Background Statement for SEMI Draft Document 5927 Revision of SEMI PV , SPECIFICATION FOR SILICON WAFERS FOR USE IN PHOTOVOLTAIC SOLAR CELLS

Transcription

1 Background Statement for SEMI Draft Document 5927 Revision of SEMI PV , SPECIFICATION FOR SILICON WAFERS FOR USE IN PHOTOVOLTAIC SOLAR CELLS Notice: This background statement is not part of the balloted item. It is provided solely to assist the recipient in reaching an informed decision based on the rationale of the activity that preceded the creation of this Document. Notice: Recipients of this Document are invited to submit, with their comments, notification of any relevant patented technology or copyrighted items of which they are aware and to provide supporting documentation. In this context, patented technology is defined as technology for which a patent has issued or has been applied for. In the latter case, only publicly available information on the contents of the patent application is to be provided. Background Statement A Quasi-monocrystalline silicon wafer, also called casting mono silicon wafer or mono-like silicon wafer, etc. is a type of wafer produced from crystals that are formed with a casting method (also called directional solidification method) with the use of silicon mono-crystalline seeds. This type of wafer contains large size grains (larger than hundreds of millimeters) with the same crystallographic orientation as the seed crystals. The wafer usually contains multiple grains, but would be better processed like a mono-crystal wafer in the cell line to achieve lower light reflection on the surface. Therefore, it is necessary to distinguish such wafers from multi-crystalline silicon wafers for the industry to better accept such higher performance wafer product. The existing SEMI PV specifies the typical mono- and multi- crystalline silicon wafers, which would literally categorize the quasi-monocrystalline into multi-crystalline silicon without considering the dominating large size grain which better suited for a cell process for a mono-crystal wafer. In fact, the PV Silicon Wafer Task Force of China PV standard committee has submitted 5382B Specification for Quasi-monocrystalline Silicon Wafers Used in Photovoltaic Solar Cells and then, subsequently, 5724 Guide for Specifying Quasi-monocrystalline Silicon Wafers Used in Photovoltaic Solar Cells to define and characterize the quasi-monocrystalline silicon wafer. These efforts have failed due to nonconformity with SEMI PV Thus, in order to keep the body of standards cohesive, we propose a modification to SEMI PV to include the concept of quasi-monocrystalline silicon wafers with the introduction of the area percentage of the largest grain. Review and adjudication Information Task Force Review Committee Adjudication Group: PV Silicon Wafer TF PV China TC Chapter Date: TBD 2016/03/15 Time &Time Zone: TBD 09:00~18:00 Location: TBD Kerry Hotel, Pudong City, State/Country: TBD Shanghai, China Leader(s): Yuepeng Wan(LDK Solar) Guangchun Zhang(CanadianSolar) Jun Liu(CESI) Standards Staff: Kris Shen(SEMI China) kshen@semi.org Kris Shen(SEMI China) kshen@semi.org If you have questions, please contact to PV Silicon Wafer Task Force; Linyan Liu (LDK Solar) Tel: liulinyan@ldksolar.com Or contact SEMI Staff, Kris Shen at kshen@semi.org

2 SEMI Draft Document 5927 Revision of SEMI PV , SPECIFICATION FOR SILICON WAFERS FOR USE IN PHOTOVOLTAIC SOLAR CELLS This Standard was technically approved by the global Photovoltaic Technical Committee. This edition was approved for publication by the global Audits and Reviews Subcommittee on September 12, 2011.Available at and in October Purpose 1.1 This Specification covers the requirements for silicon wafers for use in photovoltaic (PV) solar cell manufacture. To permit common processing equipment to be used in multiple fabrication lines, it is essential for the wafer dimensions to be standardized. 1.2 This Specification provides standardized dimensional and certain other common characteristics of silicon wafers based on currently widely used sizes for photovoltaic applications. 1.3 This Specification also provides a tabular specification format for order entry so that relevant nonstandardized wafer characteristics and extensions of wafer sizes for research, development, and new requirements can be easily and consistently specified in commercial transactions. 2 Scope 2.1 This Specification covers ordering information and certain requirements for single crystal silicon wafer and cast silicon wafer for photovoltaic applications. 2.2 This Specification allows all kinds of growth methods that included Czochralski (CZ) method, Floating Zone (FZ) method for single crystal silicon wafer, and casting method with and without seed for cast silicon wafer. 2.3 The Specified cast silicon wafer includes cast silicon category Ⅰwafer and cast silicon categoryⅡ wafer. 2.1 the two classes of crystalline silicon materials for photovoltaic applications that are recognized: single crystal and multicrystalline. NOTE 1: In the single crystal form, one crystallographic orientation describes the whole wafer and in the multicrystalline case there is more than one crystallographic orientation present A complete purchase specification requires that various physical properties be specified along with test methods suitable for determining their magnitude. The specification format in this Standard provides a comprehensive listing of such properties and available associated test methods (see Appendix 1). 2.3 System International (SI) units are used throughout. NOTICE: SEMI Standards and Safety Guidelines do not purport to address all safety issues associated with their use. It is the responsibility of the users of the documents to establish appropriate safety and health practices, and determine the applicability of regulatory or other limitations prior to use. 3 Referenced Standards and Documents 3.1 SEMI Standards and Safety Guidelines SEMI M35 Guide for Developing Specifications for Silicon Wafer Surface Features Detected by Automated Inspection SEMI M44 Guide to Conversion Factors for Interstitial Oxygen in Silicon SEMI M53 Practice for Calibrating Scanning Surface Inspection Systems Using Depositions of Monodisperse Polystyrene Latex Sphere on Unpatterned Semiconductor Wafer Surfaces SEMI M58 Test Method for Evaluating DMA-Based Particle Deposition Systems and Processes SEMI M59 Terminology for Silicon Technology SEMI MF26 Test Methods for Determining the Orientation of a Semiconductive Single Crystal Page 1

