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SEMI P37-1102 © SEMI 2001, 2002 1 SEMI P37-1102 SPECIFICATION FO R EXTREME UL TRAVIOLET LITHOGRAPHY MASK SUBSTRATES This specification was technically approved by the Global Mi cropatterning Com mittee and is the direct …
SEMI P36-0600 © SEMI 20005
APPENDIX 1
NOTES
NOTE: The material in this appendix is an official part of
SEMI P36 and was approved by full letter ballot procedures
on March 1, 2000 by the Japanese Regional Standards
Committee.
A1-1 Reference patterns for adjusting CD-SEM
magnification using their pitches and reference patterns
for optimizing pattern-edge determination parameters
using their widths
A1-2 The following procedures are generally applied
to critical dimension measurements using CD-SEMs: an
electron beam linearly scans across the measured
pattern, secondary and/or reflected electrons emitted
from every electron-beam incident point are collected
to form its intensity profile, pattern edges are
determined on the intensity profile using a designated
pattern-edge determination method, and the measure-
ment value of the width of the pattern is obtained from
the distance between the two pattern edges.
A1-3 Therefore, measurement errors of CD-SEM
measurements can be partitioned into two components:
one is magnification error and another is pattern-edge
determination error. Magnification error is caused by
variation of the equipment conditions such as the
sampling pitch and incident angle of electron beam.
Pattern-edge determination error is affected by the
manner of measurement such as pattern-edge
determination algorithm used and pattern-edge
determination parameters used, and the properties of the
specimen such as pattern topography (e.g., pattern-edge
slope) and pattern material.
A1-4 Magnification error, including inter-machine
magnification error, can be detected and corrected
through measuring pitches of reference patterns, and
pattern-edge determination error could be detected and
corrected through measuring widths of the reference
patterns practical reference patterns are available for
measuring their widths. However, it seems extremely
difficult to produce practical reference patterns for
measuring their widths; the source of the problem lies
in the physics of electron beam image formation and
not because the reference patterns are somehow
inadequate because of the following reasons: (a)
reference pattern can not be determined uniquely, since
intensity profiles obtained are different from each other
dependent on pattern topography and pattern materials
even if the width of every reference pattern is the same,
(b) it is technologically difficult to solve the problem of
width change due to the contamination which changes
the measurement value of pattern width dependent on
measurement time.
NOTICE: SEMI makes no warranties or
representations as to the suitability of the guideline set
forth herein for any particular application. The
determination of the suitability of the guideline 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
guidelines are subject to change without notice.
The user’s attention is called to the possibility that
compliance with this guideline may require use of
copyrighted material or of an invention covered by
patent rights. By publication of this guideline, SEMI
takes no position respecting the validity of any patent
rights or copyrights asserted in connection with any
item mentioned in this guideline. Users of this
guideline 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.
Copyright by SEMI® (Semiconductor Equipment and Materials
International), 3081 Zanker Road, San Jose, CA 95134. Reproduction o
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the contents in whole or in part is forbidden without express written
consent of SEMI.
SEMI P37-1102 © SEMI 2001, 2002 1
SEMI P37-1102
SPECIFICATION FOR EXTREME ULTRAVIOLET LITHOGRAPHY MASK
SUBSTRATES
This specification was technically approved by the Global Micropatterning Committee and is the direct
responsibility of the North American Micropatterning Committee. Current edition approved by the North
American Regional Standards Committee on August 29, 2002. Initially available at www.semi.org
September 2002; to be published November 2002. Originally published November 2001.
1 Purpose
1.1 This specification covers the general requirements
of the substrate for Extreme Ultraviolet Lithography
(EUVL) masks.
2 Scope
2.1 This standard details the physical characteristics
required for EUVL mask substrates. The specific
material is not specified to allow for innovation in
materials and substrates.
2.2 This standard does not purport to address safety
issues, if any, associated with its use. It is the
responsibility of the users of this standard to establish
appropriate safety and health practices and determine
the applicability of regulatory limitations prior to use.
3 Referenced Standards
3.1 ISO Standard
1
ISO 14644-1 — Cleanrooms and Associated Controlled
Environments Part 1: Classification of Air Cleanliness
3.2 ANSI Standard
2
ANSI/ASQC-Z1.4 — Sampling Procedures and Tables
for Inspection by Attributes.
NOTE 1: Unless otherwise indicated, all documents cited
shall be the latest published versions.
4 Terminology
4.1 None.
5 Ordering Information
5.1 Purchase orders for EUVL mask substrates
furnished to this specification shall include the
following:
1 International Organization for Standardization, ISO Central
Secretariat, 1, rue de Varembé, Case postale 56, CH-1211 Geneva 20,
Switzerland. Telephone: 41.22.749.01.11; Fax: 41.22.733.34.30
Website: www.iso.ch
2 American Society for Quality Control, 611 East Wisconsin
Avenue, Milwaukee, WI 53202, USA
5.1.1 Material coefficient of thermal expansion (see
Section 7);
5.1.2 Defect quality area dimensions and defect limits
(see Section 9); and
5.1.3 Lot acceptance criteria (see Section 10).
6 Dimensions and Permissible Variations
6.1 The square substrates shall conform to the
dimensional tolerances appropriate to the nominal edge
length and thickness as listed in Table 1. Dimensions
are illustrated in Figure 1.
