SIST EN 50513:2009

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Solarscheiben - Datenblattangaben und Produktinformation für kristalline Silizium-Scheiben zur SolarzellenherstellungTranches de silicium solaires - Fiche technique et information produit sur les tranches au silicium cristallin pour la fabrication de cellules solairesSolar wafers - Data sheet and product information for crystalline silicon wafers for solar cell manufacturing27.160Solar energy engineeringICS:Ta slovenski standard je istoveten z:EN 50513:2009SIST EN 50513:2009en,fr,de01-september-2009SIST EN 50513:2009SLOVENSKI
STANDARD
EUROPEAN STANDARD EN 50513 NORME EUROPÉENNE
EUROPÄISCHE NORM March 2009
CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: avenue Marnix 17, B - 1000 Brussels
© 2009 CENELEC -
All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50513:2009 E
ICS 27.160
English version
Solar wafers -
Data sheet and product information for crystalline silicon wafers
for solar cell manufacturing
Tranches de silicium solaires -
Fiche technique et information produit
sur les tranches au silicium cristallin
pour la fabrication de cellules solaires
Solarscheiben -
Datenblattangaben und Produktinformation für kristalline Silizium-Scheiben
zur Solarzellenherstellung
This European Standard was approved by CENELEC on 2008-12-01. 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 three official versions (English, French, 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, Bulgaria, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
at national level by publication of an identical
national standard or by endorsement
(dop)
2009-12-01 – latest date by which the national standards conflicting
with the EN have to be withdrawn
(dow)
2011-12-01 __________ SIST EN 50513:2009

– 3 – EN 50513:2009 Contents 1 Scope .6 2 Normative references .6 3 Terms, definitions and acronyms .7 4 Crystallisation process .7 5 Product characteristics .7 5.1 Size .7 5.2 Electrical characteristics .8 5.3 Surface and edge characteristics .8 5.4 Chemical characteristics .9 5.5 Crystal characteristics .9 6 Packaging, marking and storage .9 6.1 Packaging .9 6.2 Marking .9 6.3 Storage .9 7 Major changes of product and processes .9 8 Wafer thickness . 10 8.1 Scope . 10 8.2 Normative references . 10 8.3 Definitions . 10 8.4 Units . 10 8.5 Measuring equipment. 11 8.6 Measurement . 11 8.7 Evaluation
........................................................................................................................... 12 8.8 Test report
........................................................................................................................... 12 8.9 Precision of the procedure
.................................................................................................. 12 9 Variations in thickness ................................................................................................................ 13 9.1 Scope ................................................................................................................................... 13 9.2 Normative references ........................................................................................................... 13 9.3 Definition .............................................................................................................................. 13 9.4 Units ..................................................................................................................................... 13 9.5 Measuring equipment........................................................................................................... 13 9.6 Measurement
...................................................................................................................... 14 9.7 Evaluation
........................................................................................................................... 15 9.8 Test report
........................................................................................................................... 14 9.9 Precision of the procedure
.................................................................................................. 15 10 Waviness and warping ................................................................................................................. 15 10.1 Scope ................................................................................................................................... 15 10.2 Normative references ........................................................................................................... 15 10.3 Definitions ............................................................................................................................ 15 10.4 Arrangements ....................................................................................................................... 16 10.5 Test report ............................................................................................................................ 16 11 Grooves and step type saw mark ............................................................................................... 16 11.1 Scope ................................................................................................................................... 16 11.2 Definitions ............................................................................................................................ 16 11.3 Units ..................................................................................................................................... 17 11.4 Arrangements ....................................................................................................................... 17 11.5 Measuring devices ............................................................................................................... 17 SIST EN 50513:2009