3 SEMI MF42 Test Methods for Conductivity Type of Extrinsic Semiconducting Materials SEMI MF84 Test Method for Measuring Resistivity of Silicon Wafers with an In- Line Four-Point Probe SEMI MF391 Test Methods for Minority Carrier Diffusion Length in Extrinsic Semiconductors by Measurement of Steady-State Surface Photovoltage SEMI MF533 Test Method for Thickness and Thickness of Variation of Silicon Wafers SEMI MF657 Test Method for Measuring Warp and Total Thickness Variation on Silicon Wafers by Noncontact Scanning SEMI MF673 Test Methods for Measuring Resistivity of Semiconductor Wafers or Sheet Resistance of Semiconductor Films with a Noncontact Eddy-Current Gage SEMI MF847 Test Methods for Measuring Crystallographic Orientation of Flats on Single Crystal Silicon Wafers by X-Ray Techniques SEMI MF978 Test Method for Characterizing Semiconductor Deep Levels by Transient Capacitance Techniques SEMI MF1617 Test Method for Measuring Surface Sodium, Aluminum, Potassium, and Iron on Silicon and Epi Substrates by Secondary Ion Mass Spectrometry SEMI MF1810 Test Method for Counting Preferentially Etched or Decorated Surface Defects in Silicon Wafers SEMI MF1982 Test Methods for Analyzing Organic Contaminants on Silicon Wafer Surfaces by Thermal Desorption Gas Chromatography SEMI PV1 Test Method for Measuring Trace Elements in Silicon Feedstock for Silicon Solar Cells by High- Mass Resolution Glow Discharge Mass Spectrometry SEMI PV9 Test Method for Excess Charge Carrier Decay in PV Silicon Materials by Non-Contact Measurements of Microwave Reflectance After a Short Illumination Pulse SEMI PV13 Test Method for Contactless Excess-Charge-Carrier Recombination Lifetime Measurement in Silicon Wafers, Ingots, and Bricks Using an Eddy-Current Sensor SEMI PV25 Test Method for Simultaneously Measuring Oxygen, Carbon, Boron and Phosphorus in Solar Silicon Wafers and Feedstock by Secondary Ion Mass Spectrometry SEMI PV28 Test Methods for Measuring Resistivity or Sheet Resistance with a Single-Sided Noncontact Eddy- Current Gauge SEMI PV39 Test Method for In-Line Measurement of Cracks in PV Silicon Wafers by Dark Field Infrared Imaging SEMI PV40 Test Method for In-Line Measurement of Saw Marks on PV Silicon Wafers by a Light Sectioning Technique Using Multiple Line Segments SEMI PV41 Test Method for In-Line, Noncontact Measurement of Thickness and Thickness Variation of Silicon Wafers for PV Applications Using Capacitive Probes SEMI PV52 Test Method for In-Line Characterization of Photovoltaic Silicon Wafers Regarding Grain Size 3.2 ANSI Standards 1 ANSI/ASME B46.1 Surface Texture (Surface Roughness, Waviness, and Lay) ANSI/ASQC Z1.4 Sampling Procedures and Tables for Inspection by Attributes 3.3 ASTM standard 2 1 American National Standards Institute, 25 West 43 rd Street, New York, NY 10036,USA,Telephone: , Fax: ; 2 American Society for Testing and Materials: 100 Barr Harbor Drive, West Conshohocken, PA , USA. Telephone: ; Fax: ; Page 2

4 ASTM E122 Standard Practice for Choice of Sample Size to Estimate the Average for a Characteristic of a Lot or Process 3.4 EN standard 3 EN Solar Wafers Data sheet and product information for crystalline wafers for solar cell manufacturing 3.5 ISO standard 4 ISO Surface Chemical Analysis Determination of Surface Elemental Contamination on Silicon Wafers by Total Reflection X-ray Fluorescence Spectroscopy (TXRF) 3.6 JEITA Standard 5 JEITA EM-3501 (18) Standard Methods for Determining the Orientation of a Semiconductive Silicon Single Crystal 3.7 JIS Standards 6 JIS H 0609 Test Methods of Crystalline Defects in Silicon by Preferential Etch Techniques JIS H 0611 Methods of Measurement of Thickness, Thickness Variation and Bow of Silicon Wafer JIS H 0614 Visual Inspection for Silicon Wafers with Specular Surfaces NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions. 4 Terminology 4.1 Terms and acronyms relating to silicon and other semiconductor technology are defined in SEMI M Other Acronyms Used in This Standard μ-pcd microwave photoconductance decay GDMS glow discharge mass spectrometry LATF local thickness fluctuations PV photovoltaic QSSPC quasi steady state photoconductance 4.3 Other Terms Used in This Standard brick one or more squared, cropped, and ground sections from an ingot ingot a cylindrical or rectangular solid of silicon resulting from a crystallization process, generally of slightly irregular dimensions monocrystalline (synonym: single crystal) a body of crystalline material that contains no large-angle boundaries or twin boundaries multicrystalline a body of crystalline material that contains large-angle boundaries or twin boundaries. Most crystals of this body have dimensions in the millimeter up to centimeter range cast silicon crystalline silicon produced by a casting method. 3 European Committee For Standardization, Avenue Marnix 17, B-1000 Brussels, Telephone: , Fax: , 4 International Organization for Standardization, ISO Central Secretariat,1,rue de Varembé, Case postale 56, CH-1211 Geneva 20, Switzerland Telephone: ; Fax: ; 5 Japanese Electronics and Information Technology Industries Association, Ote Center Building, 1-1-3, Otemachi, Chiyoda-ku, Tokyo , Japan; 6 Japanese Standards Association, Akasaka,Minato-ku,Tokyo ,Japan. Telephone: ; Fax: ; Page 3

