IEC 62276:2012

IEC 62276
®
Edition 2.0 2012-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside


Single crystal wafers for surface acoustic wave (SAW) device applications –
Specifications and measuring methods

Tranches monocristallines pour applications utilisant des dispositifs à ondes
acoustiques de surface (OAS) – Spécifications et méthodes de mesure

IEC 62276:2012

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IEC 62276

®

Edition 2.0 2012-10




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE
colour

inside










Single crystal wafers for surface acoustic wave (SAW) device applications –

Specifications and measuring methods




Tranches monocristallines pour applications utilisant des dispositifs à ondes

acoustiques de surface (OAS) – Spécifications et méthodes de mesure
















INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE

PRICE CODE
INTERNATIONALE

CODE PRIX X


ICS 31.140 ISBN 978-2-83220-433-7



Warning! Make sure that you obtained this publication from an authorized distributor.

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® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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– 2 – 62276 © IEC:2012
CONTENTS
FO R EW O RD . 5
INT R O D UCT IO N . 7
1 Sc op e . 8
2 Normative references . 8
3 Terms and definitions . 8
3.1 Single crystals for SAW wafer . 8
3.2 Terms and definitions related to LN and LT crystals . 9
3.3 Terms and definitions related to all crystals . 9
3.4 Flatness . 10
3.5 Definitions of appearance defects. 13
3.6 Other terms and definitions . 13
4 Requirements . 15
4.1 Material specification . 15
4.1.1 Synthetic quartz crystal . 15
4.1.2 LN . 15
4.1.3 LT. 15
4.1.4 LBO, LGS . 15
4.2 Wafer specifications . 15
4.2.1 General . 15
4.2.2 Diameters and tolerances . 15
4.2.3 Thickness and tolerance . 15
4.2.4 Orientation flat . 16
4.2.5 Secondary flat . 16
4.2.6 Back surface roughness . 16
4.2.7 Warp . 16
4.2.8 TV5 or TTV . 16
4.2.9 Front (propagation) surface finish . 17
4.2.10 Front surface defects . 17
4.2.11 Surface orientation tolerance . 18
4.2.12 Inclusions . 18
4.2.13 Etch channel density and position of seed for quartz wafer . 18
4.2.14 Bevel . 18
4.2.15 Curie temperature and tolerance . 18
4.2.16 Lattice constant . 18
4.2.17 Bulk resistivity (conductivity) for reduced LN and LT . 18
5 Sampling plan . 19
5.1 Sampling . 19
5.2 Sampling frequency . 19
5.3 Inspection of whole population . 19
6 Test methods . 19
6.1 Diameter . 19
6.2 T hic k nes s . 19
6.3 Dimension of OF . 19
6.4 Orientation of OF . 20
6.5 TV5 . 20
6.6 Warp . 20

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62276 © IEC:2012 – 3 –
6.7 TTV . 20
6.8 Front surface defects. 20
6.9 Inclusio ns . 20
6.10 Back surface roughness . 20
6.11 Orientation . 20
6.12 Curie temperature . 20
6.13 Lattice constant . 20
6.14 Bulk resistivity . 20
7 Identification, labelling, packaging, delivery condition . 21
7.1 Packaging . 21
7.2 Labelling and identification . 21
7.3 Delivery condition . 21
8 Measurement of Curie temperature . 21
8.1 General . 21
8.2 DTA method . 21
8.3 Dielectric constant method . 22
9 Measurement of lattice constant (Bond method) . 23
10 Measurement of face angle by X-ray . 24
10.1 Measurement principle . 24
10.2 Measurement method . 25
10.3 Measuring surface orientation of wafer . 25
10.4 Measuring OF flat orientation . 25
10.5 Typical wafer orientations and reference planes . 25
11 Measurement of bulk resistivity . 26
11.1 Resistance measurement of a wafer . 26
11.2 E l ec tr od e . 26
11.3 Bulk resistivity . 27
12 Visual inspections . 27
12.1 Front surface inspection method . 27
Annex A (normative) Expression using Euler angle description for piezoelectric single
crystals . 29
Annex B (informative) Manufacturing process for SAW wafers . 33
Bibliography . 40