.............................................................................................................................. 20 12.1 Scope ................................................................................................................................... 20 12.2 Definitions ............................................................................................................................ 20 12.3 Implementation ..................................................................................................................... 20 12.4 Analysis ................................................................................................................................ 21 12.5 Test report ............................................................................................................................ 21 13 Determining carrier lifetime measured on as cut wafer ........................................................... 21 13.1 Scope ................................................................................................................................... 21 13.2 Determination of carrier lifetime ........................................................................................... 22 13.3 General measuring conditions ............................................................................................. 23 13.4 Analysis ................................................................................................................................ 23 13.5 Test report ............................................................................................................................ 24 14 Determining minority carrier bulk lifetime measured on passivated wafers (laboratory measurement) ........................................................................................................... 24 14.1 Scope ................................................................................................................................... 24 14.2 Determination of carrier lifetime ........................................................................................... 24 14.3 Analysis ................................................................................................................................ 26 14.4 Test report ............................................................................................................................ 26 15 Electrical resistivity of multi and mono crystalline semiconductor wafers ........................... 26 15.1 Scope ................................................................................................................................... 26 15.2 Normative references ........................................................................................................... 26 15.3 Definition .............................................................................................................................. 26 15.4 Units ..................................................................................................................................... 26 15.5 Measuring devices ............................................................................................................... 27 15.6 Calibration ............................................................................................................................ 27 15.7 Sample size .......................................................................................................................... 27 15.8 Measurement of silicon wafers ............................................................................................ 27 15.9 Test report ............................................................................................................................ 28 16 Method for the measurement of substitutional atomic carbon and interstitial oxygen content in silicon used as solar material ................................................................................... 28 16.1 Scope ................................................................................................................................... 28 16.2 Referenced documents (Normative references) .................................................................. 28 16.3 Definitions ............................................................................................................................ 28 16.4 Units ..................................................................................................................................... 28 16.5 Arrangements ....................................................................................................................... 28 16.6 Measurement ....................................................................................................................... 28 16.7 Test report ............................................................................................................................ 29 Annex A (informative) Geometric dimensions, surfaces and edge characteristics ...................... 30 Annex B (informative) Optional requirements ................................................................................... 33 Bibliography ......................................................................................................................................... 34
– 5 – EN 50513:2009 Figures Figure 1 – Measurement plan for full-square and pseudo-square silicon wafers . 12 Figure 2 – Sketch of waviness
............................................................................................................. 15 Figure 3 – Sketch of warping ................................................................................................................. 16 Figure 4 – Sketch of a groove on a crystalline silicon solar wafer ........................................................ 16 Figure 5 – Sketch of a step on a crystalline silicon solar wafer
............................................................ 17 Figure 6 – Measurement plan for full-square and pseudo-square silicon wafers
................................ 18 Figure 7 – Measurement plan for steps
................................................................................................ 19 Figure 8 – Measurement plan for grooves
........................................................................................... 19 Figure 9 – Measurement plan for carrier lifetime measurement ........................................................... 23 Figure A.1 – Rectangular wafer with flat chamfer ................................................................................. 30 Figure A.2 – Square wafer with round chamfer ..................................................................................... 30 Figure A.3 – Error patterns for surface and edge characteristic ........................................................... 31 Figure A.4 – Edge swelling .................................................................................................................... 32 Figure A.5 – Deviation from ideal edge ................................................................................................. 32
Table Table 1 – Surface and edge characteristics .8
Part 1: With mechanical indication DIN 4774, Measurement of wave depth with electrical contact stylus instruments SIST EN 50513:2009

– 7 – EN 50513:2009 3 Terms, definitions and acronyms For the purposes of this document, the following terms and definitions apply. 3.1
ingot the largest connected silicon piece after the crystallisation process 3.2
brick, column, block the semi-finished silicon product after squaring with area equal to the area of the later wafer 3.3
wafer the final product of silicon processing which is the input product for solar cell production 3.4
batch size the smallest unit of wafers for which traceability is guaranteed 3.5
thickness variation ∆d (Total Thickness Variation, TTV) the largest difference from several thickness measurement values 3.6
Etch Pit Density (EPD) the number of etch pits per unit area 4 Crystallisation process The crystallisation process has to be specified e.g. ingot casting, Bridgman. 5 Product characteristics 5.1 Size
See Annex A. Shape:
Rectangular, square, round, pseudo square Dimensions:
Dimensions as nominal values with tolerances, declared in mm Area:
Declaration of nominal area in mm2 Thickness:
Average thickness with tolerances in µm (according to Clause 8) TTV:
Maximum value (according to Clause 9) Information on rectangularity (where applicable):
Maximum tolerance from 90° angle in degrees NOTE 1 The actual wafer edge may be approximated by a line determined by least squares fitting. SIST EN 50513:2009