5 Note: Wafers cut from cast silicon ingots are typically multicrystalline with grain sizes up to several centimeters, but, depending on the specific casting method used, single crystalline or nearly single crystalline wafers, sometimes called quasi-monocrystalline wafers, may also be obtained percentage of the largest single grain the area ratio of the largest grain with the same defined crystallographic orientation to the area of the cast silicon wafer, expressed in percent. 5 Ordering Information 5.1 Purchase orders for silicon wafers furnished to this specification shall include the following items. These items are indicated in the Specification Format for Order Entry, Parts 1 and 2, shown in Table A1-1 with a symbol in the left-most column Crystallization Method Crystallinity (Single crystal or cast silicon category I; II wafermulticrystalline) Shape (Square or Pseudo-square) Nominal Size Average Thickness Average Thickness Tolerance Conductivity Type Dopant Bulk Resistivity or Sheet Resistance Location of Resistivity Measurement Effective Minority Carrier Lifetime Oxygen Concentration Carbon Concentration Bulk Iron Content Dislocation Etch Pit Density (required for single crystal wafers only) Crystallographic OrientationCrystal Orientation (required for single crystal wafers only) Edge Orientation (required for single crystal wafers only), The percentage of the largest single grain (required for cast silicon wafers only) Orientation of the largest single grain (required for cast silicon wafers only) 5.2 In addition, the purchase order must indicate the test method to be used in evaluating each of those items for which alternate test procedures exist. 5.3 The following items must also be included in the purchase order: Lot acceptance procedures (see 7.2 ), Certification (if required) (see 9 ), Packing and marking (see 10 ), 5.4 Optional Criteria Any of the remainder of the items listed in Table A1-1 may be specified optionally in addition to those listed above: 5.5 In all cases, it is essential that all choices for the items included in the purchase order be made in order not to have undefined parameters that would lead to surprises between supplier and customer. 6 Requirements 6.1 General Characteristics Page 4

6 6.1.1 The crystallization method shall be as specified on the purchase order The crystallinity of the wafer shall be specified as either single crystal, or cast silicon category I; II wafer. multicrystalline The shape of the finished wafer shall be specified as square or pseudo-square. 6.2 Dimensions and Permissible Variations Wafer Thickness and Thickness Variation The center point wafer thickness shall be specified The variation of center point thickness of wafers in a lot shall be less than 5% (or other specified fraction) of the specified wafer thickness The total thickness variation within a wafer shall be specified Square Wafer Dimensions Square wafers have straight chamfers at the corners. The typical chamfer angle α, between the wafer edge and the straight chamfer is 45º, but there is no specification for this angle The allowable dimensions of square wafers are indicated in Figure 1 and Table The specified dimensions are the wafer edge lengths, A, the diagonal, G (to insure squareness of the wafer edges), and the chamfer width, H. All dimensions are given in millimeters. Other dimensions in Figure 1 can be calculated from the specified dimensions using ordinary trigonometric functions Dimension H is specified to be identical for all sizes, but by agreement between supplier and customer, one of the four corner chamfers can be of different size to indicate the orientation of the wafer TTV For all wafer sizes, the maximum TTV shall not exceed 30 μm (or other specified amount) Warp For all sizes of square wafers, the maximum warp shall not exceed 75 μm (or other specified amount). NOTE 21: The areas of square wafers are given for information in Related Information Pseudo-Square Single Crystal Wafer Dimensions Pseudo-square wafers are cut from a circular single-crystal boule and have round chamfers at the corners The allowable dimensions of pseudo-square single crystal wafers are indicated in Figure 2 and Table 2.These wafers have rounded chamfers of equal size on all four corners The specified dimensions are the wafer edge length, A, the diameter, D, and the chamfer distance, F, which is the length of a leg of a right isosceles triangle. Because F is the same for all corners, the center of the square of dimension A is the same as the center of the circle of diameter D. All dimensions are given in millimeters. The dimension, C, also shown in Figure 2 can be calculated as the length A 2F. Page 5