Figure 1 – Wafer sketch and measurement points for TV5 determination . 10
Figure 2 – Schematic diagram of TTV . 11
Figure 3 – Schematic diagram of warp . 11
Figure 4 – Example of site distribution for LTV measurement . 12
Figure 5 – LTV value of each site. 12
Figure 6 – Schematic of a DTA system . 22
Figure 7 – Schematic of a dielectric constant measurement system . 22
Figure 8 – The Bond method . 24
Figure 9 – Measurement method by X-ray . 24
Figure 10 – Relationship between cut angle and lattice planes . 25
Figure 11 – Measuring circuit . 26
Figure 12 – Resistance measuring equipment . 26

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Figure 13 – Shape of electrode . 27
Figure A.1 – Definition of Euler angles to rotate coordinate system (X, Y, Z) onto
) . 30
( x , x , x
1 2 3
Figure A.2 – SAW wafer coordinate system . 30
Figure A.3 – Relationship between the crystal axes, Euler angles, and SAW orientation
for some wafer orientations . 32
Figure B.1 – Czochralski crystal growth method . 34
Figure B.2 – Example of non-uniformity in crystals grown from different starting melt
compositions . 36
Figure B.3 – Schematic of a vertical Bridgman furnace and example of temperature
d is tr i bu t io n . 37

Table 1 – Description of wafer orientations . 14
Table 2 – Roughness, warp, TV5 and TTV specification limits . 17
Table 3 – Crystal planes to determine surface and OF orientations . 25
Table 4 – Electrode size . 27
Table A.1 – Selected SAW substrate orientations and corresponding Euler angles . 31

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62276 © IEC:2012 – 5 –
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
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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, dielectric and electrostatic devices and associated materials for frequency
control, selection and detection.
This second edition cancels and replaces the first edition of IEC 62276 published in 2005.
This second edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
– terms and definitions are rearranged in accordance with the alphabetical order;
– “reduced LN” is appended to terms and definitions;
– “reduced LT” is appended to terms and definitions;
– reduction process is appended to terms and definitions.

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The text of this standard is based on the following documents:
FDIS Report on voting
49/1005/FDIS 49/1011/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.
The committee has decided that the contents of this publication will remain unchanged until
the stability 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.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.

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62276 © IEC:2012 – 7 –
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 standard 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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– 8 – 62276 © IEC:2012
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 documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60410:1973, Sampling plans and procedures for inspection by attributes
IEC 60758:2008, Synthetic quartz crystal – Specifications and guide for use
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
Note 1 to entry: The term “as-grown” indicates a state prior to mechanical fabrication.
Note 2 to entry: 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
Note 1 to entry: This note applies to the French language only.

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62276 © IEC:2012 – 9 –
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
Note 1 to entry: This note applies to the French language only.
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
Note 1 to entry: This note applies to the French language only.
3.2 Terms and definitions related to LN and LT crystals
3.2.1
Curie temperature
T
c
phase transition temperature between ferroelectric and paraelectric phases measured by
differential thermal analysis (DTA) or dielectric measurement
3.2.2
single domain
ferroelectric crystal with uniform electrical polarization throughout (for LN and LT)
3.2.3
polarization process
electrical process used to establish a single domain crystal
Note 1 to entry: The polarization process is also referred to as “poling”.
3.2.4
reduction process
REDOX reaction to increase conductivity to reduce the harmful effects of pyroelectricity
3.2.5
reduced LN
LN treated with a reduction process
Note 1 to entry: Reduced LN is sometimes referred to as “black LN”.
3.2.6
reduced LT
LT treated with a reduction process
Note 1 to entry: Reduced LT is sometimes referred to as “black LT”.
3.3 Terms and definitions related to all crystals
3.3.1
lattice constant
length of unit cell along a major crystallographic axis measured by X-ray using the Bond
method
3.3.2
congruent composition
chemical composition of a single crystal in a thermodynamic equilibrium with a molten solution
of the same composition during the growth process

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3.3.3
twin
crystallographic defect occurring in a single crystal
Note 1 to entry: 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.
3.4 Flatness
3.4.1
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 1 to entry: 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.
Note 2 to entry: This note applies to the French language only.
3.4.2
reference plane
plane depending on the flatness measurement and which 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
3.4.3
site
square area on the front surface of the wafer with one side parallel to the OF
Note 1 to entry: Flatness parameters are assessed either globally for the FQA, or for each site individually.
3.4.4
thickness variation for five points
TV5
measure of wafer thickness v
...