Information on the type of angle:
• Flat chamfer: Length of hypotenuses as chamfer width (H) and angle between the wafer edge and hypotenuses (.) (see Figure A.1) • Round chamfer:
Length of a leg of a right triangle (D) and diameter of the round crystal (E) (see Figure A.2) Information about waviness and warping:
(According to Clause 10) NOTE 2 All measurements are to be carried out at standard measurement temperature (25 ± 2) °C. 5.2 Electrical characteristics Information on the dopant (B, P, Ga …) and the conductivity type (p or n). Resistivity according to Clause 15 with tolerances in Ωcm. Minimum value of average effective minority carrier lifetime measured (for multi-crystalline material on the wafer, for mono-crystalline material on the face of the ingot) with µ-PCD or QSSPC according to Clause 13 or 14. 5.3 Surface and edge characteristics Information about the maximum allowable defects on the wafer, e.g. chipping on the surface or at the edge, pinholes, saw marks, cracks, edge swelling (see Figures A.3 to A.5). Table 1 – Surface and edge characteristics Term Description Specification Surface chipping Chipping on the wafer surface Maximum permissible length, width and number (and exclusion of positions if required) Cracks Technically detectable cracks
Maximum permissible length and number Holes Permeating and non-permeating holes of all sizes (e.g. by air inclusions during the drawing process) Maximum permissible length, width and number (and exclusion of positions if required) Inclusions Inclusions in the silicon matrix visible to the naked eye which affect the electrical, chemical or optical characteristics of the wafer Maximal permissible number (and dimensions if required)
Visible contaminations Contaminations visible to the naked eye
Type and maximum permissible size if any contamination is allowed Not visible contaminations For an assessment, the etching rate can be specified according to Clause 12
Type and maximal permissible size Saw mark Grooves which typically result from failures in the slicing process; measurement according to Clause 11 Maximum permissible depth and number (per area unit) Step type saw mark Steps which typically result from failures in the slicing process; measurement according to Clause 11 Maximal permissible depth and number (per area unit) Edge chips, chipping Chipping at the wafer edge which is not visible by backlight illumination (see Figure A.3) Maximum permissible length, width and number (and exclusion of positions if required) Local thickness fluctuations (LATF) A localised swelling of the wafer edge which is not detected by measurement of TTVPV in accordance with Clause 9 (see Figure A.4) Distance a and limits for parameters b and c
– 9 – EN 50513:2009 Table 1 – Surface and edge characteristics (continued) Term Description Specification V-Chips, indents (v-type), nicks V-shaped indents/chips visible in backlight (corner radius < 0,3 mm) and wafer edge (see Figure A.3 b)) Maximum permissible length, width and number
Edge breakage, indents (not including v-type) Non V-shaped indents/chips visible in backlight (corner radius < 0,3 mm) and wafer edge (see Figure A.3 c)) Maximum permissible length, width and number Edge deviation Deviation from the ideal edge approximated by a line determined by least squares fitting (see Figure A.5) Maximum deviation from the fitted line and minimal wavelength NOTE In case of alternative terms, the preferred term is marked by underlining.
5.4 Chemical characteristics Specification of oxygen and carbon content determined according to Clause 16. 5.5 Crystal characteristics NOTE The following information refers only for mono crystalline material. Etch pitch density (EPD), with units of cm-2 determined in accordance with DIN 50434 or SEMI MF1725-1103, SEMI MF1809-0704, SEMI MF1810-0304
– Information about crystal orientation – Information on the crystallographic orientation relative to the wafer edge All information shall be provided with tolerances. 6 Packaging, marking and storage 6.1 Packaging – Packaging unit – Kind of packaging 6.2 Marking The smallest packaging unit has to be labelled with the following information: – Product type – Lot number – Quantity 6.3 Storage – Data on stack ability – Conditions during storage 7 Major changes of product and processes All relevant changes of the product or the manufacturing process, which could affect the solar cell process or the solar cell product, have to be communicated. SIST EN 50513:2009