7 Figure 1 Table 1 Dimensions of Square Silicon Wafers for PV Solar Cell Applications Dimensions Symbol in Figure 1 #1 A (mm) G (mm) H (mm) Dimension Name Wafer Edge Length Diagonal Chamfer Length Nominal Size (mm) Max Min Max Min Max Min Symbol in EN A,B C H Symbol in SEMI M6 A,B C D #1 The letter symbols in Figure 1 differ as indicated from those in both the previous SEMI specification for silicon wafers for solar cell application (SEMI M6, now superceded by this Standard), and EN Note that both SEMI M6 and EN used a different symbol for each of the two wafer edge lengths. The dimensions shown in Figure 1 by C, E, and α do not appear in SEMI M6. The dimension E is taken from EN 50513, but values are not specified here because they are determined from the combination of G, and H TTV For all sizes of pseudo-square wafers, the maximum TTV shall not exceed 30 μm (or other specified amount) Warp For all sizes of pseudo-square wafers, the maximum warp shall not exceed 75 μm (or other specified amount). NOTE 32: The areas of pseudo-square wafers are given for information in Related Information Materials and Manufacture Page 6

8 6.3.1 The material shall consist of wafers conforming to the crystallinity class specified in the purchase order or contract. 6.4 Electrical Parameters The material shall conform to the details specified in the purchase order or contract, as follows: Conductivity type and dopant, Resistivity, Diffusion length or effective minority carrier lifetime. 6.5 Chemical Characteristics The material shall conform to the interstitial or total oxygen content, the substitutional or total carbon content, and bulk iron content as specified in the purchase order or contract In addition, the content of one or more individual metals and/or total metal content may optionally be required. In each case, the metal(s) to be determined shall be identified. 6.6 Crystal Characteristics Single crystal wafers shall conform to the maximum dislocation etch pit density and crystal and edge orientation as specified in the purchase order or contract The percentage of the largest single grain Cast silicon wafers shall be categorized by the percentage of the largest single grain as defined in Table 1. Categories I and II differ in the percentage of the largest single grain. Table 1 The Percentage of the Largest Single Grain of Cast Silicon Wafer Item #1 Cast silicon category I Cast silicon category II The percentage of the largest single grain 85% <85% #1 For cast silicon category I wafers which can be treated by anisotropic texturing (e.g., alkaline solution) to gain the well textured surface of low reflectance, instead of isotropic texturing for the traditional cast silicon category II. 6.7 Wafer Defect Limits Wafers shall conform to the defect limits as specified in the purchase order or contract. 2 Page 7

9 Figure 2 Dimensions of Pseudo-Square Single Crystal Silicon Wafers for PV Solar Cell Applications Table 2 Dimensions of Pseudo-Square Silicon Wafers for PV Solar Cell Applications Symbol in Figure 2 #1 A Dimensions(mm) D Dimension Name Wafer Edge Length Diameter Nominal Size (mm) Maximum Minimum Maximum Minimum Symbol in EN A E Symbol in SEMI M6 A B #1 The letter symbols in Figure 2 differ as indicated from those in both the previous SEMI specification for silicon wafers for solar cell application (SEMI M6, now superceded by this Standard), and EN Note that the dimensions C and F,, which are shown in Figure 2, are not listed in the dimension table because these two dimensions can be simply calculated from the edge length and diameter. 7 Sampling 7.1 Unless otherwise specified, ASTM E122 shall be used When so specified, the appropriate sample sizes shall be selected from each lot in accordance with ANSI/ASQC Z1.4. Each quality characteristic shall be assigned an acceptable quality level (AQL) and lot tolerance percent defective (LTPD) value in accordance with the ANSI/ASQC Z1.4 definitions for critical, major, and minor Page 8

10 classifications. If desired and so specified in the contract or order, each of these classifications may alternatively be assigned cumulative AQL and LTPD values. Inspection levels shall be agreed upon between the supplier and the customer. 7.2 For the purposes of this specification, a lot is either (a) all of the wafers of nominally identical size and characteristics contained in a single shipment, or (b) subdivisions of large shipments consisting of wafers as listed above that have been identified by the supplier as constituting a lot. 8 Test Methods NOTE 43: Silicon wafers are extremely fragile. While the mechanical dimensions of a wafer can be measured by use of tools such as micrometer calipers and other conventional techniques, the wafer may be damaged physically in ways that are not immediately evident. Special care must therefore be used in the selection and execution of measurement methods. 8.1 Dimensional Characteristics Length, Width, or Diameter Determine the edge length of rectangular and pseudo-square wafers by a method agreed upon between the supplier and the purchaser Center Point Thickness and Total Thickness Variation (TTV) Make these measurements with contact or non-contact equipment as agreed by supplier and purchaser. It should be noted that measurements with contact equipment are not likely to give the same result as those with non-contact equipment because of the effects of surface roughness of the test specimen Determine the center point thickness by the test methods SEMI MF533, SEMI PV41 or JIS H 0611 or by using point 8 of the 15-point pattern given in EN 50514, as indicated on the purchase order or contract. The full 15- point pattern is reproduced in Figure Determine TTV by the test methods SEMI MF533 MF533, SEMI PV41 or JIS H 0611, by using points 1, 5, 8, 11, and 15 of the 15-point pattern, by using all points in the 15 point pattern, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract. Page 9

