SIST EN 62276:2007
(Main)Single crystal wafers for surface acoustic wave (SAW) device appplications - Specifications and measuring methods
Single crystal wafers for surface acoustic wave (SAW) device appplications - Specifications and measuring methods
This International Standard applies to the manufacture of synthetic quartz, lithium niobate (LN), lithium tantalate (LT), lithium tetraborate (LBO), and lanthanum gallium silicate (LGS) single crystal wafers intended for use as substrates in the manufacture of surface acoustic wave (SAW) filters and resonators.
Einkristall-Wafer für Oberflächenwellen-(OFW-)Bauelemente - Festlegungen und Messverfahren
Tranches monocristallines pour applications utilisant des dispositifs à ondes acoustiques de surface - Spécifications et méthodes de mesure
Provides specifications for manufacturing piezoelectric single crystal wafers to be used in surface acoustic wave devices. Applies to the manufacture of synthetic quartz, lithium niobate, lithium tantalate, lithium tetraborate, and lanthanum gallium silicate single crystal wafers intended for use as substrates in the manufacture of surface acoustic wave filters and resonators.
Enokristalne rezine za površinske zvočnovalovne naprave (SAW) - Specifikacije in merilne metode (IEC 62276:2005)
General Information
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EUROPEAN STANDARD EN 62276
NORME EUROPÉENNE
EUROPÄISCHE NORM December 2005
ICS 31.140
English version
Single crystal wafers
for surface acoustic wave (SAW) device appplications -
Specifications and measuring methods
(IEC 62276:2005)
Tranches monocristallines pour Einkristall-Wafer für Oberflächenwellen-
applications utilisant des dispositifs (OFW-)Bauelemente -
à ondes acoustiques de surface - Festlegungen und Messverfahren
Spécifications et méthodes de mesure (IEC 62276:2005)
(CEI 62276:2005)
This European Standard was approved by CENELEC on 2005-11-01. CENELEC members are bound to
comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.
This European Standard exists in two official versions (English, German). A version in any other language
made by translation under the responsibility of a CENELEC member into its own language and notified to the
Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden,
Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2005 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62276:2005 E
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EN 62276:2005 - 2 -
Foreword
The text of document 49/720/FDIS, future edition 1 of IEC 62276, prepared by IEC TC 49,
Piezoelectric and dielectric devices for frequency control and selection, was submitted to the
IEC-CENELEC parallel vote and was approved by CENELEC as EN 62276 on 2005-11-01.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2006-08-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2008-11-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 62276:2005 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards
indicated:
IEC 60862-1 NOTE Harmonized as EN 60862-1:2003 (not modified).
IEC 60862-2 NOTE Harmonized as EN 60862-2:2002 (not modified).
IEC 60862-3 NOTE Harmonized as EN 60862-3:2003 (not modified).
IEC 61019-1 NOTE Harmonized as EN 61019-1:2005 (not modified).
IEC 61019-2 NOTE Harmonized as EN 61019-2:2005 (not modified).
__________
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- 3 - EN 62276:2005
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
NOTE Where an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
1) 2)
IEC 60758 - Synthetic quartz crystal - Specifications EN 60758 2005
and guide to the use
1)
IEC 60410 - Sampling plans and procedures for - -
inspection by attributes
1) 2)
ISO 4287 - Geometrical Product Specifications (GPS) EN ISO 4287 1998
- Surface texture: Profile method - Terms,
definitions and surface texture
parameters
1)
Undated reference.
2)
Valid edition at date of issue.
