as mandatory info:
• the nominal feature width at mask level.
• all types and tones of features considered, e.g., line,
contact, space, etc. (see in Section 5 for definitions
of these terms). It is a strong recommendation to
fix on 1 tone/ 1 type to reach a useful number.
DEFAULT is on lines (line inter-proximity error).
• all orientations considered, e.g., horizontal and
vertical together, horizontal only, vertical only,
including other angles, horizontal-and-vertical
separately, etc.
• range of feature pitches. DEFAULT is equal lines-
and-spaces to isolated features. If only equal lines-
and-spaces and isolated features themselves (and
nothing in-between) are used, the term iso-dense
deviation can also be used. In more general cases
an alternative detailed description of the
SEMI P43-0304 © SEMI 2004 6
surround(ing mask area), preferably clarified with a
drawing, will replace the pitch information.
7.23 measured feature inter-proximity error —
measured value of feature inter-proximity error, stating
as mandatory information in addition to that of
measured feature width and feature inter-proximity
error:
• the number of measurement points used per pitch
or surrounding mask area (to be more than one
measurement per pitch). If more than one
measurement per pitch is taken, then the mean
value for each pitch is used.
and as optional information:
• the measured area on the mask.
• the spatial distribution of measurement locations.
7.24 feature proximity error — total range of the
deviations between the mask feature width and the
respective target width on a range of feature widths and
on a variation of local pattern density and configuration
(i.e., of the surround) (see Figure 6c), stating as
mandatory info:
• the range of feature widths used (at mask level).
(DEFAULT is the interval from the critical
dimension to 5 times this value.)
NOTE 14: The ITRS uses a wider interval.
• all types and tones of features considered, e.g., line,
contact, space, etc. (see in Section 5 for definitions
of these terms). It is a strong recommendation to
fix on 1 tone and 1 type to reach a useful number.
DEFAULT is on lines (“line proximity error”).
• all orientations considered, e.g., horizontal and
vertical together, horizontal only, vertical only,
including other angles, horizontal-and-vertical
separately, etc.
• range of feature pitches. In more general cases an
alternative detailed description of the surround(ing
mask area), preferably clarified with a drawing,
will replace the pitch information.
7.25 measured feature proximity error — measured
value of feature proximity error, stating as mandatory
information in addition to that of measured feature
width and feature proximity error:
• the number of measurement points used per pitch
or surrounding mask area (recommendation is > 1.
Then the mean value is used).
and as optional information:
• the measured area on the mask.
• the spatial distribution of measurement locations.
8 2D Mask Qualification Terminology
8.1 Introductory Remarks
8.1.1 The 2D terminology adds onto the 1D
terminology (Section 7). The 1D errors are an inherent
part of, and affect, the 2D qualification. Section 8.2
treats 2D-qualification without considering the impact
of 1D control (Section 7). Section 8.3 will suggest how
to include consequences of feature width deviation.
8.1.2 Most 2D definitions are based on a comparison of
a nominal and an actual feature/pattern. Where
relevant, appropriate alignment of nominal and actual
feature/pattern is assumed. This will be treated in detail
in Section
8.4.
8.2 True Values
NOTE 15: Reminder: The meaning of true is described in
Section 2.2. An ideal measurement then includes the idea of
perfect alignment of nominal and actual feature (see Section
8.4).
8.2.1 feature contour — shape formed by all edges of a
feature, including external and internal edges (see Note
3 in Section 5.10). If the feature considered is clipped
,
then the edge(s) clipped by the region of interest serve
as the edge(s) of the clipped feature (Figure 7).
ROI
Figure 7
Contour (for definition see Section 8.2.1, shown as a
full line,) of a clipped feature
(region of interest in light grey; the dotted line
shows the feature contour outside ROI)
8.2.2 General Approach, Based on Area
8.2.2.1 (clipped) feature area — enclosed area defined
by the edges of the (clipped) feature, i.e., area in the
(clipped) feature contour, mentioning as mandatory
information:
• description of the nominal feature including type,
dimensional information, tone, surrounding area,
and orientation relative to the coordinate system
(described in Section 6).