11 NOTE: In accordance with EN 50513, the wire sawing direction goes from left to right in this figure. Figure 3 Fifteen-point Plan for Measuring Thickness of Square and Pseudo-square Silicon Wafers Warp Determine the warp by the test methods SEMI MF657 or SEMI MF1390, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract Waviness Determine the height and spatial wavelength of the waviness by ANSI/ASME B46.1 or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract. 8.2 Electrical Characteristics Conductivity Type Determine whether the wafers are p- or n-type by the test methods SEMI MF42 or JIS J 0607, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract Resistivity Determine the resistivity at the center of the wafer by the eddy current method using SEMI MF673 or SEMI PV28,, as indicated on the purchase order or contract. If the wafers are single crystal or have few grain boundaries, the four-probe method may also be used in accordance with SEMI MF84 if agreed to by the supplier and purchaser Effective Minority Carrier Lifetime Determine the effective minority carrier lifetime by the μ-pcd (SEMI PV9) or QSSPC method (SEMI PV13) or by another method as agreed to by the supplier and purchaser. 8.3 Chemical Characteristics Oxygen If interstitial oxygen content is specified, determine the oxygen content by FTIR, using the IOC- 88 conversion factor as listed in SEMI M44 unless a different factor is indicated on the purchase order or contract. If total oxygen content is specified, determine it by SIMS 7 (SEMI PV25) or another means using a method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract Carbon If the substitutional carbon content is specified, determine it by FTIR. If total carbon content is specified, determine it by SIMS 7 (SEMI PV25) or another means using a method agreed to by the supplier and purchaser as indicated on the purchase order or contract Bulk Iron Content Estimate the bulk iron content by using the DLTS (SEMI MF978) or SPV (SEMI MF391) method, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract. 7 Hockett, R. S., Solar Grade Si Impurity Evaluation Using GDMS and SIMS, 3rd International Workshop on Crystalline Silicon Solar Cells, SINTEF/NTNU, Trondheeim, Norway, 3-5 June Page 10

12 8.3.4 Other Metal Content Determine the content of other specified metal(s) by GDMS (SEMI PV1), or by SIMS 7 (SEMI PV25) or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract. 8.4 Crystal Characteristics of Single Crystalline Silicon Wafers Dislocation Etch Pit Density For single crystal silicon wafers, Determine determine the etch pit density on the surface of the wafer by SEMI MF1809 or JIS H 0609, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract Surface Orientation For single crystal silicon wafers, Determine determine in accordance with SEMI MF26, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract Edge Orientation For single crystal silicon wafers, Determine determine by the flat orientation method of SEMI MF847, or by another method agreed to by the supplier and the purchaser, if this measurement is required on the purchase order or contract The percentage of the largest single grain For cast silicon wafers, determine the percentage of the largest single grain with SEMI PV52 or by another method agreed to by the supplier and the purchaser as indicated on the purchase order or contract Orientation of the largest single grain For cast silicon wafers, determine in accordance with SEMI MF26, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract. 8.5 Surface and Edge Inspection Characteristics Area Contamination Determine by visual inspection in accordance with SEMI MF523 or JIS H 0614 or by SSIS, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract Non-visible Contamination Determine by corrosion rate measurement in accordance with 12 of EN 50513, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract Cracks Determine by visual inspection in accordance with SEMI MF523, SEMI PV39 or JIS H 0614 or by SSIS, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract Edge Breakage Determine non V-type indents at the edge by visual inspection in accordance with SEMI MF523 or JIS H 0614 or by SSIS, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract Edge Chips Determine by corrosion rate measurement in accordance with 12 of EN 50513, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract Edge Crown Determine the maximum difference between the surface elevation at 3.2 mm from the edge of the wafer and the elevation at the wafer edge in accordance with DIN 50446, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract Edge Deviation Determine the minimum spatial wavelength and the maximum deviation from a curve fitted to the edge of the wafer by a method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract Inclusions Determine the dimensions and number of visible inclusions in the silicon matrix that affect the electrical, optical, or chemical properties of the wafer by visual inspection in accordance with SEMI MF523 or JIS H 0614, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract Pits Determine the depth, width, and number of pits on the wafers surface visually by using SEMI MF523 or JIS H 0614 or by SSIS, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract. Page 11