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INTERNATIONAL IEC
STANDARD 62276
First edition
2005-05
Single crystal wafers for surface acoustic
wave (SAW) device applications –
Specifications and measuring methods
IEC 2005 Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch Web: www.iec.ch
PRICE CODE
Commission Electrotechnique Internationale V
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue
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– 2 – 62276 IEC:2005(E)
CONTENTS
FOREWORD.4
INTRODUCTION.6
1 Scope.7
2 Normative references .7
3 Terms and definitions .7
4 Requirements .13
4.1 Material specification.13
4.2 Wafer specifications .13
5 Sampling .16
5.1 Sampling .16
5.2 Sampling frequency.17
5.3 Inspection of whole population .17
6 Test methods .17
6.1 Diameter .17
6.2 Thickness.17
6.3 Dimension of OF .17
6.4 Orientation of OF.17
6.5 TV5 .17
6.6 Warp .18
6.7 TTV.18
6.8 Front surface defects.18
6.9 Inclusions.18
6.10 Back surface roughness .18
6.11 Orientation .18
6.12 Curie temperature .18
6.13 Lattice constant.18
7 Identification, labelling, packaging, delivery condition.18
7.1 Packaging .18
7.2 Labelling and identification .18
7.3 Delivery condition.19
8 Measurement of Curie temperature .19
8.1 General .19
8.2 DTA method .19
8.3 Dielectric constant method .19
9 Measurement of lattice constant (Bond method) .20
10 Measurement of face angle by X-ray .21
10.1 Measurement principle .21
10.2 Measurement method.22
10.3 Measuring surface orientation of wafer .22
10.4 Measuring OF flat orientation .22
10.5 Typical wafer orientations and reference planes .23
11 Visual inspections .23
11.1 Front surface inspection method.23
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62276 IEC:2005(E) – 3 –
Annex A (normative) Expression using Euler angle description for piezoelectric
single crystals.24
A.1 Wafer orientation using Euler angle description .24
Annex B (informative) Manufacturing process for SAW wafers .27
B.1 Crystal growth methods .27
B.2 Standard mechanical wafer manufacturing .31
Bibliography.33
Figure 1 – Wafer sketch and measurement points for TV5 determination .9
Figure 2 – Schematic diagram of TTV .10
Figure 3 – Schematic diagram of warp .10
Figure 4 – Example of site distribution for LTV measurement. All sites have their
centres within the FQA.11
Figure 5 – LTV is a positive number and is measured at each site .11
Figure 6 – Schematic of a DTA system .19
Figure 7 – Schematic of a dielectric constant measurement system .20
Figure 8 – The Bond method.21
Figure 9 – Measurement method by X-ray.22
Figure 10 – Relationship between cut angle and lattice face .22
Figure A.1 – Definition of Euler angles to rotate coordinate system (X,Y,Z)
onto (x , x , x ).24
1 2 3
Figure A.2 – SAW wafer coordinate system .25
Figure A.3 – Relationship between the crystal axes, Euler angles,
and SAW orientation for some wafer orientations.26
Figure B.1 – Czochralski crystal growth method.27
Figure B.2 – Example of non-uniformity in crystals grown from different starting melt
compositions.29
Figure B.3 – Schematic of a vertical Bridgman furnace and example of temperature
distribution.30
Table 1 – Description of wafer orientations .12
Table 2 – Roughness, warp, TV5 and TTV specification limits .15
Table 3 – Crystal planes to determine surface and OF orientations.23
Table A.1 – Selected SAW substrate orientations and corresponding Euler angles .25
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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SINGLE CRYSTAL WAFERS FOR SURFACE ACOUSTIC
WAVE (SAW) DEVICE APPLICATIONS –
SPECIFICATIONS AND MEASURING METHODS
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62276 has been prepared by IEC technical committee 49:
Piezoelectric and dielectric devices for frequency control and selection.
This standard cancels and replaces IEC/PAS 62276 published in 2001. This first edition
constitutes a technical revision.
The text of this standard is based on the following documents:
FDIS Report on voting
49/720/FDIS 49/724/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
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62276 IEC:2005(E) – 5 –
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
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– 6 – 62276 IEC:2005(E)
INTRODUCTION
A variety of piezoelectric materials are used for surface acoustic wave (SAW) filter and
resonator applications. Prior to the 1996 Rotterdam IEC TC 49 meeting, wafer specifications
were typically negotiated between users and suppliers. During the meeting a proposal was
announced to address wafer standardization. This document has been prepared in order to
provide industry standard technical specifications for manufacturing piezoelectric single
crystal wafers to be used in surface acoustic wave devices.