6.2 Substrates shall have chamfered or rounded edges.
The edges shall conform to the dimensional tolerances
appropriate to the nominal thickness listed in Table 2.
Dimensions are illustrated in Figure 1.
6.3 Substrates shall be identified with notches at three
corners on the backside of the substrate as shown in
Figure 1. Dimensions of notches shall be as defined in
Figure 1.
6.4 Figure 2 shows three datum points on the edges of
the mask substrate. Three datum points are also shown
on the back surface of the mask substrate. These datum
points serve as reference locations for all dimensional
measurements listed in Table 1.
7 Material Specifications
7.1 Substrate materials shall be identified as near zero
thermal expansion (NZTE). Examples of NZTE
materials are titania doped silica glass or two phase
glass ceramics.
7.2 Substrate materials shall conform to thermal
expansion characteristics defined in Table 3 over the
entire range of temperature listed and at all spatial
points within the substrate.
7.2.1 The thermal expansion properties of the substrate
are defined in four classes. The particular class of
thermal expansion material used shall be agreed upon
between user and supplier. The thermal expansion
properties of the substrate are defined over the entire
temperature range shown in Table 3.
SEMI P37-1102 © SEMI 2001, 2002 2
7.2.2 Table 3 defines the permissible range of the mean
and the permissible range of the coefficient of thermal
expansion.
7.3 The substrate material shall have specific stiffness
as defined in Table 3.
7.4 Selected physical properties of NZTE materials are
provided for information only in Appendix 1.
7.5 The front, sides, and or back surfaces of the
substrate may be coated with layers that are agreed
upon between user and supplier. The substrate
including these optional additional layers must meet all
requirements outlined in this standard.
8 Flatness Specifications
8.1 The flatness requirements for the substrate are
defined in four classes. The particular class of flatness
shall be agreed upon between user and supplier.
Substrates shall be supplied with front and back sides
having flatness as listed in Table 4 over a flatness
quality area as defined in Figure 3. The flatness error
is defined as the deviation of the surface from the plane
that minimizes the maximum deviation, which is
illustrated in Figure 4.
8.2 The global flatness requirement for the front and
back sides, which includes the region excluded from the
flatness quality area (defined in Figure 3), is shown in
Table 4.
8.3 Substrates shall be supplied with wedge angle
defined in Table 4 and defined in Figure 5.
8.4 Substrates shall be supplied with local slope angle
as defined in Table 4 and defined in Figure 4.
8.5 A low order thickness variation (LOTV)
requirement is defined over a range of spatial periods
(shown in Table 4) composing the surface profile power
spectral density. This thickness variation may be
determined from the residual flatness error of the front
and back surfaces after removing the wedge angle from
the data.
8.6 The surface roughness requirements for the front
and backside are listed in Table 4, and they are defined
over a range of spatial periods.
9 Visual Criteria
9.1 A defect quality area, which may or may not
correspond with the flatness area, shall be agreed upon
between the user and supplier. Figure 6 shows the
labeling of the dimensions of the defect quality area.
9.2 Each plate shall not have more defects than listed
in Table 5 inside the defect quality area defined in
Figure 6 on the front side. Dimensions of the quality
area shall be agreed upon between user and supplier.
Each plate shall not have more defects than listed in
Table 5 outside the defect quality area defined in Figure
6 on the front side.
9.3 Each plate shall not have more defects than listed
in Table 5 on the back side within the flatness quality
area defined in Figure 3.
10 Sampling
10.1 Unless otherwise specified, appropriate sample
sizes shall be selected from each lot in accordance with
ASQC-Z1.4. Each quality characteristic shall be
assigned an acceptable quality level (AQL) in
accordance with ASQC-Z1.4 definitions for critical,
major, and minor classifications. If desired, and so
specified in the contract or order, each of these
classifications may alternatively be assigned cumulative
AQL values. Inspection levels shall be agreed upon
between user and supplier.
11 Test Methods
11.1 Thermal Expansion — to be agreed upon between
user and supplier.
11.2 Flatness and Wedge Angle — to be agreed upon
between user and supplier.
11.3 Visual — to be agreed upon between user and
supplier.
11.4 Surface Roughness — to be agreed upon between
user and supplier.
12 Certification
12.1 Upon request of the purchaser in the contract or
order, a manufacturer's or supplier's certification that
the material was manufactured and tested in accordance
with this specification, together with a report of the test
results, shall be furnished at the time of shipment.
13 Packing and Marking
13.1 Substrates shall be packed in a class 1
environment as defined by ISO 14644-1. Containers
shall be designed to protect the substrates from
contamination in handling and transit. Substrates shall
be shipped with the acceptable flatness side toward the
front of the box. This orientation shall be indicated on
each container. Packaging shall comply with the
applicable internal, national, state, and local laws and
regulations required for shipping.