13 Surface Roughness Determine the surface roughness by a BRDF method or by AFM or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract Groove-type Saw Marks Determine the depth and number of grooves in accordance with DIN 4774 or ANSI/ASME B46.1, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract Step-type Saw Marks Determine the depth and number of steps in accordance with DIN 4774 or ANSI/ASME B46.1, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract Surface Chips Determine by visual inspection in accordance with SEMI MF523 or JIS H 0614 or by SSIS, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract V-chips Determine by visual inspection in accordance with SEMI MF523 or JIS H 0614 or by SSIS, or by another method agreed to by the supplier and the purchaser, as indicated on the purchase order or contract Surface Metal Contamination Determine the concentration of specified metal contaminants by ICP/MS. AAS, SIMS (SEMI PV25) in accordance with SEMI MF1617, TXRF in accordance with ISO 14706, or by another method agreed to by the supplier and the purchaser as indicated on the purchase order or contract Surface Organics Determine the density of surface organics in accordance with SEMI MF1982 or by another method agreed to by the supplier and the purchaser as indicated on the purchase order or contract. 9 Certification 9.1 Upon request of the purchaser in the contract or order, a manufacturer s or supplier s certification that the material was manufactured and tested in accordance with this Specification, together with a report of the test results, shall be furnished at the time of shipment. 9.2 In the interest of controlling inspection costs, the supplier and the purchaser may agree that the material shall be certified as capable of meeting certain requirements. In this context, capable of meeting shall signify that the supplier is not required to perform the appropriate tests in 8. However, if the purchaser performs the test and the material fails to meet the requirement, the material may be subject to rejection. 10 Packing and Package Labeling 10.1 Special packing requirements shall be subject to agreement between the supplier and the purchaser. Otherwise all wafers shall be handled, inspected, and packed in such a manner as to avoid chipping, scratches, and contamination, and in accordance with the best industry practices to provide ample protection against damage during shipment The wafers supplied under these specifications shall be identified by appropriately labeling the outside of each box or other container and each subdivision thereof in which it may reasonably be expected that the wafers will be stored prior to further processing. Identification shall include as a minimum the nominal diameter, conductivity type, dopant, orientation, resistivity range, and lot number. The lot number, either (1) assigned by the original manufacturer of the wafers, or (2) assigned subsequent to wafer manufacture but providing reference to the original lot number, shall provide easy access to information concerning the fabrication history of the particular wafers in that lot. Such information shall be retained on file at the manufacturer s facility for at least one year after that particular lot has been accepted by the purchaser. 11 Related Documents 11.1 The following DIN standards no longer seem to be active on the DIN Web site ( so they have been removed from 3 and listed here for historical reference. DIN 4774 Measurement of Wave Depth with Electrical Contact Stylus Instruments DIN Measurement of the Electrical Resistivity of Silicon or Germanium Single Crystals by Means of the Four-Point-Probe Direct Current method with collinear Four Probe Array Page 12

14 DIN Determination of the Conductivity Type of Silicon or Germanium by Means of Rectification Test or Hot-Probe DIN 50433/1 Determining the Orientation of Single Crystals by Means of X-Ray Diffraction DIN 50433/2 Determining the Orientation of Single Crystals by Means of Optical Reflection Figure DIN 50433/3 Determination of the Orientation of Single Crystals by Means of Laue Back Scattering DIN Determination of Crystal Defects in Monocrystalline Silicon Using Etching Techniques on {111} and {100} Surfaces DIN 50438/1 Determination of Impurity Content in Silicon by Infrared Absorption Oxygen DIN 50438/2 Determination of Impurity Content in Silicon by infrared Absorption Carbon DIN 50441/1 Determination of the Geometric Dimensions of Semiconductor Wafers; Part 1: Measurement of Thickness DIN 50443/1 Recognition of Defects and Inhomogeneities in Semiconductor Single Crystals by X-Ray Topography: Silicon DIN Contactless Determination of the Electrical Resistivity of Semiconductor Wafers with the Eddy Current Method DIN Determining Types and Densities of Defects in Silicon Epitaxial Layers Page 13

15 APPENDIX 1 SPECIFICATION FORMAT FOR ORDER ENTRY NOTICE: The material in this Appendix is an official part of SEMI PV22 and was approved by full letter ballot procedures on September 12, 2011 A1-1 Specification Format A1-1.1 The listing in the format for order entry in Table A1-1 provides a systematic basis for constructing the purchase order for any kind of crystalline silicon wafers for photovoltaic applications. Both standardized and nonstandardized properties are included in the format together with appropriate test methodology for verifying these properties. A1-1.2 Consequently, this standard can be used both for characterizing standardized material and advanced material for development and extension of present PV technologies. A1-1.3 It may or may not be that in the future additional properties could be standardized, but inclusion in this table does not mean that such properties are expected to become standards. Table A1-1 Specification Format for Order Entry Part 1 General Information ITEM INFORMATION DATE Customer Name Purchase Order Number Line Number Item Number General specification Number Revision Level Part Number/Revision Part 2 Crystalline Silicon Wafers for Photovoltaic Solar Cells ITEM SPECIFICATION MEASUREMENT METHOD 2-1 GENERAL CHARACTERISTICS # Source Materials [ ] Virgin polysilicon; [ ] Other: (specify) [ ] Not specified Crystallization Method [ ] Cz; [ ] Bridgman; [ ] Ingot Casting; [ ] Directional Solidification; [ ] Float Zone; [ ]Other: (specify) Crystallinity [ ] Single crystal; [ ] MulticrystallineCast silicon category I #2 [ ]Cast silicon category II Shape [ ] Square [ ]; Pseudo-square # DIMENSIONAL CHARACTERISTICS # Nominal Size #34 [ ] 100 mm; [ ] 125 mm; [ ] 156 mm; [ ] 210 mm; Other Size [ ] A: ± mm; [ ] G or [ ] D: ± mm Chamfer Angle [ ]45 ± º; [ ] Other: (specify) [ ] Not specified [ ] Optical microscope; [ ] Projected image; Page 14