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62276 IEC:2005(E) – 7 –
SINGLE CRYSTAL WAFERS FOR SURFACE ACOUSTIC
WAVE (SAW) DEVICE APPLICATIONS –
SPECIFICATIONS AND MEASURING METHODS
1 Scope
This International Standard applies to the manufacture of synthetic quartz, lithium niobate
(LN), lithium tantalate (LT), lithium tetraborate (LBO), and lanthanum gallium silicate (LGS)
single crystal wafers intended for use as substrates in the manufacture of surface acoustic
wave (SAW) filters and resonators.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60758, Synthetic quartz crystal – Specifications and guide to the use
IEC 60410, Sampling plans and procedures inspection by attributes
ISO 4287, Geometrical Product Specifications (GPS) – Surface texture: Profile method –
Terms, definitions and surface texture parameters
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
Single crystals for SAW wafer
3.1.1
as-grown synthetic quartz crystal
right-handed or left-handed single crystal quartz is grown hydrothermally. The term
“as-grown” indicates a state prior to mechanical fabrication
NOTE See IEC 60758 for further information concerning crystalline quartz.
3.1.2
lithium niobate
LN
single crystals approximately described by chemical formula LiNbO grown by Czochralski
3,
(crystal pulling from melt) or other growing methods
3.1.3
lithium tantalate
LT
single crystals approximately described by chemical formula LiTaO grown by Czochralski
3,
(crystal pulling from melt) or other growing methods
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– 8 – 62276 IEC:2005(E)
3.1.4
lithium tetraborate
LBO
single crystals described by the chemical formula to Li B O , grown by Czochralski (crystal
2 4 7
pulling from melt), vertical Bridgman, or other growing methods
3.1.5
lanthanum gallium silicate
LGS
single crystals described by the chemical formula to La Ga SiO grown by Czochralski
3 5 14,
(crystal pulling from melt) or other growing methods
3.2
manufacturing lot
established by agreement between customer and supplier
3.3 Terms and definitions related to LN and LT crystals
3.3.1
Curie temperature
T
c
phase transition temperature between ferroelectric and paraelectric phases measured by
differential thermal analysis (DTA) or dielectric measurement
3.3.2
single domain
ferroelectric crystal with uniform electrical polarization throughout (for LN and LT)
3.3.3
polarization (or poling) process
electrical process used to establish a single domain crystal
3.4 Terms and definitions related to all crystals
3.4.1
lattice constant
length of unit cell along a major crystallographic axis measured by X-ray using the Bond
method
3.4.2
congruent composition
chemical composition of a single crystal in a thermodynamic equilibrium with a molten solution
of the same composition during the growth process
3.4.3
twin
crystallographic defect occurring in a single crystal.
NOTE The twin is separated from the rest of the material by a boundary, generally aligned along a crystal plane.
The lattices on either side of the boundary are crystallographic mirror images of one another.
3.5
orientation flat
OF
flat portion of wafer perimeter indicating the crystal orientation. Generally, the orientation flat
corresponds to the SAW propagation direction. It is also referred to as the “primary flat” (see
Figure 1)
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62276 IEC:2005(E) – 9 –
3.6
secondary flat
SF
flat portion of wafer perimeter shorter than the OF. When present, the SF indicates wafer
polarity and can serve to distinguish different wafer cuts. It is also referred to as the “sub-
orientation flat” (see Figure 1)
3.7
Flatness
3.7.1
fixed quality area
FQA
central area of a wafer surface, defined by a nominal edge exclusion, X, over which the
specified values of a parameter apply
NOTE The boundary of the FQA is at all points (e.g. along wafer flats) the distance X away from the perimeter of
the wafer of nominal dimensions.
3.7.2
reference plane
depends on the flatness measurement and needs to be specified. It can be any of the
following:
a) for clamped measurements, the flat chuck surface that contacts the back surface of the
wafer;
b) three points at specified locations on the front surface within the FQA;
c) the least-squares fit to the front surface using all measured points within the FQA;
d) the least squares fit to the front surface using all measured points within one site.