(2) 8.4 Units All measured variables specified in 8.3.1 to 8.3.3 are indicated in micrometers. SIST EN 50513:2009

– 11 – EN 50513:2009 8.5 Measuring equipment 8.5.1 Measuring devices The following are used as measuring devices: – Contact: all measuring devices with measuring sensors on both sides, e.g. dial gauges with scaled values from a maximum of 1 µm according to DIN 879-1. Under repeat conditions, the standard deviation of the measurement values must be lower than 5 µm. The contact area may not exceed 2 mm² – Non-contact: all measuring devices based on an electrical, optical or pneumatic measuring procedure with sensors on both sides. The measurement area identified by the sensors is round in shape and has a diameter is smaller or equal to 10 mm – Fine scales with an accuracy of ± 1 mg to determine wafer thickness using weighing according to 8.3.2 8.5.2 Thickness calibration standards A set of thickness calibration standards for the thickness range from 50 µm to 350 µm, in stages of 50 µm, shall be used. The calibration standards must be traceable in relation to national standards and thickness values must be given to 1,0 µm. The standards must have smooth surfaces on both sides with average surface roughness Ra < 0,2 µm, measured in accordance with DIN 4768. Standards made of semiconductor material should be polished or etched smooth. With contact-free electrical measurements, the calibration standards must be made of a material which is equal in electrical terms to the material of the measured test samples. The temperatures for calibration and measuring should not deviate from one another by more than 2 K. 8.5.3 Adjustment and calibration From the set of thickness calibration standards, the standard will be selected with the closest thickness to each of the wafers to be measured. The thickness indicator will be adjusted in accordance with the equipment manufacturer’s instructions so that the measured value of the calibration standard is consistent with the nominal value to ± 1,0 µm. Both of the calibration standards are then measured without modification of the adjustments and are up to 50 µm thicker and 50 µm thinner than the standard used for adjustments. The measurement values obtained with these standards must be consistent with the nominal values to ± 1,0 µm. Should one of these measured values deviate by more than ± 1,0 µm from the nominal value, the measuring device is unsuitable for measurements based on this standard. 8.6 Measurement
8.6.1 Measurement plan The thickness of silicon wafers with side length “a” is measured according to Figure 1 at 5 points: positions 1, 5, 8, 11 and 15. Measurement point 8 is located in the middle of the wafer and is at the intersection point of both diagonals.
Figure 1 – Measurement plan for full-square and pseudo-square silicon wafers 8.6.2 Implementation The wafer is placed into the measurement apparatus and positioned so that measuring point 1 is within ± 2 mm between the two measuring sensors of the measuring device. The measurement takes place as shown on the measuring plan (Figure 1).
8.6.3 Influence of surface roughness Contact and non-contact measuring procedures react to the characteristics of the test specimen, in particular on their surface roughness, in different ways. Whereas non-contact sensors are detecting the surface of the microscopic surface profile at an average depth, the area surrounding the microscopic surface profile is relevant for the mechanical sensors. The difference between the measurement values for mechanical and non-contact measuring devices is of the order of the average surface finish Ra. If this is not negligible, it must be agreed between the manufacturer and user as to whether measurements are carried out with the mechanical or
non-contact measuring devices. 8.7 Evaluation From the 5 measurement values d1 to d5, dm and dz are calculated using the Equations (1) and (2). As the determination of the thickness variation according to this standard is only based on 5 measurement values, irregular geometric variations in other areas of the wafer will not be identified.
8.8 Test report The test report has to be in conformance with the reporting requirements of EN ISO/IEC 17025. It should also include: – Type and name of the measuring devices used – Centre thickness, dz SIST EN 50513:2009