16 2-2.3 Center Point Thickness [ ] 200μm; [ ] 180μm; [ ] 160 μm [ ] Other: (specify) [ ] Other: (specify) [ ] SEMI MF533; [ ] JIS H 0611; [ ] Point 8 of 15 point plan (Fig. 3) [ ] Other: (specify) Thickness Tolerance [ ] ±5% max; [ ] Other: (specify) [ ] SEMI MF533; [ ] JIS H 0611; [ ] SEMI PV41 [ ] Other: (specify) Total thickness Variation(TTV) Chamfer Length (for Square Wafers) Diameter (for Pseudo Square Wafers) [ ] 30μm; [ ] 50μm; [ ] Other: (specify) [ ] 2 mm max, 0.5 mm min; [ ] Other (specify) [ ] 125 ± 1 mm; [ ] 150 ± 1 mm; [ ] 205± 1 mm; [ ] 290± 1 mm; [ ] Other (specify Warp [ ] 50μm; [ ] 75μm; [ ] Other: (specify) [ ] SEMI MF533; [ ] JIS H 0611; [ ] SEMI PV41 [ ] 15 point plan (Figure 3 ); [ ] Other: (specify) [ ] As agreed between supplier and customer [ ] As agreed between supplier and customer [ ] SEMI MF657; [ ] SEMI MF1390; [ ] Other: (specify) Waviness [ ] Max. Amplitude μm [ ] ANSI/ASME B46.1 [ ] Other: (specify) 2-3 ELECTRICAL CHARACTERISTICS # Conductive type [ ] p; [ ] n; [ ] compensated [ ] SEMI MF42; [ ] JIS H 0607; [ ] Other: (specify) Dopant [ ] B; [ ] P; [ ] Ga; [ ] Other (specify) Bulk resistivity or Sheet Resistance Target [ ] ± Tolerance [ ] Ω.cm or Target [ ] ± Tolerance [ ] Ω/sq Measured at [ ] Center Point; [ ] Other: (specify) Effective minority carrier lifetime #5 2-4 CHEMICAL CHARACTERISTICS #1 [ ] SIMS; [ ] GDMS (SEMI PV1); [ ] Other: (specify) [ ] SEMI MF673 #54 ; [ ] SEMI PV28 [ ] Other: (specify) [ ] μ-pcd (SEMI PV9); [ ] QSSPC (SEMI PV13); [ ] Other: (specify) [ ] [ _]_ μs at [ ] carrier density (cm -3 ) [ ] QSSPC (SEMI PV13); [ ] Other: (specify) Oxygen Concentration Not greater than [ ] [ ] ppma; [ ] cm 3 [ ] FTIR (interstitial, SEMI MF1188);); [ ] SIMS (total, SEMI PV25); [ ] Other: (specify) Carbon Concentration Not greater than [ ] [ ] ppma; [ ] cm 3 [ ] FTIR (substitutional, SEMI MF1391); [ ] SIMS (total, SEMI PV25); [ ] Other: (specify) Bulk Iron Content [ ] Not greater than [ ] [ ] atoms/cm3 [ ] SEMI MF978 (DLTS); [ ] SEMI MF391(SPV); [ ] ICP-MS [ ] Other (specify): Page 15

17 2-4.4 Individual Metal(s) [ ] Not greater than [ ] 10 [ ] atoms/cm3 List metal(s) included: Total Metal Content [ ] Not greater than [ ] 10 [ ] atoms/cm3 List metals included: 2-5 CRYSTAL CHARACTERISTICS #6 Required only for single crystal wafers only Dislocation Etch Pit Density CrystallographicCrystal Orientation [ ] ICP-MS [ ] GDMS (SEMI PV1); [ ] SIMS; [ ] Other (specify): [ ] ICP-MS [ ] GDMS (SEMI PV1); [ ] SIMS; [ ] Other (specify): [ ] Not greater than [ ]/cm 2 [ ] SEMI MF1810; [ ] JIS H 0609; [ ] Other: (specify) [ ] (100); [ ] (111); [ ] (110); [ ] Other: (specify) ( ) [ ] SEMI MF26 (X-Ray); [ ] SEMI MF26 (Optical); [ ] JEITA EM-3501; [ ] DIN 50433/3; [ ] Other: (specify) Edge Orientation [ ] (crystal axis) [ ] ± [ ] SEMI MF847 (Flat); [ ] Other: (specify) The percentage of the largest single grain [ ] Category I, 85% [ ] Category II, <85%; [ ] Other (specify) [ ] SEMI PV52; [ ] Other: (specify) Orientation of the largest single grain Orientation tolerance of the largest single grain 2-6 SURFACE AND EDGE INSPECTION CHARACTERISTICS Contamination, Area (Visible to Naked Eye under Lighting) Contamination not Visible to Naked Eye under Lighting [ ] (100); [ ] Other: (specify) ( ) [ ] SEMI MF26; [ ] Other: (specify) [ ]± 5 degrees; [ ] Other: (specify) [ ] SEMI MF26; [ ] Other: (specify) [ ] None; [ ] Type and Max Size mm [ ] None; [ ] Type and Max Size mm Cracks [ ] None; [ ] Other Max Number ; or [ ] Max Length mm; Edge Breakage, Indents (not v-type) [ ] Max Length mm; [ ] Max Width mm; [ ] Max Number Edge Chips #78 [ ] Max Width 1 mm; [ ] Max Depth 1mm; [ ] Max Number 2 per wafer; [ ] Other Max Width mm; [ ] Other Max Depth mm; [ ] Other Max Number Edge Crown #89 surface [ ] SEMI MF523; [ ] JIS H 0614; [ ] SSIS #6 SSIS #7 ; [ ] Other (specify) [ ] Corrosion Rate 12, EN 50513; [ ] Other: (specify) [ ] SEMI MF523; [ ] JIS H 0614; [ ] SEMI PV39; [ ] SSIS #6 SSIS #7 ; [ ] Other (specify) [ ] SEMI MF523; [ ] JIS H 0614; [ ] SSIS #6 SSIS #7 ; [ ] Other (specify) [ ] SEMI MF523; [ ] JIS H 0614; [ ] SSIS #6 SSIS #7 ; [ ] Other (specify) [ ] Other (specify) Edge Deviation [ ] Max depth mm; Min Wavelength mm Inclusions [ ] Max Number ; Max Dimensions mm Pits #910 [ ] Max Depth ; [ ] Max Width ; [ ] Max Number Surface Roughness [ ] Not greater than [ ] nm, over sp [ ] Specify: [ ] SEMI MF523; [ ] JIS H 0614; [ ] Other (specify) [ ] SEMI MF523; [ ] JIS H 0614; [ ] SSIS #6 SSIS #7 ; [ ] Other (specify) [ ] BRDF; [ ] AFM; [ ] Other (specify) Page 16