3.7.3
site
square area on the front surface of the wafer with one side parallel to the OF. Flatness
parameters are assessed either globally for the FQA, or for each site individually
3.7.4
TV5 (thickness variation for five points)
TV5 is a measure of wafer thickness variation and is defined as the maximum difference
between five thickness measurements. Thickness is measured at the centre of the wafer and
at four peripheral points shown in Figure 1
1 6 mm
Index flat
2
5 4
3
Orientation flat
IEC 552/05
Figure 1 – Wafer sketch and measurement points for TV5 determination
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– 10 – 62276 IEC:2005(E)
3.7.5
total thickness variation (TTV)
measurement of TTV is performed under clamped conditions with the reference plane as
defined in 3.7.2 a). TTV is the difference between maximum thickness (A) and the minimum
thickness (B) as shown in Figure 2
A
B
Reference plane || back surface
IEC 553/05
Figure 2 – Schematic diagram of TTV
3.7.6
warp
warp describes the deformation of an unclamped wafer and is defined as the maximum
difference between a point on the front surface and a reference plane, as shown in Figure 3.
The reference plane is defined by 3-points as described in 3.7.2 b). Warp is a bulk property of
a wafer and not of the exposed surface alone
Warp = |A| + |B|
3 point
reference plane B
A
Reference
point
IEC 554/05
Figure 3 – Schematic diagram of warp
3.7.7
sori
describes the deformation of an unclamped wafer and is defined as the maximum difference
between a point on the front surface and a reference plane. In contrast to warp, in this case
the reference plane is defined by a least-squares fit to the front surface (3.7.2 c))
3.7.8
local thickness variation (LTV)
determined by a measurement of a matrix of sites with defined edge dimensions (e.g. 5 mm ×
5 mm). Measurement is performed on a clamped wafer with the reference plane as defined in
3.7.2 a). A site map example is shown in Figure 4. The value is always a positive number and
is defined for each site as the difference between the highest and lowest points within each
site, as shown in Figure 5. For a wafer to meet an LTV specification, all sites must have LTV
values less than the specified value
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62276 IEC:2005(E) – 11 –
1 2 3 ….
…. n ….
IEC 555/05
Figure 4 – Example of site distribution for LTV measurement.
All sites have their centres within the FQA
LTV
Back surface
Site 1 Site 2 Site 3 . Site n .
IEC 556/05
Figure 5 – LTV is a positive number and is measured at each site
3.7.9
percent local thickness variation
PLTV
the percentage of sites that fall within the specified values for LTV. As with the LTV
measurement, this is a clamped measurement
3.7.10
focal plane deviation
FPD
measured relative to the 3-point reference plane as defined in 3.7.2 b). The value indicates
the maximum distance between a point on the wafer surface (within the FQA) and the focal
plane. If that point is above the reference, the FPD is positive. If that point is below the
reference plane, the FPD is negative
3.8
back surface roughness
definitions of R are given in ISO 4287
a
3.9
surface orientation
crystallographic orientation of the axis perpendicular to the surface of wafer
3.10
description of orientation and SAW propagation
indicating the surface orientation and the SAW propagation direction, separated by the
symbol “-“. Specification of a 0º orientation is normally omitted. Typical examples for these
expressions are shown in Table 1.
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– 12 – 62276 IEC:2005(E)
Table 1 – Description of wafer orientations
Material LN LT Quartz LBO LGS
crystal
o o o
Expression 128 Y-X X-112 Y ST-X 45 X-Z yxlt/48,5º/26,6º
o
Y-Z 36 Y-X
o
64 Y-X
3.11
ST-cut
although the original definition is 42,75º rotated Y-cut and X-propagation, the actual cut angle
can range from 20º to 42,75º in order to achieve a zero temperature coefficient
3.12
tolerance of surface orientation
acceptable difference between specified surface orientation and measured orientation,
measured by X-ray diffraction
3.13
bevel
slope or rounding of the wafer perimeter. This is also referred to as “edge profile”. The
process of creating a bevel is called “bevelling” or “edge rounding”. The profile and its
tolerances should be specified by the supplier
3.14
diameter of wafer
diameter of circular portion of wafer excluding the OF and SF regions
3.15
wafer thickness
thickness measured at the centre of the wafer
3.16 Definitions of appearance defects
3.16.1
contamination
the first is defined as area and the second as particulate. The first is caused by surface
contaminants that cannot be removed by cleaning or are stained after cleaning. Those may be
foreign matter on the surface of, for example a localized area that is smudged, stained,
discoloured, mottled, etc., or large areas exhibiting a hazy or cloudy appearance resulting
...
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