– 13 – EN 50513:2009 – Average thickness, dm – Deviations from the standard, if relevant Corresponding to the respective requirements, the test report should also contain the following information: 8.9 Precision of the procedure The comparative standard deviation sR for the procedure amounts to 2 µm for dz and dm. 9 Variations in thickness
9.1 Scope This procedure describes the measurement to determine the variations in thickness (TTVPV) of crystalline silicon wafers for which both non-contact and contact thickness measuring equipment is used. 9.2 Normative references This measurement is based on part of DIN 50441-1 and contains specifications from other publications in the form of dated and undated references. These normative references are cited at the relevant points in the text and the publications are: EN ISO/IEC 17025, DIN 50441-5, DIN 4760, DIN 4768 and DIN 879-1 (see also Clause 2). In the case of dated references, subsequent modifications or revisions of the publications only form part of the standards if they have been incorporated as modifications or revisions. In the case of undated references, the last edition of the publication referred to is valid. 9.3 Definition 9.3.1 Thickness variation ∆d (TTV) The greatest difference in thickness between the 15 measurement values d1 to d15 at the measuring points 1 to 15 according to Figure 1: ∆d = max (d1, d2, d3, d4, … d15) – min (d1, d2, d3, d4,… d15) (3) 9.4 Units All measured variables specified in 9.3.1 are indicated in micrometers. 9.5 Measuring equipment 9.5.1 Measuring device The following may be used as measuring devices: – Contact: all measuring devices with measuring sensors on both sides, e.g. dial gauges with scaled values from a maximum of 1 µm according to DIN 879-1. Under repeat conditions, the standard deviation of the measurement values must be lower than 5 µm. The contact area may not exceed 2 mm² – Non-contact: all measuring equipment based on an electrical, optical or pneumatic measuring procedure with sensors on both sides. The measurement area identified by the sensors is round in shape and has a diameter smaller or equal to 10 mm SIST EN 50513:2009

9.6.1 Measurement plan The thickness variations of full-square/pseudo-square wafers on side length “a” are measured according to Figure 1 at 15 points. Measurement point s 1 to 5 and 11 to 15 are located at a distance a/6 from the wafer edge and a/3 from the measuring points 6 to 10, which are situated on the symmetry line perpendicular to the wire direction. The distance of the measurement points in the 3 measurement lines from each other is a/6. 9.6.2 Implementation The wafer is placed into the measuring device and positioned so that measuring point 8 is within ± 2 mm between the two measuring sensors of the measuring device. The measurement takes place as shown on the measuring plan (Figure 1). The temporal order of measuring the measuring points is independent of their labelling and can be realized out of sequence. 9.6.3 Influence of surface roughness Contact and non-contact measuring procedures react to the characteristics of the test specimen, in particular on their surface roughness, in different ways. Whereas non-contact sensors are detecting the surface of the microscopic surface profile at an average depth, the area surrounding the micro microscopic surface profile is relevant for the mechanical sensors. The difference between the measurement values for mechanical and non-contact measuring devices is of the order of the average surface finish Ra. If this is not negligible, it must be agreed between the manufacturer and user as to whether measurements are carried out with the mechanical or non-contact measuring devices.
9.7 Evaluation From the 15 measurement values d1 to d15, ∆d is calculated using the Equation (3), according to 9.3.1. As the determination of the thickness variation according to this standard is only based on 15 measurement values, according to these standards, irregular geometric variations in other areas of the wafer will not be identified. Should any such irregularities be identified, a full surface evenness measurement should be carried out and global thickness variations (TTV, cf. DIN 50441-5) identified.
– 15 – EN 50513:2009 9.8
Test report The test report has to be in conformance with the reporting requirements of EN ISO/IEC 17025. It should also include: – Type and name of test specimen – Type and name of the measuring devices used – Thickness variations (TTVPV) ∆d – Deviations from the standard, if relevant 9.9
Precision of the procedure The comparative standard deviation sR for the procedure amounts to 4 µm for ∆d. 10 Waviness and warping 10.1 Scope The process according to these measurements serves to determine waviness and warping of crystalline silicon wafers. Measurements of waviness are made in accordance with DIN 4774. 10.2 Normative references The publications to which this measurement refers are: EN ISO/IEC 17025, DIN 4760, DIN 4768, DIN 879-1, DIN 4774 (see also Clause 2).
In the case of dated references, subsequent modifications or revisions of the publications only form part of the standards if they have been incorporated as modifications or revisions. In the case of undated references, the last edition of the publication referred to is valid. 10.3 Definitions 10.3.1 Waviness Waviness is an irregularity of shape which predominantly occurs periodically on a surface with wave lengths λ greater than 3 mm. The local maximal amplitudes a are identified over a measuring section of 10 cm (see Figure 2). Figure 2 – Sketch of waviness 10.3.2 Warping Warping z is the distance between the base and highest point a on the wafer minus the wafer thickness d, when the wafer is laid on an even surface (see Figure 3). aSIST EN 50513:2009