18 Saw Marks, Groove [ ] ANSI/ASME B46.1 [ ] SEMI PV40; [ ] Max Number [ ] Other: (specify) Saw Marks, Step-type [ ] ANSI/ASME B46.1 [ ] SEMI PV40; [ ] Other: (specify) Surface Chips [ ] Max Length mm; [ ] Max Width mm; V-chips, Nicks, Intents (v-type) 2-7 FRONT SURFACE CHEMISTRY Surface Metal Contamination (list desired metals separately) [ ] Max Length mm; [ ] Max Width mm; [ ] Max Number [ ] Not greater than [ ] 2 [ ] SEMI MF523; [ ] JIS H 0614; [ ] SSIS #6 SSIS #7 ; [ ] Other (specify) [ ] SEMI MF523; [ ] JIS H 0614; [ ] SSIS #6 SSIS #7 ; [ ] Other (specify) [ ] Specify: Surface Organics [ ] Not greater than [ ] ng/cm 2 [ ] SEMI MF1982; [ ] Other: (specify) #2#1 Note that indicates a required item for which a value or choice must be indicated in order to minimally specify a silicon wafer for solar cell applications. #3#2 In some parts of the world, multicrystalline is considered to be synonymous with polycrystalline. #4#3 2 For illustrations of these shapes, see Figures 1 and 2. #5#4 3 Dimensions associated with each nominal size are listed in Tables 1 and 2 for rectangular and pseudo-square cells, respectively; if another size is specified, the dimensions A and D or G must be inserted with appropriate tolerances for pseudosquare and square wafers, respectively. #6#5 4 Both types of wafers can be measured with a single-sided eddy-current gauge, a document for which is under development and will be cited when it is approved. Single crystal wafers can also be measured by 4-probe contact techniques such as SEMI MF84 #5 Measurement of the excess carrier decay using μ-pcd test method results in the determination of the effective minority carrier lifetime when the density of injected carriers is very small. If the excitation level is not low, the measured decay time does not equal the effective minority carrier lifetime, in which case one could use other test methods, but it is expected to provide information that can be related to the properties of devices for which the material is subsequently used. # ~ required for single crystal silicon wafer and 2-5.4~2-5.6 required for cast silicon wafer, respectively..#7#6 In today s technology, it may be possible to inspect for some of these items using automated surface scanning inspection systems (SSIS).Such systems should be calibrated according to SEMI M53 using reference spheres deposited in accordance with SEMI M58. Some indication of the defects separable by such instruments is provided in SEMI M35; however, a standard test procedure has yet to be developed. Application of automated inspection with the use of an SSIS must be agreed upon between supplier and customer. #8#7 Also known as chipping. #9#8 Called local thickness fluctuations (LATF) in EN #10#9 Called holes in EN 50513, but holes is not preferred because of the conflict with the positive charge carriers in silicon, which are universally known as holes. Page 17

19 RELATED INFORMATION 1 SOLAR CELL AREAS NOTICE: This related information is not an official part of SEMI PV22 and was derived from the work of the global Photovoltaic Technical Committee. This Related Information was approved for publication by full letter ballot on September 12, 2011 R1-1 Calculations of the area of square and pseudo-square silicon wafers for solar cell use are listed for information only in Tables R1-1 and R1-2 of this section. These areas are the surface areas of the cell taking into account the areas lost to facets. Table R1-1 Cell Areas for Square Wafers Cell Size Maximum Area,cm 2 Target Area,cm 2 Minimum Area,cm Table R1-1 Cell Areas for Pseudo-Square Wafers Cell Size Maximum Area,cm 2 Target Area,cm 2 Minimum Area,cm NOTICE: SEMI makes no warranties or representations as to the suitability of the standard(s) set forth herein for any particular application. The determination of the suitability of the standard(s) is solely the responsibility of the user. Users are cautioned to refer to manufacturer s instructions, product labels, product data sheets, and other relevant literature respecting any materials or equipment mentioned herein. These standards are subject to change without notice. By publication of this standard, (SEMI) takes no position respecting the validity of any patent rights or copyrights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of any such patent rights or copyrights, and the risk of infringement of such rights are entirely their own responsibility. Page 18

20