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STANDARD
SIST EN 50513:2009
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.
SIST EN 50513:2009
EN 50513:2009 – 2 – Foreword This European Standard was prepared by the Technical Committee CENELEC TC 82, Solar photovoltaic energy systems. The text of the draft was submitted to the Unique Acceptance Procedure and was approved by CENELEC as EN 50513 on 2008-12-01. 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)
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
EN 50513:2009 – 4 – 11.6 Measuring plan . 18 11.7 Test report . 20 12 Corrosion rate
.............................................................................................................................. 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
SIST EN 50513:2009
– 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
SIST EN 50513:2009
EN 50513:2009 – 6 – 1 Scope This document describes data sheet and product information for crystalline silicon (Si) – solar wafers and measurement methods for wafer properties. The document intends to provide the minimum information required for an optimal use of crystalline silicon wafers in solar cell manufacturing. Clauses 5 to 7 describe the data sheet information with technical specifications of the silicon solar wafer with all essential characteristics. The product information concerns packaging, labelling and storage, and implies the commitment to inform about major changes of the product and in the manufacturing process. This data is needed for the processing of silicon solar wafers to solar cells. Clauses 8 to 16 describe measurement methods for the characteristic properties specified in the data sheet. 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. EN 50461, Solar cells – Datasheet information and product data for crystalline silicon solar cells EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025) DIN 5043-2, Radioactive luminescent pigments – Method of measurement and designation DIN 50431, Testing of semiconductor materials – Measurement of the resistivity of silicon or germanium single crystals by means of the four probe/direct current method with collinear array DIN 50432, Testing semi-conducting inorganic materials – Determining conduction type for silicon or germanium using a standard test or thermosonde probe (withdrawn) DIN 50434, Testing of materials for semiconductor technology – Detection of crystal defects in mono-crystalline silicon using etching techniques on [111] and [100] surfaces (ASTM F 47) DIN 50438-1, Testing of materials for semiconductor technology – Determination of impurity content in silicon by infrared absorption – Part 1: Oxygen DIN 50438-2, Testing of materials for semiconductor technology – Determination of impurity content in silicon by infrared absorption – Part 2: Carbon DIN 50441-1, Testing of materials for semiconductor technology – Determination of the geometric dimensions of semiconductor wafers – Part 1: Thickness and thickness variation DIN 50441-5, Testing of materials for semiconductor technology – Determination of the geometric dimensions of semiconductor wafers – Part 5: Terms of shape and flatness deviation DIN 4760, Form deviations – Concepts – Classification system DIN 4768, Identification of roughness characteristics Ra, Rz, Rmax with electrical testing machines – terms, conditions of measurement DIN 879-1, Verification of geometrical parameters – Dial indicator for linear measurement –
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
EN 50513:2009 – 8 –
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
SIST EN 50513:2009
– 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
EN 50513:2009 – 10 – 8 Wafer thickness 8.1 Scope This procedure describes the measurement to determine the thickness of crystalline silicon wafers by using non-contact or contact thickness measuring equipment. 8.2 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 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. 8.3 Definitions 8.3.1 Thickness The locally variable distance between the actual surface of the front and back sides of the wafer whereby the actual surface is the surface identified with measuring technology in accordance to DIN 4760. NOTE The centre thickness (thickness d5 in the middle of the wafer at measuring point 5 according to Figure 1) is often described simply as thickness. 8.3.2 Average thickness dm The average value of the 5 measuring values d1, d5, d8, d11 and d15 at the measuring points 1, 5, 8, 11 and 15 according to Figure 1: dddddd++++=12345m5 (1) The average thickness can also be calculated from weighing the wafer, taking into account the wafer area and density of silicon. 8.3.3 Centre thickness The thickness d8 at the centre of the wafer at measuring point 8 according to Figure 1: d = d8
(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 standa
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