Figure 3 – Sketch of warping 10.4 Arrangements The limiting values for the values a and
for waviness and z for warping in 10.3 as well as the method of measuring being the aim (e.g. DIN 4774 for waviness) should be agreed between the parties.
10.5 Test report The test report has to be in conformance with the reporting requirements of EN ISO/IEC 17025. It should also include: – Type and name of the measuring devices used – Max. waviness and max. warping of every tested wafer 11 Grooves and step type saw mark 11.1 Scope This measurement serves to determine the height of steps and the depth of grooves on crystalline silicon solar wafers. These steps and grooves are caused by the wire sawing process, also called saw marks, and therefore the steps and the grooves typically appears as lines over the wafer surface. 11.2 Definitions 11.2.1 Groove type saw marks These saw marks are local depressions in the silicon wafer surface with depth t as shown in Figure 4.
Figure 4 – Sketch of a groove on a crystalline silicon solar wafer a zdSIST EN 50513:2009

– 17 – EN 50513:2009 11.2.2 Step type saw marks These saw marks are permanent changes of the surface height of a silicon solar wafer with step height h, as shown in Figure 5.
Figure 5 – Sketch of a step on a crystalline silicon solar wafer 11.3 Units The unit of the height and the width of steps as well as the unit of depth and width of grooves is µm. The unit of the window size is also µm. 11.4 Arrangements The thresholds of the maximum allowable number as well as the maximum allowable height of steps and depth of grooves should be arranged between the wafer- and the cell manufacturer.
11.5 Measuring devices For the characterization of the saw marks, a scanning device should be used. The scanning will take place across the wafer surface, perpendicular to the saw wire direction. One or more parallel scanning tracks can be used, which will give the corresponding number of surface profiles. The position of the scanning tracks is given in Figure 6. All suitable scanning methods such as optical, capacitive or mechanical methods can be used for the characterisation of grooves and steps, provided that the lateral resolution of the device is better than or equal to 10 µm and the resolution in z-direction is better than or equal to 1 µm. For Inline measurement the resolution maybe reduced to 50 µm in the lateral direction and 2 µm in the z-direction. The scanning should be performed over the complete wafer length, in order to be able to detect grooves and steps also at the ends.
Saw wire direction Saw marks Scanning lines a y y y= a/3 SIST EN 50513:2009

– 19 – EN 50513:2009 Figure 7 – Measurement plan for steps Figure 8 – Measurement plan for grooves The measurements can be arranged as follows:
1) Select the window sizes feasible for detecting the different kinds of grooves and steps. Dependent on the equipment, many types of windows can be used simultaneously for the same measurement 2) Start the scan on the edge of the wafer, and calculate span ti for window Wi as follows:
ti = max (Yi) – min (Yi) (5)
where Yi are the depth values for each sampling point within the window Wi 3) Move the window to the next position, Wi+1, corresponding to one sample position and perform the same calculation as in 2) Sampling points Xi Window size W Depth data Yi at each sampling point Surface profile Step height h Sampling points Xi Window size W Depth data Yi at each sampling point Surface profile Groove depth h SIST EN 50513:2009

11.7 Test report The test report has to be in conformance with the reporting requirements of EN ISO/IEC 17025. It should also include: – Type and denotation of the measuring device – Maximum step height and the maximum depth of the grooves for each wafer – Discrep
...